Robert W Lovitt
University of Wales, College of Engineering, Faculty Member
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase... more
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586 and L.delbruckii NCIMB 11778 were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred.
The growth efficiency on the medium was tested on a 2L STR reactor operated batch wise with continuous pH control. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid.
The efficiency of the optimized medium was evaluated in terms of growth rate and doubling time through the spectrophotometric measurement of cellular biomass.
Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium
The growth efficiency on the medium was tested on a 2L STR reactor operated batch wise with continuous pH control. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid.
The efficiency of the optimized medium was evaluated in terms of growth rate and doubling time through the spectrophotometric measurement of cellular biomass.
Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium
Research Interests:
Valuable nutrients can be recovered using filtration technology from complex waste effluent sources, allowing carbon based materials to be recycled and reused. Nutrients such as phosphate , ammonia and carboxylic acid can be directly... more
Valuable nutrients can be recovered using filtration technology from complex waste effluent sources, allowing carbon based materials to be recycled and reused. Nutrients such as phosphate , ammonia and carboxylic acid can be directly applied in a wide range of fields in presents day industry including their use in the fertilizers production industry, textiles, cosmetics in the food industry. To address this challenge, effluents deriving from anaerobic digestion, were utilized for the recovery of these materials using filtration technology. This neutral process will consist a valuable carbon neutral waste processing strategy that is highly beneficial for the environment while providing industry with materials and reasonable cost.
Research Interests: Engineering, Environmental Engineering, Chemical Engineering, Water, Biochemical Engineering, and 13 moreWater quality, Bioenergy, Municipal Solid Waste Management, Water Treatment, Wastewater Treatment, Waste Management, Solid Waste Management, Biofuels, Anaerobic Digestion, Anaerobic digestion of organic wastes in relation to energy, Bioprocessing, Bioproducts, and Biomass Processing
The recovery of valuable nutrients, from waste sources allows carbon based materials to be recycled and reused through the production of organic materials. For example, phosphate and ammonia, can be directly applied in a wide range of... more
The recovery of valuable nutrients, from waste sources allows carbon based materials to be recycled and reused through the production of organic materials. For example, phosphate and ammonia, can be directly applied in a wide range of fields in today’s industrial world including their use in the fertilizers production industry, textiles, cosmetics in the food industry. The aim of this research is the ability to recover these sources from waste processes, such as anaerobic digestion and promote these materials in the industry. These neutral processes will provide valuable carbon neutral processes that are highly beneficial for the environment as provide industry with materials and reasonable cost.
Keywords: waste process, nutrients, particle size, dry matter, ammonia, phosphate, environment, conductivity, salinity, sludge""
Keywords: waste process, nutrients, particle size, dry matter, ammonia, phosphate, environment, conductivity, salinity, sludge""
Research Interests:
A great number of Gram (+) and Gram negative (-) bacteria produce during their growth, substances of protein structure (either proteins or polypeptides) possessing antimicrobial activities, called bacteriocins. Although bacteriocins could... more
A great number of Gram (+) and Gram negative (-) bacteria produce during their growth, substances of protein structure (either proteins or polypeptides) possessing antimicrobial activities, called bacteriocins. Although bacteriocins could be categorized as antibiotics, they are not. The major difference between bacteriocins and antibiotics is that bacteriocins restrict their activity to strains of species related to the producing species and particularly to strains of the same species, antibiotics on the other hand have a wider activity spectrum and even if their activity is restricted this does not show any preferential effect on closely related strains. In addition, bacteriocins are ribosomally synthesized and produced during the primary phase of growth, though antibiotics are usually secondary metabolites. Among the Gram (+) bacteria, lactic acid bacteria (LAB) especially, Lactobacilli have gained particular attention nowadays, due to the production of bacteriocins. These substances can be applied in the food industry as natural preservatives. The use of LAB and of their metabolic products is generally considered as safe (GRAS, Grade One). The application of the produced antimicrobial compounds as a natural barrier against pathogens and food spoilage caused by bacterial agents has been proven to be efficient. Nisin is the only bacteriocin that has been officially employed in the food industry and its use has been approved worldwide. Bacteriocins can be applied on a purified or on a crude form or through the use of a product previously fermented with a bacteriocin producing strain as an ingredient in food processing or incorporated through a bacteriocin producing strain (starter culture).
Keywords: Lactic acid bacteria, Lactobacilli, Bacteriocins, Nisin, Plantaricins, Lantibiotics
Keywords: Lactic acid bacteria, Lactobacilli, Bacteriocins, Nisin, Plantaricins, Lantibiotics
Research Interests:
Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though, their production phase, their biochemical nature,... more
Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though, their production phase, their biochemical nature, their mode of activity even their genetic structure have been widely investigated, there are hardly any studies investigating their potency and activity in depth of time, in other words their shelf life under several physicochemical conditions that may occur during their production in large scale. As such, the effect of several factors influencing the activity and the potency of bacteriocins when produced in large scale was examined as due to bacteriocins peptide nature degradation or denaturation might occur, under extreme physicochemical conditions. During scale-up process, differences between the output data may occur, such as concerning biomass, metabolic by-products and limiting substrate concentrations. These may affect negatively the activity and the potency of the bacteriocins. For investigating these effects and minimizing them, numerous studies were conducted, which were related to the exact phase of the production of these substances, the effect of dilution and temperature changes. These studies could be used in order to minimize the scaling-up effect when decided to produce these peptides in large scale.
Research Interests: Engineering, Chemical Engineering, Bioinformatics, Microbiology, Food Science, and 14 moreFood Safety, Immunology, Molecular Biology, Biochemical Engineering, Probiotics, Dairy Science, Biotechnology, Cheese Making, Bioprocess/ Biochemical Engineering, Food Science and Technology, Genetic Engineering, Probiotics in Dairy Foods, Probiotics, Bacteriocin producing microbes and its application, and Lactic acid bacteria – Lactobacilli – Bacteriocins – Heat treatment – Potency – Activity – Nisin(Food Safety, Immunology, Molecular Biology, Biochemical Engineering, Probiotics, Dairy Science, Biotechnology, Cheese Making, Bioprocess/ Biochemical Engineering, Food Science and Technology, Genetic Engineering, Probiotics in Dairy Foods, Probiotics, Bacteriocin producing microbes and its application, and Lactic acid bacteria – Lactobacilli – Bacteriocins – Heat treatment – Potency – Activity – Nisin)
(Food Safety, Immunology, Molecular Biology, Biochemical Engineering, Probiotics, Dairy Science, Biotechnology, Cheese Making, Bioprocess/ Biochemical Engineering, Food Science and Technology, Genetic Engineering, Probiotics in Dairy Foods, Probiotics, Bacteriocin producing microbes and its application, and Lactic acid bacteria – Lactobacilli – Bacteriocins – Heat treatment – Potency – Activity – Nisin)
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase... more
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculums concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid. The efficiency of the medium combining al the optimised parameters, enhancing the productivity biomass and therefore bacteriocins production from the strains, was tested on a 2L STR reactor operated batch wise with continuous pH control. A simple liquid turbidometric method was developed to test the bacteriocin productivity of the selected bacteria. The activity and potency of the bacteriocin produced was tested against L.delbruckii subsp.lactis NCIMB 8117.
Index Terms-Doubling time, Growth rate, Lactic acid, Nisin
Index Terms-Doubling time, Growth rate, Lactic acid, Nisin
Research Interests:
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural... more
Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities was investigated through several techniques. Selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586 and L.delbruckii NCIMB 11778 were grown into batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth was developed. The efficiency of the medium was tested in a 2L STR reactor operated batch wise with continuous pH control. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactate. Efficiency of the optimized medium was evaluated in terms of growth rate and doubling time through the spectrophotometric measurement of cellular biomass. The medium strongly supports the growth of the Lactobacilli giving a growth rate between 0.22 to 0.32 h-1
Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium.
Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium.
Research Interests:
Fermentation technology has been a widely researched and exploited field of the science of biotechnology. Through out the recent years the vast majority of microbial groups have been tested for the production of beneficial compounds... more
Fermentation technology has been a widely researched and exploited field of the science of biotechnology. Through out the recent years the vast majority of microbial groups have been tested for the production of beneficial compounds especially for the replacement of products produced by petrol such as lactic acid. A bacterial group that heavily attracts attention due to its products are Lactic Acid Bacteria (LAB) and especially Lactobacilli. Lactobacilli are widely used in the food and pharmaceutical industry nowadays. These microorganisms have several distinguishing features based on their main ability to ferment carbohydrates such as the production of acids, enzymes and natural antimicrobial substances called bacteriocins. They are mainly used as natural acidifiers for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. In this article some of the most important uses of Lactobacilli in the industry will be reviewed. Emphasis will be given in the production of lactic acid, β-galactosidase and lantibiotics through the usage of modern fermentation technology.
Keywords: LAB, fermentation technology, food industry, β-galactosidase, lactic acid.
Keywords: LAB, fermentation technology, food industry, β-galactosidase, lactic acid.
Research Interests:
"Volatile fatty acids (VFA) including acetic, butyric, formic and propionic are extensively utilized in contemporary industry. Their commercial value is of high significance while their often derive from petroleum which is non-abundance... more
"Volatile fatty acids (VFA) including acetic, butyric, formic and propionic are extensively utilized in contemporary industry. Their commercial value is of high significance while their often derive from petroleum which is non-abundance source. Other methods for the production and recovery from these substances have been proposed and investigated. Waste effluent streams are potential candidates for VFA recovery, especially if for their processing filtration technology will be used. Membrane filtration is an effective and efficient choice as it is a low cost, low energy, easy integrated method tested for the separation and concentration.
"
"
Research Interests: International Development, Energy, Waste recycling, Corporate Sustainability, Waste Management, and 11 moreBiogas, Hazardous Waste, Solid Waste Management, Anaerobic Digestion, Greenhouse Effect, Institutional Sustainability, Sustainability in construction industry, Sustainable Water & Sanitation, Waste, Materials and Consumption, Social Aspects of Sustainability, and Geographic Information Systems (GIS)(Biogas, Hazardous Waste, Solid Waste Management, Anaerobic Digestion, Greenhouse Effect, Institutional Sustainability, Sustainability in construction industry, Sustainable Water & Sanitation, Waste, Materials and Consumption, Social Aspects of Sustainability, and Geographic Information Systems (GIS))
(Biogas, Hazardous Waste, Solid Waste Management, Anaerobic Digestion, Greenhouse Effect, Institutional Sustainability, Sustainability in construction industry, Sustainable Water & Sanitation, Waste, Materials and Consumption, Social Aspects of Sustainability, and Geographic Information Systems (GIS))
Current separation, isolation and purification techniques to obtain highly potent purified lactobacilli and lactococcoi bacteriocins include chemical precipitation, separation employing solvents and chromatographic techniques. These... more
Current separation, isolation and purification techniques to obtain highly potent purified
lactobacilli and lactococcoi bacteriocins include chemical precipitation, separation employing solvents
and chromatographic techniques. These methods are arduous, costly, with limited scalability, offering
low bacteriocin yields (<20%). To address these challenges, the alternatives of ultrafiltration and
nanofiltration, as separation methods were tested. Three promising bacteriocin producing strains,
Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014 and Lactococcus lactis NCIMB
8586 were selected to investigate the applicability and feasibility of the method.
To facilitate separation, the microorganisms were grown on specially developed low molecular weight
medium (LMWM) mainly containing nutritive sources up to 4 kDa molecular weight. Bacterial cells
were removed by centrifugation. The clarified broths were filtered using 4 and 1 kDa MWCO.
Bacteriocin activity was determined by an antimicrobial activity test using nisin, which has an
inhibitory effect on the growth of susceptible microorganisms. Recovery yields using filtration were
found to range between 53 to 68%, a high recovery performance.
The bacteriocin activity of crude extracts of all the three lactobacilli were between 95-105 IU ml-1.
When the substances were separated using ultrafiltration membrane (4kDa MWCO) their activity was
enhanced to 145-150 IU ml-1, achieving a total potency yield of 44% to 53%. Further enhancement of
yields up to 36% was attained employing nanofiltration (1 kDa MWCO) membranes with an activity
increased up to 200 IU ml-1.
Bacteriocin isolation from crude extracts using filtration was found to be effective, offering high
recovery yields, optimizing their activity as well as presenting a realistic option towards the
formulation of these as commercially available antibacterial agents.
lactobacilli and lactococcoi bacteriocins include chemical precipitation, separation employing solvents
and chromatographic techniques. These methods are arduous, costly, with limited scalability, offering
low bacteriocin yields (<20%). To address these challenges, the alternatives of ultrafiltration and
nanofiltration, as separation methods were tested. Three promising bacteriocin producing strains,
Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014 and Lactococcus lactis NCIMB
8586 were selected to investigate the applicability and feasibility of the method.
To facilitate separation, the microorganisms were grown on specially developed low molecular weight
medium (LMWM) mainly containing nutritive sources up to 4 kDa molecular weight. Bacterial cells
were removed by centrifugation. The clarified broths were filtered using 4 and 1 kDa MWCO.
Bacteriocin activity was determined by an antimicrobial activity test using nisin, which has an
inhibitory effect on the growth of susceptible microorganisms. Recovery yields using filtration were
found to range between 53 to 68%, a high recovery performance.
The bacteriocin activity of crude extracts of all the three lactobacilli were between 95-105 IU ml-1.
When the substances were separated using ultrafiltration membrane (4kDa MWCO) their activity was
enhanced to 145-150 IU ml-1, achieving a total potency yield of 44% to 53%. Further enhancement of
yields up to 36% was attained employing nanofiltration (1 kDa MWCO) membranes with an activity
increased up to 200 IU ml-1.
Bacteriocin isolation from crude extracts using filtration was found to be effective, offering high
recovery yields, optimizing their activity as well as presenting a realistic option towards the
formulation of these as commercially available antibacterial agents.
Research Interests: Engineering, Environmental Engineering, Chemical Engineering, Chemical Education, Bacteriology, and 38 moreBiochemical Engineering, Membranes, Water quality, Probiotics, Catalysis, Bioenergy, Process Modeling and Simulation, Water and wastewater treatment, Water Treatment, Wastewater Treatment, Nanocomposites, Bioprocess/ Biochemical Engineering, Industrial Engineering, Industrial Biotechnology, Reaction engineering, Transport phenomena, Separation Techniques, Downstream Processing, Food Microbiology, Membrane Separation Technology, Ultrafiltration, Biofuels, Nanofiltration, Probiotics, Bacteriocin producing microbes and its application, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Industrial Microbiology, Food Microbilogy,medical Bacteriology, Ultrafiltration membrane, Bioprocessing, Biofuel cells, Bioproducts, Biomass Processing, Membrane Filtration, Particle Size Studies, Virus Filtration, Membrane Science and Technology, Process Economics, Reactor Design, and Structured Catalysis(Biochemical Engineering, Membranes, Water quality, Probiotics, Catalysis, Bioenergy, Process Modeling and Simulation, Water and wastewater treatment, Water Treatment, Wastewater Treatment, Nanocomposites, Bioprocess/ Biochemical Engineering, Industrial Engineering, Industrial Biotechnology, Reaction engineering, Transport phenomena, Separation Techniques, Downstream Processing, Food Microbiology, Membrane Separation Technology, Ultrafiltration, Biofuels, Nanofiltration, Probiotics, Bacteriocin producing microbes and its application, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Industrial Microbiology, Food Microbilogy,medical Bacteriology, Ultrafiltration membrane, Bioprocessing, Biofuel cells, Bioproducts, Biomass Processing, Membrane Filtration, Particle Size Studies, Virus Filtration, Membrane Science and Technology, Process Economics, Reactor Design, and Structured Catalysis)
(Biochemical Engineering, Membranes, Water quality, Probiotics, Catalysis, Bioenergy, Process Modeling and Simulation, Water and wastewater treatment, Water Treatment, Wastewater Treatment, Nanocomposites, Bioprocess/ Biochemical Engineering, Industrial Engineering, Industrial Biotechnology, Reaction engineering, Transport phenomena, Separation Techniques, Downstream Processing, Food Microbiology, Membrane Separation Technology, Ultrafiltration, Biofuels, Nanofiltration, Probiotics, Bacteriocin producing microbes and its application, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Industrial Microbiology, Food Microbilogy,medical Bacteriology, Ultrafiltration membrane, Bioprocessing, Biofuel cells, Bioproducts, Biomass Processing, Membrane Filtration, Particle Size Studies, Virus Filtration, Membrane Science and Technology, Process Economics, Reactor Design, and Structured Catalysis)
An economic liquid growth medium was synthesised for high-rate production of cellular mass, lactic acid and bacteriocin in lactobacilli. Three lactobacilli that are applied extensively in industry—Lactobacillus casei NCIMB 11970,... more
An economic liquid growth medium was synthesised for high-rate production of cellular mass, lactic acid and bacteriocin in lactobacilli. Three lactobacilli that are applied extensively in industry—Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586—were chosen to test the medium’s efficiency. These bacteria are chemoorganotrophs requiring rich, complex media for optimum growth. Contrary to the current practice of formulating a strain-specific medium, we attempted to prepare a universal broth that would allow easy formulation and optimisation. Man de Rogosa Sharp (MRS) medium, which can support the growth of lactobacilli, was found unsuitable for use in large quantities due to its high cost of preparation and its use of beef extract and peptone from poultry as nitrogen sources, which are not environmentally friendly and have potential health risks. The developed medium supported the growth of all the three bacteria equally, offering good maximum yields and incorporating only the chemical compounds needed, resulting in an improvement in the growth rate of the bacilli of between 50 % and 241 % compared to the same strains grown on MRS. Lactic acid production was between 28.6 and 35.74 g L−1 and bacteriocin production ranged from 110 to 130 IU mL−1.
Research Interests:
The recovery of volatile fatty acids (VFA), from complex effluent streams deriving from numerous sources has been an area of research interest for more than a century. In the current era, technological and economic development is widely... more
The recovery of volatile fatty acids (VFA), from complex effluent streams deriving from numerous sources has been an area of research interest for more than a century. In the current era, technological and economic development is widely based on the limited global petroleum resources. Regardless the scarcity faced in coal based fuels, VFA are still extensively and in most cases solely, synthesised from petroleum. With the constantly rising
awareness of the environmental impact the carbon based economy has created, research has been focused in
developing alternative methods of their production. These include fermentation, anaerobic digestion and recovery
from discharged chemical and industrial plants effluents.
During these processes, the hydrolysis of target solid wastes followed by the microbial conversion of them to
biodegradable organic, content results in the production of intermediate VFA, commonly acetate and butyrate.
These, are detected at varying concentrations in the effluent streams and mixed liquors of the reactor systems. Their
concentration is depending on hydraulic, retention and organic loading rates. Several studies have shown possible environmental and commercial benefits using various techniques for their separation and recovery. Among these, extensively applied has been reactive extraction. Currently, membrane
filtration is most prominent as a source separation process in comparison to integral wastewater treatment.
VFA reclamation benefits include the formulation of a valorisized waste effluent that can be further processed for the recovery of valuable nutrients, the relief of municipal treatment plants and the recycle and re-use of favorable nutrients and chemicals."
awareness of the environmental impact the carbon based economy has created, research has been focused in
developing alternative methods of their production. These include fermentation, anaerobic digestion and recovery
from discharged chemical and industrial plants effluents.
During these processes, the hydrolysis of target solid wastes followed by the microbial conversion of them to
biodegradable organic, content results in the production of intermediate VFA, commonly acetate and butyrate.
These, are detected at varying concentrations in the effluent streams and mixed liquors of the reactor systems. Their
concentration is depending on hydraulic, retention and organic loading rates. Several studies have shown possible environmental and commercial benefits using various techniques for their separation and recovery. Among these, extensively applied has been reactive extraction. Currently, membrane
filtration is most prominent as a source separation process in comparison to integral wastewater treatment.
VFA reclamation benefits include the formulation of a valorisized waste effluent that can be further processed for the recovery of valuable nutrients, the relief of municipal treatment plants and the recycle and re-use of favorable nutrients and chemicals."
Research Interests: Engineering, Environmental Engineering, Chemical Engineering, Biochemical Engineering, Water quality, and 14 moreBioenergy, Waste recycling, Waste-to-Energy, Water Treatment, Wastewater Treatment, Waste Management, Industrial Engineering, Biofuels, Anaerobic Digestion, Waste water treatment, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Bioprocessing, Bioproducts, and Biomass Processing(Bioenergy, Waste recycling, Waste-to-Energy, Water Treatment, Wastewater Treatment, Waste Management, Industrial Engineering, Biofuels, Anaerobic Digestion, Waste water treatment, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Bioprocessing, Bioproducts, and Biomass Processing)
(Bioenergy, Waste recycling, Waste-to-Energy, Water Treatment, Wastewater Treatment, Waste Management, Industrial Engineering, Biofuels, Anaerobic Digestion, Waste water treatment, Microbiology; Fermentation Technology; Bioprocess and Biochemical Engineering, Bioprocessing, Bioproducts, and Biomass Processing)
"In the present study, a monolithic alumina coated microfiltration ceramic membrane was used for solid particulates removal and nutrients recovery from anaerobic digester complex effluent streams. The aim was to test the effect of the... more
"In the present study, a monolithic alumina coated microfiltration ceramic membrane was used for solid particulates removal and nutrients recovery from anaerobic digester complex effluent streams. The aim was to test the effect of the cake layer developed by the solids, on the surface of the membrane channels, to the filterability of these materials. The solids content ranged between 2.6 g/L to 15.1 g/L. During practical application, two processing techniques targeting the enhanced recovery of the materials of interest including ammonia, phosphate, calcium bicarbonate and volatile fatty acids, namely dewatering and diafiltration, were used. These had an immediate effect on the solids content (PDS 13μm to 3.97μm) enhancing the filterability of the effluents. Their processability was evaluated in terms of flux, cross flow velocity, membrane resistance and cake resistance. Important findings of this study is the nonalignment of the flux rates to the cake resistance, explained by the formation of a compressible, permeable cake layer that allowed the continuous operation of the system, under constant low pressure conditions (TMP 15 psi). Permeate flux remained constant to 120 L/m2 h when applying diafiltration, while when dewatering process is used the permeate flux remained constant at 115.4 L/m2 h.
Keywords: sludge; ceramic filter; cake resistance; flux; cross flow filtration"
Keywords: sludge; ceramic filter; cake resistance; flux; cross flow filtration"
Research Interests: Water and wastewater treatment, Waste recycling, Wastewater Treatment, Waste Management, Agricultural Biotechnology, and 9 moreAgricultural Water Management, Wastewater, Waste water treatment, Microfiltration, Ultrafiltration membrane, Ultrafiltration/diafiltration, Membrane Filtration, Utilization of Waste Nutrients, and Recycling of Nutrients
Lactobacilli belong to the group of Lactic Acid Bacteria (LAB), widely used in the dairy industry nowadays. These bacteria are used as a natural acidifier, for the inoculation of bulk quantities of milk and vegetables, in order to produce... more
Lactobacilli belong to the group of Lactic Acid Bacteria (LAB), widely used in the dairy industry nowadays. These bacteria are used as a natural acidifier, for the inoculation of bulk quantities of milk and vegetables, in order to produce a variety of fermented products. As such, large quantities of their biomass are necessary. In addition, during their growth, they naturally produce antimicrobial substances, called bacteriocins. Due to the constantly developing need for natural food preservatives, bacteriocin function and activity has been extensively investigated.
The possibility of producing these substances in mass quantities will be investigated through several techniques. Three carefully selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970 and L.lactis NCIMB 8586 were grown into simple batch cultures without pH control, where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for their propagation an optimised growth medium occurred. A simple, liquid turbidometric method was developed to test the bacteriocin productivity of these strains. The antimicrobial activity and potency of the bacteriocins produced, were tested against the target strain L.delbruckii subsp.lactis NCIMB 8117.
The optimised medium was then filtrated via membrane modules of 4 and 30 kDa , in an effort to simplify the medium and facilitate the extraction of the produced substance. The medium’s efficiency in supporting the growth and the bacteriocin production of the bacilli was tested and comparative studies between filtrated and unfiltrated media were done.
Keywords: LAB, Bacteriocins, Target strain, Ultrafiltration, Growth rate, Doubling time""
The possibility of producing these substances in mass quantities will be investigated through several techniques. Three carefully selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970 and L.lactis NCIMB 8586 were grown into simple batch cultures without pH control, where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for their propagation an optimised growth medium occurred. A simple, liquid turbidometric method was developed to test the bacteriocin productivity of these strains. The antimicrobial activity and potency of the bacteriocins produced, were tested against the target strain L.delbruckii subsp.lactis NCIMB 8117.
The optimised medium was then filtrated via membrane modules of 4 and 30 kDa , in an effort to simplify the medium and facilitate the extraction of the produced substance. The medium’s efficiency in supporting the growth and the bacteriocin production of the bacilli was tested and comparative studies between filtrated and unfiltrated media were done.
Keywords: LAB, Bacteriocins, Target strain, Ultrafiltration, Growth rate, Doubling time""
Research Interests:
ABSTRACT Biofouling is a crucial issue, and it causes seawater reverse osmosis membrane to deteriorate the performance of desalination. In this study, excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis... more
ABSTRACT Biofouling is a crucial issue, and it causes seawater reverse osmosis membrane to deteriorate the performance of desalination. In this study, excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) were used to monitor the strength of biofouling on the fouled membrane which was obtained from real plant. Based on EEM and PARAFAC results of raw seawater, feed water, permeate, brine and fouled membrane, three components were identified as the major peaks: (1) microbial product-like materials at Ex/Em = 280/370 nm, (2) humic-like substances at Ex/Em = 330/420 nm, and (3) aromatic proteins at Ex/Em = 240/320 nm. Using the fluorescence intensity changes, the effects of replacing fouled RO membranes were found to be most significant at one of the components (Ex/Em = 270-300/350-380 nm) which could be considered the substances desorbed from fouled RO membrane. Compared to the data for salt rejection, this component monitoring of the brine EEM image is shown to be more sensitive than conductivity monitoring for predicting the biofouling strength during the desalination process.
Research Interests:
Research Interests:
The pressure driven membrane processes of microfiltration and ultrafiltration are usually classified in terms of the size of solutes (colloids) separated. However, theoretical calculations have shown that electrostatic double-layer... more
The pressure driven membrane processes of microfiltration and ultrafiltration are usually classified in terms of the size of solutes (colloids) separated. However, theoretical calculations have shown that electrostatic double-layer interactions can have a strong influence on rejection at the pores of such membranes. The present paper provides experimental evidence to support these findings. Firstly, atomic force microscopy in conjunction with the colloid probe technique is used to measure directly the repulsive electrostatic force experienced when a single colloidal particle approaches a microfiltration membrane. Scanning of such a membrane with the colloid probe provides a direct visualisation of the membrane surface as would be experienced by a colloidal particle during filtration. Secondly, filtration flux/time data is presented for the case of filtration of particles of size very close to the pore size in an ultrafiltration membrane. For such a case, theoretical calculations allow definition of a critical pressure at which the hydrodynamic force transporting the colloid toward the membrane pore is exactly balanced by the opposing electrostatic force. The experiments show that operating above this pressure results in a rapid loss in filtration flux, but operation below this pressure allows continuing filtration with only a minor decrease in flux, in agreement with the calculations.
Research Interests:
Non-contact atomic force microscopy (AFM) has been used to investigate the furface pore structure of a polyethersulfone ultrafitration membrane of specified molecular weight cut off (MWCO) 25 000 (ES625, PCI Membrane Systems). Excellent... more
Non-contact atomic force microscopy (AFM) has been used to investigate the furface pore structure of a polyethersulfone ultrafitration membrane of specified molecular weight cut off (MWCO) 25 000 (ES625, PCI Membrane Systems). Excellent images at up to single pore resolution were obtained. This is the first time that AFM images of a membrane at such high resolution have been presented. Analysis of the images gave a mean pore size of 5.1 nm with a standard deviation of 1.1 nm. The results have been compared to previously published studies of membranes of comparable MWCO using contact AFM and electron microscopy. Non-contact AFM is a powerful means of studying the surface pore characteristics of ultrafiltration membranes.
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Non-contact atomic force microscopy has been used to investigate the surface pore structure of Cyclopore and Anopore microfiltration membranes in air. Three Cyclopore membranes and three Anopore membranes of different pore sizes were... more
Non-contact atomic force microscopy has been used to investigate the surface pore structure of Cyclopore and Anopore microfiltration membranes in air. Three Cyclopore membranes and three Anopore membranes of different pore sizes were studied. Excellent high resolution images were obtained. Analysis of the images gave quantitative information on the surface pore structure, in particular the pore size distribution. Non-contact AFM is an excellent means of obtaining such information for microfiltration membranes.
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An atomic force microscope has been used to study the electrical double layer interactions between a silicon tip (with an oxidised surface) and two polymeric membranes, one microfiltration (nominally 0.1 μm) and the other ultrfiltration... more
An atomic force microscope has been used to study the electrical double layer interactions between a silicon tip (with an oxidised surface) and two polymeric membranes, one microfiltration (nominally 0.1 μm) and the other ultrfiltration (25 000 MWCO), in aqueous NaCl solutions. Force-distance curves were measured for the two membranes at four ionic strengths. The membranes were also imaged under the same conditions using electrical double layer repulsive forces of differing magnitudes —; “electrical double layer mode” imaging. Image analysis was used to determine surface pore size distributions. The force-distance curves, together with numerically calculated potential profiles at the entrance to a charged pore, allow an explanation and identification of the optimum imaging conditions. The best images were obtained at high ionic strength with the tip close to the membrane surface.
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In this work, the pore size distributions referred to volume, surface and number of bulk pores, along with the internal surface area and the size parameters of surface pores are determined for two polyethersulphonic microporous composite... more
In this work, the pore size distributions referred to volume, surface and number of bulk pores, along with the internal surface area and the size parameters of surface pores are determined for two polyethersulphonic microporous composite membranes of nominal MWCO of 4000 and 30 000 Da. The microporous support pore size distribution has also been obtained. These goals have been achieved using several characterization techniques: atomic force microscopy (AFM), N2 adsorption-desorption at 77 K and a liquid displacement technique. A computerized analysis of the AFM micrographs allowed determination of the pore size distribution of surface pores at different magnifications. Also, surface roughness can be obtained. Adsorption isotherms, combined with the BET theory for multilayer adsorption, allowed determination of the internal surface area of the membrane, while the volume, surface and pore number distributions were calculated from the Kelvin equation, both in the desorption process to obtain the so-called mesopore distribution. Further analysis, by extending the pore size analysis to pores where the Kelvin equation is not valid, allowed determination of the micropore distribution. Finally, the membrane support has been detached and analyzed by a modified bubble point or liquid displacement technique. Analysis and comparison of all results show that several pore populations (including micro- and mesopores) are present in the membrane with considerable differences between surface pores and bulk pores, the latter being those which should determine permeation. Two further meso- and macropore populations could be assigned to the membrane-support transition or the support itself.
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The performance of a novel, hydraulically operated cell disrupter has been investigated. The micro-organism used was bakers’ yeast (Saccharomyces cerevisiae) and glucose-6-phosphate dehydrogenase (G6PDH) was used as a marker enzyme. The... more
The performance of a novel, hydraulically operated cell disrupter has been investigated. The micro-organism used was bakers’ yeast (Saccharomyces cerevisiae) and glucose-6-phosphate dehydrogenase (G6PDH) was used as a marker enzyme. The yeast could be disrupted by a single pass through the apparatus and the enzyme release was a function of the operating pressure. The equipment is considered to be superior to conventional homogeniser pumps due to the limited temperature rise observed between the feed and the lysate for comparable levels of protein release.
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In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of... more
In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of cleaning agents may result into unsatisfactory cleaning or irreparable membrane.In this study the cleaning performance has been studied with measurements of membrane contact angle, Updated Donnan steric partitioning pore model (UDSPM) and salt rejection as well as flux measurement. Thin film nanofiltration (NF) membranes such as DK, HL and DL provided by GE Osmonics are used in this study. Tests were carried out with virgin DK, HL and DL as well as fouled DK membranes. Several cleaning agents were investigated; some of them were analytical grade such as HCl, NaOH and others such as SDS, mix agents were commercial grade agents that are already in use in commercial plants. Contact angle, DSPM and salt rejection as well as flux of virgin and fouled membranes before and after chemical cleaning were measured and compared. The contact angle measurements with and without chemical cleaning of different virgin and fouled membranes revealed very interesting results which may be used to characterise the membrane surface cleanliness. The contact angle results revealed that the cleaning agents are found to modify membrane surface properties (hydrophobicity/hydrophilicity) of the treated and untreated virgin and fouled membranes. The details of these results were also investigated and are reported in the paper. However, UDSPM method did not give any valuable information about pore size of the untreated and treated NF membranes. The salt rejection level of monovalent and divalent ions before and after cleaning by high and low pH cleaning agents is also investigated and is reported in the paper.
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The binding and retention of single metal ions and mixtures of metal ions with polyethylenimine (PEI) was studied using polymer enhanced ultrafiltration (PEUF). Using a highly branched chain form of PEI (Sigma Aldrich 181979) with an... more
The binding and retention of single metal ions and mixtures of metal ions with polyethylenimine (PEI) was studied using polymer enhanced ultrafiltration (PEUF). Using a highly branched chain form of PEI (Sigma Aldrich 181979) with an average molecular weight 750,000 and approximately 60,000, ultrafiltration experiments were carried out in the stirred dead-end ultrafiltration mode. The results of the binding studies show that the Langmuir isotherm offers a good description of the binding process. At pH 5.5, the maximum polymer binding (Q max) and binding affinity constant (K L) were determined according to Langmuir isotherms. It was observed that the maximum amount of metal ions bound to the polymer for Cu2+, Zn2+, Ni2+ and Cd2+ decreased substantially in solutions containing mixtures of metal ions when compared to the values obtained for single metal ion solutions. For Cr6+ and Co2+ no significant decrease was seen. These data indicate that the binding capacity of Cr6+ and Co2+ remain constant in competition while Cu2+, Zn2+, Ni2+ and Cd2+ show changes in both binding capacity and equilibrium constant. The effectiveness of the polymer enhanced ultrafiltration (PEUF) process was shown to be heavily dependent on the concentration of competing metal ions, influencing both capacity and selectivity of the polymer. These findings suggest that the effectiveness of metal binding needs to be determined in the specific water to be treated before the PEUF system can be designed.
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Polymer enhanced ultrafiltration (PEUF) was used to study the retention and flux of aqueous solutions of heavy metals. The metal ions investigated were: Cu2+, Zn2+, Ni2+, Cr6+, Co2+ and Cd2+. For each metal solution, stirred dead-end... more
Polymer enhanced ultrafiltration (PEUF) was used to study the retention and flux of aqueous solutions of heavy metals. The metal ions investigated were: Cu2+, Zn2+, Ni2+, Cr6+, Co2+ and Cd2+. For each metal solution, stirred dead-end ultrafiltration experiments were performed in the presence and absence of polyethylenimine (PEI) at different pHs. Addition of PEI significantly affected both the retention of the metal ions and the flux of the filtration process. In the absence of PEI, significant rejection of metals only occurred at higher pH values. This can be attributed to the formation of insoluble metal compounds (hydroxides) at pH 6 or greater. In the presence of PEI the retention was greater than the retention without PEI due to the formation of metal/ polymer complexes. This retention was also sensitive to pH with higher values of retention at near neutral or slightly acidic conditions. Although a reduction of flux due to the addition of PEI was anticipated (the flux was reduced by about 50% when compared to the reference solution) the addition of small quantities of metals to the reference solution also signifi cantly affected the flux. Membrane charge properties also play a significant role in the rejection and flux of the metal ion/polymer solutions.
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Microbial conversion of syngas to energy-dense biofuels and valuable chemicals is a potential technology for the efficient utilization of fossils (e.g., coal) and renewable resources (e.g., lignocellulosic biomass) in an environmentally... more
Microbial conversion of syngas to energy-dense biofuels and valuable chemicals is a potential technology for the efficient utilization of fossils (e.g., coal) and renewable resources (e.g., lignocellulosic biomass) in an environmentally friendly manner. However, gas-liquid mass transfer and kinetic limitations are still major constraints that limit the widespread adoption and successful commercialization of the technology. This review paper provides rationales for syngas bioconversion and summarizes the reaction limited conditions along with the possible strategies to overcome these challenges. Mass transfer and economic performances of various reactor configurations are compared, and an ideal case for optimum bioreactor operation is presented. Overall, the challenges with the bioprocessing steps are highlighted, and potential solutions are suggested. Future research directions are provided and a conceptual design for a membrane-based syngas biorefinery is proposed.
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Research Interests: Carbon Dioxide, Biomass, Performance Assessment, Multidisciplinary, Growth Kinetics, and 15 moreGlucose, Bacteria, Malolactic Fermentation, Fructose, Growth performance, Gram Positive Bacteria, Fermentation, Applied Microbiology and Biotechnology, Culture Media, Continuous Culture, Lactic Acid, Hydrogen-Ion Concentration, Specific Growth Rate, pH control, and Dry Weight
Nanofiltration membranes play an important role in the desalination of brackish and seawater as well as membrane mediated waste water reclamation and other industrial separations. Fouling of nanofiltration (NF) membranes is typically... more
Nanofiltration membranes play an important role in the desalination of brackish and seawater as well as membrane mediated waste water reclamation and other industrial separations. Fouling of nanofiltration (NF) membranes is typically caused by inorganic and organic materials present in water that adhere to the surface and pores of the membrane and results in deterioration of performance (reduced membrane flux) with a consequent increase in costs of energy and membrane replacement.Natural organic matter (NOM) fouling of NF membranes involves interrelationship between physical and chemical interactions and is described in this review. Inorganic fouling due to scale formation of sparingly soluble inorganic salts occurs whenever the ionic salt concentration stream exceeds the equilibrium solubility. Scale formation takes place by homogenous or heterogeneous crystallization mechanisms. Biofilm formation also becomes an issue when its thickness and surface coverage reduces permeability.There are two strategies that are usually employed to minimize the effect of fouling. The first group includes minimizing of fouling by using adequate feed pretreatment, membrane treatment and membrane modification. The second group involves membrane remediation by chemical cleaning which is carried out to restore membrane fluxes.A large number of chemical cleaning agents are commercially available, and the commonly used ones fall into six categories: alkalis, acids, metal chelating agents, surfactants, oxidation agents and enzymes. In general, these cleaning agents do improve the membrane flux to certain extent. Combination of these chemical agents has also been tried in order to improve the flux restoration. Even though, many of these cleaning agents can restore the flux over 100% (enhanced flux), they can also impair the selectivity of the membrane reducing of the product water quality.There are many traditional assessment methods for cleaning and at present these are being supplemented by methods using modern surface analysis techniques. These are being now rapidly developed to give a more precise assessment and a better understanding of cleaning processes. Generally, cleaning is assessed by flux, zeta potential measurement, atomic force microscope (AFM) and Fourier transforms infrared technique (FTIR). Atomic force microscope and related techniques are particularly employed in order to evaluate the cleaning efficiency and other surface phenomena.There are several factors that can affect the chemical cleaning process which include temperature, pH, concentration of the cleaning chemicals, contact time between the chemical solution and the membrane and the operation conditions such as cross-flow velocity and pressure. The role of temperature and pH in cleaning are membrane dependent. These factors play very important role in flux recovery. A critical review of these factors is also presented.It appears from the literature that only very few papers on cleaning of NF membrane to regenerate membrane performance have been published up to date, and there is an urgent need for extensive research work to investigate fouling mechanisms in order to obtain fundamental understanding of fouling to provide more feasible, cost-effective cleaning and performance restoration procedures. This also provides further strategies for the avoidance of fouling through better pretreatment and more appropriate membrane fabrication and modification.
Research Interests: Engineering, Membrane Science, Water quality, Nanofiltration, Cost effectiveness, and 12 moreEnzyme, CHEMICAL SCIENCES, Waste Water, Operant Conditioning, Atomic Force Microscope, Flow Velocity, Water Quality, Surface Analysis, Zeta Potential, Assessment Methods, Natural Organic Matter, and Fourier transform infrared
In the membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. The characterisation of membrane surface by using zeta potential technique provides a more... more
In the membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. The characterisation of membrane surface by using zeta potential technique provides a more appropriate tool to study the cleaning performance and membrane integrity. The use of zeta potential technique to characterize the cleaning effect on membrane surfaces has very little precedence in literature.In this study the cleaning performance has been studied with membrane zeta potential and hydraulic permeability measurement. Virgin nanofiltration (NF) membranes provided by GE Osmonics (DK, HL and DL), as well as fouled DK membranes were used in this study. Several cleaning agents were investigated, some of them were analytical grade, such as HCl, NaOH and others were commercial grade agents that are already in use in commercial plants. Zeta potential of virgin and fouled NF membranes before and after chemical cleaning were measured and compared. The results of the zeta potential measurements with and without chemical cleaning of virgin and fouled membrane indicated that zeta potential may be used to characterise the membrane surface cleanliness and permeability. The effects of temperature, pH and the cleaning agents on membrane zeta potential were also investigated. The temperature was not found to have any significant effect on membrane zeta potential; however, the effect of pH and cleaning agents had pronounced effects on the surface charge and zeta potential.At high pH values mixed cleaning agents of mixture of trisodium phosphate, sodium tripolyphosphate and EDTA (recommended by membrane manufacturer) had a marked effect on zeta potential of HL and DL membranes compared to other cleaning agents. A DK fouled membrane was found to be almost negatively charged with no isoelectric point compared to a virgin DK membrane. At low pH, the zeta potential values of a fouled DK membrane were in close agreement with those obtained with an untreated virgin membrane after cleaning by NaOH followed by HCl.The zeta potential of all virgin membranes cleaned with SDS changed to more negative for the entire pH range compared to untreated virgin membranes. The study revealed that the SDS cleaning agent had the highest effect on surface charge for both virgin and fouled NF membranes.
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A mechanistic model of microalgae is used to explore the implications of modifying microalgal chlorophyll content and photosynthetic efficiency with an aim to optimising commercial biomass production. The models show the potential for a... more
A mechanistic model of microalgae is used to explore the implications of modifying microalgal chlorophyll content and photosynthetic efficiency with an aim to optimising commercial biomass production. The models show the potential for a 10 fold increase in microalgae productivity in genetically modified versus unmodified configurations, while also enabling the use of bioreactors of greater optical depth operating at lower dilution rates. Analysis suggests that natural selection of a trait benefiting the individual (high Chl:Cmax, i.e., high antennae size) conflicts with artificial selection of a trait (low Chl:Cmax) of most benefit to production at the population level. The implication is that GM strains rather than strains selected from nature will be most beneficial for commercial algal biofuels production. Further, escaped GM algae populations may, depending on the specific nature of the modification, be quickly out-competed by the natural forms because individually a high Chl:C is beneficial in low light environments. However, it remains possible that changes in biochemical composition associated with genetic modification of photosystem competence, or with other selection processes to enhance commercial gain, may adversely affect the value of such organisms as prey for zooplankton, leading to the unwanted generation of future harmful algae.
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Aims: To study the effect of sugars and sugar mixtures on the growth kinetics of Oenococcus oeni NCIMB 11648 in batch culture with the aim of producing a high cell productivity system for starter cultures.Methods and Results: The growth... more
Aims: To study the effect of sugars and sugar mixtures on the growth kinetics of Oenococcus oeni NCIMB 11648 in batch culture with the aim of producing a high cell productivity system for starter cultures.Methods and Results: The growth of O. oeni was investigated on single sugars (glucose, fructose or sucrose) and their mixtures (glucose–fructose, glucose–sucrose or fructose–sucrose). Better growth was obtained on sugar mixtures compared with growth on a single sugar. The production system of O. oeni biomass was investigated in batch culture with or without pH control with respect to kinetics, specific growth rate and biomass yield. The effect of pH and substrate concentration on fermentation balances and ATP yield were determined. The optimal growth of O. oeni was achieved on the glucose–fructose mixture (9 g l−1, 1 : 1) at pH 4·5 and 25°C with pH control, with highest cell volumetric productivity (7·9 mg cell l−1 h−1), biomass yield (0·041 g cell g−1 sugar) and specific growth rate (0·066 h−1).Conclusions: The limitations to the growth of O. oeni were pH and inhibition by end product resulting in poor utilization of the medium with low cell yields. The cell productivity of the system can be improved by the appropriate use of mixed sugar growth medium.Significance and Impact of the Study: This study uniquely showed that appropriate sugar mixtures with the correct environmental conditions can significantly improve the productivity of O. oeni cultures.
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... Permissions & Reprints. Chapter 14 Ab initio prediction of the performance of membrane separation processes. W. Richard Bowen a , Nidal Hilal a , Mohit Jain a , Robert W. Lovitt a , A. Wahab Mohammad a , Adel O. Sharif a , Chris... more
... Permissions & Reprints. Chapter 14 Ab initio prediction of the performance of membrane separation processes. W. Richard Bowen a , Nidal Hilal a , Mohit Jain a , Robert W. Lovitt a , A. Wahab Mohammad a , Adel O. Sharif a , Chris J. Wright a and Paul M. Williams b. ...
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An atomic force microscope (AFM) has been used to quantify directly the adhesive interactions between a silica sphere and a planar silica surface. Electrostatic double-layer interactions have also been quantified through analysis of... more
An atomic force microscope (AFM) has been used to quantify directly the adhesive interactions between a silica sphere and a planar silica surface. Electrostatic double-layer interactions have also been quantified through analysis of approach curves. The surfaces of the sphere and ...
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Spent digester effluents were formulated into nutrient media , suitable for microbial growth of industrially important microorganisms, using filtration and diafiltration. The waste effluents were pretreated by dilution, sedimentation and... more
Spent digester effluents were formulated into nutrient media , suitable for microbial growth of industrially important microorganisms, using filtration and diafiltration. The waste effluents were pretreated by dilution, sedimentation and sieving for the removal of large particulate material. The scheme used allowed the successful formulation particle, free sterile effluents, with an N:P ratio 36.6 The prepared microfiltered effluents were then physicochemically characterized before being assessed for their utilization as growth substrates of microorganism associated with chemical and fuels production. Microfiltered treated digested propagated with Escherichia coli NCIMB 8277, agricultural sludge based media were compared with in vitro media when supplied with or without addition carbohydrate sources. in bench scale batch aerobic. Good growth was achieved compared to synthetic growth media with the microorganism using filtrates. When the treated effluents were supplied with 2 % w/v glucose solution a significant improvement in the growth rates and growth yields was achieved giving comparable performance with the synthetic media.
Keywords: microfiltration, anaerobic digestion, sludge, nutrient media, bacterial growth, biofuels, acid, wastewater treatment
Keywords: microfiltration, anaerobic digestion, sludge, nutrient media, bacterial growth, biofuels, acid, wastewater treatment