Lactobacilli

Probiotics including Lactobacillus, Bifidobacteria, Enterococcus, Streptococcus, Bacillus, Lactococcus and some yeasts are usually present in the human gastrointestinal tract, fermented milk and other dairy products, human faeces and breast milk. Source of strains and the ability to reach the target site in the gastrointestinal tract are important. Strains must be able to survive on different physiochemical, enzymatic and microbial stresses throughout the gastrointestinal transit before they can exhibit beneficial effects on the host's health. They can improve the intestinal microbial equilibrium and stimulate butyrate production, which promotes the growth of epithelial cells that lead to an increase in the thickness of the cecal and colonic mucosa for a better absorption of nutrients. They also produce a variety of metabolic end products with antagonistic properties against pathogens. These products include bactericidal proteins and antibiotic-like metabolites termed bacteriocins (such as nisin). The inhibitory spectra of several bacteriocins include food spoilage microorganisms and/or food-borne pathogens. Bacteriocins are considered to be safe natural preservatives or bio-preservatives because it is assumed that they can be degraded by the proteases present in the gastrointestinal tract. The joint working group of Food Aid Organization/World Health Organization made guidelines that can be used for assessing probiotics in food. The minimum requirements include assessment of strain identity and safety, and studies of health benefits in the target host. The continuous search for novel probiotics of importance in medical, industrial and agricultural environments is ongoing around the word. This review summarizes the current state of evaluation criteria for determining the candidacy of novel probiotics.

A number of studies involving the feeding of probiotics and prebiotics to infants have been published over the last decade. These studies have examined a wide range of health outcomes, including growth and safety, prophylaxis and alleviation of diarrheal disease, reduction in atopic disease, reduction in necrotizing enterocolitis, and reduction in infection of the preterm infant. In addition, these studies have described microbiological alterations observed in response to probiotic and prebiotic feeding. Collectively, the reports demonstrate that probiotics show considerable promise in addressing several health outcomes of significance to both formula-fed and breastfed infants. As quantitative and qualitative differences appear to exist between the microfloras of human-milk fed and formula-fed infants, recent innovations to infant formula have involved the inclusion of probiotics and prebiotics as a means of making the flora of the formula fed infant more similar to that of the breastfed infant. To date, only a few probiotic- and prebiotic-containing infant formulas have been marketed, but as new safety and efficacy data emerge and the regulatory climate becomes more favourable, the number of products is expected to grow.

This study aimed to evaluate the long-term effect of the topical use of an iodine agent on the salivary
mutans streptococci (MS) and lactobacilli (LB) and compare it with the professionally applied topical
fluoride. The study included 54 children with high caries activity. Children received one application
of topical fluoride gel (APF) then they were divided into two groups. In group I, twenty seven patients
received topical application of fluoride gel weekly for 4 weeks followed by one application of fluoride
gel every 3 months for one year. For group II, 10% povidone iodine was carried out weekly for 4 weeks
for 27 patients followed by alternative applications of fluoride gel or povidone iodine every 3 months
for one year. Bacteriological evaluation was done at base line, after 1, 3, 6 and 12 months. Saliva samples
were grown on selective culture media. The differences between the two groups were evaluated at
the end of the study. Drop out of patients was reported throughout the different evaluation periods.
The results were evaluated statistically and showed no statistical significant difference between the two
groups. It is concluded that iodine solution reduced the number of caries related microorganisms as
compared to the base line. Antimicrobial approaches need more studies to confirm the findings and
optimize the regimens.

Objective
Studies on lactic acid bacteria exemplify their use against various enteropathogens in vitro. Nevertheless, in vivo effects of Lactobacillus during Shigella infection have not been evaluated. The present study evaluated the effect of Lactobacillus rhamnosus and Lactobacillus acidophilus on neutrophil infiltration and lipid peroxidation during Shigella dysenteriae 1–induced diarrhea in rats.

Methods
The rats were divided into eight groups (n = 6 in each group). Induced rats received single oral dose of S. dysenteriae (12 × 108 colony-forming units [cfu]/mL). Treated rats received L. rhamnosus (1 × 107 cfu/mL) or L. acidophilus (1 × 107 cfu/mL) orally for 4 d, alone or in combination, followed by Shigella administration. At the end of the experimental period, animals were sacrificed and the assay of the activity of alkaline phosphatase, myeloperoxidase, and antioxidants and the estimation of lipid peroxides were performed. Activity staining of superoxide dismutase and catalase was done in addition to gelatin zymography for matrix metalloproteinase (MMP; MMP-2 and MMP-9) activity. A portion of the intestinal tissue was fixed in 10% formalin for histologic studies.

Results
Administration of S. dysenteriae 1 alone resulted in increased levels of myeloperoxidase, lipid peroxidation, alkaline phosphatase, and the expression of MMP-2 and MMP-9 with concomitant decrease in the antioxidant levels. Pretreatment with the combination of L. rhamnosus (1 × 107 cfu/mL) and L. acidophilus (1 × 107 cfu/mL) significantly attenuated these changes when compared with the diseased group. Histologic observations were in correlation with biochemical parameters.

Conclusion
Lactobacillus rhamnosus plus L. acidophilus offered better protection when compared with individual treatment with these strains during Shigella infection

The presence of ochratoxin A (OTA) in cocoa beans is a major health concern, due to its deleterious effects on humans and animals. During the traditional processing and storage of cocoa, fungi contamination occurs. Many of these fungi, produce mycotoxins that can cause acute or chronic intoxication and damage to human and animals after ingestion of the contaminated food and feed. The bio-control of ochratoxigenic moulds by lactic acid bacteria (LAB) could provide a safer alternative compared to the use of fungicides. The present study aims at investigating the potential of selected lactobacilli strains to inhibit the growth of OTA producing moulds. Cocoa samples were collected in the South West region of Cameroon. The mycoflora of cocoa beans were isolated and identified using phenotypic characteristics on Potato Dextrose Agar (PDA) and microscopy after application of lactophenol cotton blue stain. LAB used were isolated from fermented palm and raffia wines and fermented pineapple juice by pour plate method on De Man Rogosa and Sharpe Agar. Phenotypic identification of LAB were identified using API 50 CHL kit. Colony PCR was used to confirm whether the isolates belong to LAB group. The inhibitory activity of Lactobacillus sp against ochratoxigenic moulds was carried out on agar using the overlay method and in broth by turbidimetric analysis. Aspergillus sp were the most prevalent fungi in cocoa samples. Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger were isolated in all samples. Lactobacillus. plantarum exhibited the highest inhibitory activity against OTA producing moulds. The percentage of inhibition was ranged from 10 to 46.5%. A. ochraceus was the most susceptible mould with the various LAB isolates. The quantification of OTA using ELISA kit showed significant reduction in OTA production (p<0.05) during mixed culture of moulds with lactobacilli. Lactobacilli from fermented drinks could be used for biological control of OTA producing fungi.

Objective
Shigella dysenteriae Type 1 dysentery is a major cause of morbidity and mortality in children from less developed and developing countries. The present study explores the hypothesis that lactobacilli protect the host cell during S. dysenteriae Type 1 infection and its mechanism of action.

Methods
Caco-2 cells incubated for 1 h with Lactobacillus rhamnosus or Lactobacillus acidophilus at the multiplicity of infection of 100, either alone or in combination followed by addition of Shigella at the same multiplicity of infection for 5 h served as treatment groups. Cells incubated with Shigella without lactobacilli addition served as infected cells. At the end of experimental period, cells were processed suitably to enumerate adherent and internalized Shigella. Reverse transcription-polymerase chain reaction was performed to assess mRNA expression of interleukin-8 and tumour necrosis factor-α. Immunoblot for heat shock protein-70 and cytotoxicity assay were performed.

Results
Pretreatment with the combination of lactobacilli significantly (p < 0.05) prevented adherence and internalization of Shigella coupled with reduced expression of tumour necrosis factor-α and interleukin-8 in host cells.

Conclusion
L. rhamnosus and L. acidophilus, synergistically offered better protection during S. dysenteriae Type 1 infection by efficiently inhibiting adherence and internalization of Shigella coupled with inhibition of pro-inflammatory response.

Probiotics means “for life”. Probiotics are naturally occurring beneficial organisms that aid in digestion and inhibit disease-causing bacteria in the intestine. Due to the beneficial impact of microorganism used as Probiotics; during the last decades progressive attention has been focused on biological and molecular characterization and improvement of such microbes during the last decades. Probiotics in the strictest sense, refers to lactic acid producing bacteria Most data accumulated so far have related that lactic acid bacteria are major organisms, which that when given orally will pass through the strong acid of the stomach and the low surface tension of bile and colonize in the intestine, which is their normal habitat. Lactic acid bacteria mainly include Lactobacilli and Bifidobacteria. Various studies have indicated that lactobacillus species may have a positive influence on the intestinal flora of human, alleviate lactose intolerance, have hypocholesterolemic effect, stimula...

Lactobacilli are probiotic commensal bacteria and potent modulators of immunity. When present in the gut or supplemented as probiotics, they beneficially modulate ex vivo immune responsiveness. Further, factors derived from several lactobacilli strains act immune regulatory in vitro. In contrast, Staphylococcus aureus (S. aureus) is known to induce excessive T cell activation. In this study, we aimed to investigate S. aureus-induced activation of human mucosal-associated invariant T cells (MAIT cells), γδ T cells, NK cells, as well as of conventional CD4 + and CD8 + T cells in vitro. Further, we investigated if lactobacilli-derived factors could modulate their activation. PBMC were cultured with S. aureus 161:2 cell-free supernatants (CFS), staphylococcal enterotoxin A or CD3/CD28-beads alone, or in combination with Lactobacillus rhamnosus GG-CFS or Lactobacillus reuteri DSM 17938-CFS and activation of T and NK cells was evaluated. S. aureus-CFS induced IFN-γ and CD107a expression as well as proliferation. Costimulation with lacto-bacilli-CFS dampened lymphocyte-activation in all cell types analyzed. Preincubation with lactobacilli-CFS was enough to reduce subsequent activation, and the absence of APC or APC-derived IL-10 did not prevent lactobacilli-mediated dampening. Finally, lactate selectively dampened activation of unconventional T cells and NK cells. In summary, we show that molecules present in the lactobacilli-CFS are able to directly dampen in vitro activation of conventional and unconventional T cells and of NK cells. This study provides novel insights on the immune-modulatory nature of probiotic lactobacilli and suggests a role for lactobacilli in the modulation of induced T and NK cell activation.

Shigella dysenteriae Type 1 dysentery is a major cause of morbidity and mortality in children from less developed and developing countries. The present study explores the hypothesis that lactobacilli protect the host cell during S. dysenteriae Type 1 infection and its mechanism of action.Caco-2 cells incubated for 1 h with Lactobacillus rhamnosus or Lactobacillus acidophilus at the multiplicity of infection of 100, either alone or in combination followed by addition of Shigella at the same multiplicity of infection for 5 h served as treatment groups. Cells incubated with Shigella without lactobacilli addition served as infected cells. At the end of experimental period, cells were processed suitably to enumerate adherent and internalized Shigella. Reverse transcription-polymerase chain reaction was performed to assess mRNA expression of interleukin-8 and tumour necrosis factor-α. Immunoblot for heat shock protein-70 and cytotoxicity assay were performed.Pretreatment with the combination of lactobacilli significantly (p < 0.05) prevented adherence and internalization of Shigella coupled with reduced expression of tumour necrosis factor-α and interleukin-8 in host cells.L. rhamnosus and L. acidophilus, synergistically offered better protection during S. dysenteriae Type 1 infection by efficiently inhibiting adherence and internalization of Shigella coupled with inhibition of pro-inflammatory response.

BACKGROUND: Contemporary purification techniques of Lactobacilli bacteriocins include chemical precipitation and separation through solvents to obtain highly potent semi-purified bacteriocins. These methods are laborious and bacteriocin yields are low. To address this problem a set of new, efficient, cost effective media, was created, containing low molecular weight nutrient sources (LMWM). Using these media future separation and concentration of the desired metabolic products, using ultra-and nano-filtration from the cultured broth was possible. RESULTS: The LMWM were made through serial filtration (filters varying in pore size 30 kDa, 4 kDa and 1 kDa MWCO) of a modified optimum liquid medium for Lactobacilli growth. The developed media were tested for bacteriocin production and biomass growth, using three known bacteriocin-producing Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586. All were successfully grown (µ max 0.16 to 0.18 h −1) on the LMWM and produced a significant amount of bacteriocins in the range 110 to 130 IU mL −1 . CONCLUSIONS: LMWM do support Lactobacilli growth and bacteriocin production, establishing an alternative to the current production nutrient media. The uptake of the nutrient sources is facilitated as nitrogen sources, which were primarily responsible for growth, were supported in less complex forms.