Bacterial Adhesion

Treatment of wastewater at secondary stage is dependent on microbial activity for removal of soluble organic pollutants, which is challenging in case of industrial wastewater. There are certain organic compounds in this wastewater which are recalcitrant or degraded scarcely, including aromatic hydrocarbon pollutants. Hence, it is challenging to achieve the desired standard limit for safe effluent discharge. In the present study, a novel bacterial consortium produced high and steady voltage output (0.6 V) and a moderate level of exopolysaccharide, comprised of Stenotrophomonas maltophilia KO014, Bacillus subtilis EPS040, Pseudomonas stutzeri EPS026 and Shewanella xiamenensis KRTO021, which could successfully develop biofilm on electrode surface. Microbial fuel cell reduced chemical oxygen demand (COD) and biochemical oxygen demand (BOD) up to 49.9 % (1098 ppm to 550 ppm) and 47.6 % (447 ppm to 234 ppm) respectively from synthetic wastewater containing sodium benzoate as model aromatic hydrocarbon pollutant. Barium ferrite (BaFe 12 O 19) NPs synthesized using Moringa oleifera flower has excellent multiferroic properties and show photocatalytic degradation capacity due to its optical band gap (2.18 eV) which falls within visible range. Hence, it could act as photocatalyst under visible light and could further reduce the residual COD and BOD levels of MFC treated water by 44 % (550 ppm to 308 ppm) and 65.8 % (234 ppm to 80 ppm) respectively emphasizing its useful application as non-biological treatment method for further removal of residual SB present in MFC treated water.

Listeria monocytogenes, an intracellular foodborne pathogen, infects immunocompromised hosts. The primary route of transmission is through contaminated food. In the gastrointestinal tract, it traverses the epithelial barrier through intracellular or paracellular routes. Strategies to prevent L. monocytogenes entry can potentially minimize infection in high-risk populations. Listeria adhesion protein (LAP) aids L. monocytogenes in crossing epithelial barriers via the paracellular route. The use of recombinant probiotic bacteria expressing LAP would aid targeted clearance of Listeria from the gut and protect high-risk populations from infection. The objective was to investigate the ability of probiotic bacteria or LAP-expressing recombinant probiotic Lactobacillus paracasei (Lbp(LAP)) to prevent L. monocytogenes adhesion, invasion, and transwell-based transepithelial translocation in a Caco-2 cell culture model. Several wild type probiotic bacteria showed strong adhesion to Caco-2 cel...

Background Streptococcus mutans is known as a key causative agent of dental caries. It metabolizes dietary carbohydrate to produce acids which reduce the environmental pH leading to tooth demineralization. The ability of this bacterium to tolerate acids coupled with acid production, allows its effective colonization in the oral cavity leading to the establishment of highly cariogenic plaque. For this reason, S. mutans is the only bacterium found in significantly higher numbers than other bacteria in the dental plaque. The aim of this study was to evaluate the effect of crude extract and methanolic fraction of Z. officinale against S. mutans virulence properties.ResultsWe investigated in vitro and in vivo activity of crude extract and methanolic fraction at sub- MIC levels against cariogenic properties of S. mutans. We found that these extracts strongly inhibited a variety of virulence properties which are critical for its pathogenesis. The biofilm formation in S. mutans was found to...

Backfilling a self-assembled monolayer (SAM) of long poly (ethylene glycol) (PEG) with short PEG is a well-known strategy to improve its potential to resist fouling. Here it is shown, using xray photoelectron spectroscopy, contact angle, and atomic force microscopy, that backfilling PEG thiol with oligo (ethylene glycol) (OEG) terminated alkane thiol molecules results in underbrush formation. The authors also confirm the absence of phase separated arrangement, which is commonly observed with backfilling experiments involving SAMs of short chain alkane thiol with long chain alkane thiol. Furthermore, it was found that OEG addition caused less PEG desorption when compared to alkane thiol. The ability of surface to resist fouling was tested through serum adsorption and bacterial adhesion studies. The authors demonstrate that the mixed monolayer with PEG and OEG is better than PEG at resisting protein adsorption and bacterial adhesion, and conclude that backfilling PEG with OEG resultin...

Probiotic industries strive for new, efficient and promising probiotic strains that impart a positive impact on consumer health. Challenges are persisting in isolation, screening, and selection of the new indigenous probiotic strains. In the present research, we explored the probiotic potential of 17 lactic acid bacteria isolated from Yak milk in a series of in vitro tests. We also demonstrated their health benefits, i.e., cholesterol degradation, lactose digestion, antimicrobial activity, antioxidant, and anticancer activities. Principal component analysis revealed that more than 50% of the strains fulfilled the examined criteria, e.g., survival in acidic pH, bile concentrations, and adherent property. Approximately all the strains produced antimicrobial substances against the maximum number of tested strains including clinical strains. Most strains degraded cholesterol in comparison to the reference probiotic strain whereas strain Yc showed 1.5 times higher the degradation efficie...

Understanding biological interaction with graphene and hexagonal-Boron Nitride (h-BN) membranes has become essential for the incorporation of these unique materials in contact with living organisms. Previous reports show contradictions regarding the bacterial interaction with graphene sheets on metals. Here we present a comprehensive study of the interaction of bacteria with copper substrates coated with single layer graphene and h-BN. Our results demonstrate that such graphitic coatings substantially suppress interaction between bacteria and underlying Cu substrates, acting as an effective barrier to prevent physical and electrical contact between bacteria, which do not "feel" the strong antibacterial effect of Cu, and metal that do not suffer biocorrosion due to bacteria contact. Effectiveness of these systems as barriers can be understood in terms of graphene and h-BN impermeability to transfer Cu+2 ions, even when graphene and h-BN domain boundary defects are present. ...

Background Phospholipase B (PLB) has been reported to be one of the virulence factors for human pathogenic fungi and has also been described as necessary for the early events in infection. Based on these data, we investigated the role of PLB in virulence and modulation of the alveolar pulmonary immune response during infection using an in-vitro model of host-pathogen interaction, i.e. Paracoccidioides brasiliensis yeast cells infecting alveolar macrophage (MH-S) cells. Results The effect of PLB was analyzed using the specific inhibitor alexidine dihydrochloride (0.25 μM), and pulmonary surfactant (100 μg mL-1), during 6 hours of co-cultivation of P. brasiliensis and MH-S cells. Alexidine dihydrochloride inhibited PLB activity by 66% and significantly decreased the adhesion and internalization of yeast cells by MH-S cells. Genes involved in phagocytosis (trl2, cd14) and the inflammatory response (nfkb, tnf-α, il-1β) were down-regulated in the presence of this PLB inhibitor. In contra...

Hyperthermophiles are microorganisms that thrive in extremely hot environments with temperatures near and even above 100 (°) C. They are the most deeply rooted microorganisms on phylogenetic trees suggesting they may have evolved to survive in the early hostile earth. The simple respiratory systems of some of these hyperthermophiles made them potential candidates to develop microbial fuel cells (MFC) that can generate power at temperatures approaching the boiling point. We explored extracellular electron transfer ability of a hyperthermophilic archaeon Pyrococcus furiosus (Pf) by studying its ability to generate electricity in a two-chamber MFC. Pf growing in defined medium functioned as an anolyte in a MFC operated at 90 (°) C, generating a maximum current density of 2 A m(-2) and a peak power density of 225 mW m(-2) without the addition of any external redox mediator. Electron microscopy and electrochemical impedance spectroscopy of the anode with the attached Pf biofilm demonstra...

Bifidobacteria represent one of the dominant groups of microorganisms colonizing the human infant intestine. Commensal bacteria that interact with a eukaryotic host are believed to express adhesive molecules on their cell surface that bind to specific host cell receptors or soluble macromolecules. Whole-genome transcription profiling of Bifidobacterium bifidum PRL2010, a strain isolated from infant stool, revealed a small number of commonly expressed extracellular proteins, among which were genes that specify sortase-dependent pili. Expression of the coding sequences of these B. bifidum PRL2010 appendages in nonpiliated Lactococcus lactis enhanced adherence to human enterocytes through extracellular matrix protein and bacterial aggregation. Furthermore, such piliated L. lactis cells evoked a higher TNF-α response during murine colonization compared with their nonpiliated parent, suggesting that bifidobacterial sortase-dependent pili not only contribute to adherence but also display ...

The purpose of this study was to isolate and identify the microbes from hospital environmental samples and to evaluate the potential of biofilm formation by isolated microbes. For this, 125 surface swabs of different environmental samples were taken from PNS SHIFA hospital, Karachi, Pakistan. Bacteria and fungi were isolated and identified by culture plate method. Trypticase soy broth (TBS) media was used for biofilm development by microbes in plastic tubes. Developed biofilm in tubes was visualized with crystal violet staining method and then biofilm forming potential was estimated by measuring the optical density through spectrophotometer. Total 202 microbes including 126(62.38%) bacteria and 76(37.62%) fungi were isolated and identified. Among environmental samples, hospital ward curtains and medical trays were highly contaminated with bacteria and fungi (with 26% each of total assemblage respectively). Staphylococcus aureus was in highest abundance followed by Candida albicans w...

The expression of flagella correlates with different aspects of bacterial pathogenicity, ranging from adherence to host cells to activation of inflammatory responses by the innate immune system. In the present study, we investigated the role of flagella in the adherence of an atypical enteropathogenic Escherichia coli (aEPEC) strain (serotype O51:H40) to human enterocytes. Accordingly, isogenic mutants deficient in flagellin (FliC), the flagellar structural subunit; flagellar cap protein (FliD); or MotAB proteins, involved in the control of flagellar motion, were generated and tested for binding to differentiated Caco-2 cells. Binding of the aEPEC strain to enterocytes was significantly impaired in strains deleted of fliC and fliD genes, both of which could not form flagella on the bacterial surface.A non-motile, but flagellated, MotAB mutant also showed impaired adhesion to Caco-2 cells. In accordance with these observations, adhesion of the aEPEC 1711-4 strain to Caco-2 cells was ...

SummaryEncapsulation is thought to be a critical virulence factor for Streptococcus suis. In this study, encapsulation of a selected S. suis culture could be stimulated by cultivation conditions. After cultivation of the S. suis culture in fluid media supplemented with serum, the culture grew with short chains and a uniform turbidity of the growth medium. Autoclave extracts of this culture reacted with capsular type‐1‐specific antiserum. After cultivation of the S. suis culture in fluid media without serum, the bacteria generally formed longer chains, grew in fluid medium as granular sediment with clear supernatant, and were non‐typeable. In addition, the unencapsulated variant appeared to have a more hydrophobic surface and adhered significantly more to HeLa cells. In contrast to the unencapsulated variant, the encapsulated S. suis was phagocytosed to a lesser extent by polymorphonuclear leucocytes. These findings might help to elucidate the role of encapsulation in infections with...

A total of 128 bovine and 134 human group B streptococci were serotyped by conventional methods. Among the bovine cultures, 60 (47%) had type antigen X, and among the human cultures, 53 (39%) had type antigen R. The occurrence of type antigens X and R was significantly related to the growth pattern of the bacteria in fluid media. Type X- and R-positive cultures and most of the nontypeable cultures predominantly formed long chains and grew as granular sediment with clear supernatant. In addition, group B streptococci with surface antigen X or R showed compact colony formation in soft agar and reacted positively in the salt aggregation test. These properties, possibly caused by the surface charges of the X- and R-positive cultures, might be related to bacterial pathogenicity.

Vibrio parahaemolyticus expresses one major virulence determinant T6SS2, which is constituted into three putative operons, i.e., VPA1027-1024, VPA1043-1028, and VPA1044-1046. CalR, a LysR-type transcriptional regulator, was originally identified as a repressor of the swarming motility and T3SS1 gene expression. As shown in this study, CalR binds to the promoter-proximal region of each of the three operons to activate their transcription, and moreover, CalR activates the adhesion of V. parahaemolyticus to HeLa cells. In addition, competitive EMSAs demonstrated that CalR acts as an antagonist of H-NS in V. parahaemolyticus. Collectively, these studies confirmed a new physiological role for CalR in V. parahaemolyticus.

The interaction between the macrophage and Mycobacterium tuberculosis is mediated by a variety of macrophage membrane-associated proteins. Complement receptors have been implicated in the adherence of M. tuberculosis to macrophages. In the present work, the adherence and/or ingestion of M. tuberculosis H37Rv to human monocyte-derived macrophages (MDM) from patients with tuberculosis (TB) and healthy controls was measured by microscopical examination, [ 3 H]uracil incorporation, and CFU. The adherence and/or ingestion was enhanced by fresh serum and inhibited by heat inactivation, EDTA treatment, and anti-CR1 and anti-CR3 antibodies. Comparison of MDM from TB patients and healthy controls showed that the former exhibited a significantly decreased capacity to adhere and/or ingest M. tuberculosis , as determined by the number of CFU and 3 H incorporation. The expression of CR1 (CD35) and CR3 (CD11b/CD18) on MDM from TB patients and healthy controls, as determined by flow cytometry, did...

Brazilian purpuric fever (BPF) is a fulminant pediatric disease characterized by fever, with rapid progression to purpura, hypotensive shock, and death. All known BPF cases have been caused by three clones of Haemophilus influenzae biogroup aegyptius and have occurred in either Brazil or Australia. Using an immortalized line of human vascular endothelial cells, we developed an in vitro assay that identifies all known BPF-causing H. influenzae biogroup aegyptius strains (R. S. Weyant, F. D. Quinn, E. A. Utt, M. Worley, V. G. George, F. J. Candal, and E. W. Ades, J. Infect. Dis. 169:430-433, 1994). With multiplicities of infection (MOIs) as low as one bacterium per 1,000 tissue culture cells, BPF-associated strains produce a unique cytotoxic effect in which the tissue culture cells detach and aggregate in large floating masses after 48 h of incubation. In this study, using a BPF-associated strain and a non-BPF-associated control, we demonstrated that strains which produce the cytotoxi...

The capsular polysaccharide of Streptococcus pneumoniae represents an important virulence factor and protects against phagocytosis. In this study the amount of capsular polysaccharide present on the bacterial surface during the infection process was illustrated by electron microscopic studies. After infection of A549 cells (type II pneumocytes) and HEp-2 epithelial cells a modified fixation method was used that allowed visualization of the state of capsule expression. This modified fixation procedure did not require the use of capsule-specific antibodies. Visualization of pneumococci in intimate contact and invading cells demonstrated that pneumococci were devoid of capsular polysaccharide. Pneumococci not in contact with the cells did not show alterations in capsular polysaccharide. After infection of the cells, invasive pneumococci of different strains and serotypes were recovered. Single colonies of these recovered pneumococci exhibited an up-to-10 5 -fold-enhanced capacity to ad...

This study was carried out to detect the distribution of antibiotic resistant genes in Escherichia coli isolated from chickens by whole genome sequencing. Isolation of E. coli from chicken confirmed by biochemical test. This investigated genes included ampC, acrF, bacA, rarD, tehB, bcr, fsr, emrE were resistant to single antimicrobial agent and emrD, marR, marA, marB, mdtK, emrY, emrK, emrA, emrB were multi-resistance. Multi-resistance which was defined as resistance to two or more tested agents. Whole genome sequencing and strategy to identify resistant genes reveals the presence of multidrug resistant genes for above tested antibiotics.