B-Group Vitamins as Potential Prebiotic Candidates: Their Effects on the Human Gut Microbiome

In recent years, thousands of studies have demonstrated the importance of the gut microbiome for human health and its relationship with certain diseases. The search for new gut microbiome modulators has thus become an objective to beneficially alter the gut microbiome composition and/or metabolic activity, which may modify intestinal physiology. Growing evidence has shown that B-group vitamins might be considered as potential candidates as gut microbiome modulators. However, the relationship between the B-group vitamins and the gut microbiome remains largely unexplored. Studies have suggested that non-absorbed B-group vitamins administered orally can reach the distal intestine or even the colon where these vitamins may have potential health benefits for the host. Clinical trials supporting this effect are still limited. In this review, we discuss evidence regarding the modulatory effects of B-group vitamins on the gut microbiome with a focus on their potential role as prebiotic candidates.

Beneficial Effects of Lactobacilli Species on Intestinal Homeostasis in Low-Grade Inflammation and Stress Rodent Models and Their Implication in the Modulation of the Adhesive Junctional Complex

Intestinal barrier integrity is essential in order to maintain the homeostasis of mucosal functions and efficient defensive reactions against chemical and microbial challenges. An impairment of the intestinal barrier has been observed in several chronic diseases. The gut microbiota and its impact on intestinal homeostasis is well described and numerous studies suggest the ability of some probiotic strains to protect the intestinal epithelial integrity and host homeostasis. In this work, we aimed to assess the beneficial effects of three Lactobacillus strains (Lacticaseibacillus rhamnosus LR04, Lacticaseibacillus casei LC03, and Lactiplantibacillus plantarum CNCM I-4459) and their mechanism of action in low-grade inflammation or neonatal maternal separation models in mice. We compared the impact of these strains to that of the well-known probiotic Lacticaseibacillus rhamnosus GG. Our results demonstrated that the three strains have the potential to restore the barrier functions by (i) increasing mucus production, (ii) restoring normal permeability, and (iii) modulating colonic hypersensitivity. Moreover, gene expression analysis of junctional proteins revealed the implication of Claudin 2 and Cingulin in the mechanisms that underlie the interactions between the strains and the host. Taken together, our data suggest that LR04, CNCM I-4459, and LC03 restore the functions of an impaired intestinal barrier.

Use of Probiotic Bacteria and Bacteriocins as an Alternative to Antibiotics in Aquaculture

In addition to their use in human medicine, antimicrobials are also used in food animals and aquaculture, and their use can be categorized as therapeutic against bacterial infections. The use of antimicrobials in aquaculture may involve a broad environmental application that affects a wide variety of bacteria, promoting the spread of bacterial resistance genes. Probiotics and bacteriocins, antimicrobial peptides produced by some types of lactic acid bacteria (LAB), have been successfully tested in aquatic animals as alternatives to control bacterial infections. Supplementation might have beneficial impacts on the intestinal microbiota, immune response, development, and/or weight gain, without the issues associated with antibiotic use. Thus, probiotics and bacteriocins represent feasible alternatives to antibiotics. Here, we provide an update with respect to the relevance of aquaculture in the animal protein production sector, as well as the present and future challenges generated by outbreaks and antimicrobial resistance, while highlighting the potential role of probiotics and bacteriocins to address these challenges. In addition, we conducted data analysis using a simple linear regression model to determine whether a linear relationship exists between probiotic dose added to feed and three variables of interest selected, including specific growth rate, feed conversion ratio, and lysozyme activity.

Use of genetically modified lactic acid bacteria and bifidobacteria as live delivery vectors for human and animal health

There is now strong evidence to support the interest in using lactic acid bacteria (LAB)in particular, strains of lactococci and lactobacilli, as well as bifidobacteria, for the development of new live vectors for human and animal health purposes. LAB are Gram-positive bacteria that have been used for millennia in the production of fermented foods. In addition, numerous studies have shown that genetically modified LAB and bifodobacteria can induce a systemic and mucosal immune response against certain antigens when administered mucosally. They are therefore good candidates for the development of new mucosal delivery strategies and are attractive alternatives to vaccines based on attenuated pathogenic bacteria whose use presents health risks. This article reviews the most recent research and advances in the use of LAB and bifidobacteria as live delivery vectors for human and animal health.

Neuroprotective Effect of Riboflavin Producing Lactic Acid Bacteria in Parkinsonian Models

Oxidative stress and inflammatory processes might contribute to the cascade of events leading Parkinson disease (PD); and vitamins such as riboflavin can exert protection on vulnerable neurons in neurodegenerative conditions. Previously, it was demonstrated that a mixture of lactic acid bacteria (including a riboflavin-producing strain) improved motor skills in a parkinsonian model. The aim of the present work was to investigate the neuroprotective potential of Lactiplantibacillus (L.) plantarum CRL2130, a riboflavin-producing strain in PD models. In vitro, N2a differentiated neurons were exposed the neurotoxin 1-methyl-4-phenylpyridinium (MPP+) and treated with intracellular bacterial extracts or commercial riboflavin. In vivo, adult male C57BL/6 mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and probenecid, and received orally L. plantarum CRL2130, L. plantarum CRL725 (parent strain that produces low levels of riboflavin) or commercial vitamin. Results showed that when N2a cells were incubated with intracellular extract from L. plantarum CRL2130 maintained the viability, and significantly decreased the release of IL-6 and the formation of reactive oxygen species (ROS), all affected by MPP+. In vivo, the administration of L. plantarum CRL2130 attenuated motor deficits and prevented dopaminergic neuronal death. Decrease of pro-inflammatory cytokines and increase of IL-10 in both serum and brain were observed in samples from mice that received L. plantarum CRL2130 compared to MPTP control group (without treatment). In addition, these beneficial effects were similar or improved when compared with animals that received commercial riboflavin. In conclusion, L. plantarum CRL2130 showed a neuroprotective effect in both PD models through anti-oxidant/anti-inflammatory mechanisms.

Neuroprotective effect of thiamine-producing lactic acid bacteria in a murine Parkinsonian model

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by deterioration and loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in motor deficits. Many studies have...

Quinoa sourdough-based biscuits with high antioxidant activity fermented with autochthonous lactic acid bacteria

AIMS

To evaluate the capacity of autochthonous lactic acid bacteria (LAB) (43) from Andean grains to increase the antioxidant activity (AOA) and total phenolic compounds (TPCs) in quinoa sourdough to select best performing strains to be used as starter cultures in the elaboration of biscuits.

METHODS AND RESULTS

Microbial growth (CFU per g) and pH were evaluated during quinoa dough fermentation. Counts were increased in a range of 0.61-2.97 log CFU per g and pH values between 3.95 and 4.54 were determined after 24 h at 30°C of fermentation. Methanolic (ME) and aqueous (AE) extracts were obtained at the end of fermentation, and free radical scavenging capacity was performed by the DPPH and ABTS methods. ME was selected for further analysis using other methods and TPC quantification. Principal component analysis showed the highest scores of growth, acidification capacity, AOA and TPC for the strains Lc. mesenteroides subsp. mesenteroides CRL 2131 and L. plantarum CRL 1964 and CRL 1973. AOA and TPC in biscuits made with sourdough from these LAB were higher than the acidified and uninoculated controls.

CONCLUSIONS

Autochthonous LAB strains (3) increased the AOA of quinoa-based biscuits.

SIGNIFICANCE AND IMPACT OF THE STUDY

Quinoa sourdough obtained with selected LAB is suitable as an ingredient for bakery foods with improved antioxidant status.

Thiamine-producing lactic acid bacteria and their potential use in the prevention of neurodegenerative diseases

Thiamine or vitamin B1, an essential micronutrient mainly involved in energy production, has a beneficial impact on the nervous system, and its deficiency can be associated with the development and progression of neurodegenerative diseases. The aim of this work was to select thiamine-producing lactic acid bacteria (LAB) and study their physiological effects using neuron cell cultures. In this study, 23 LAB able to produce thiamine were identified by growth in thiamine-free synthetic medium. Intra- and extracellular thiamine concentrations were determined using a microbiological method and results confirmed by HPLC techniques. A wide variation in vitamin production was found showing that this property was not only species specific but also a strain-dependent trait. Five of these strains were pre-selected for their capacity to produce higher concentrations of thiamine. Only the pre-treatment with the intracellular extract of Lactiplantibacillus (L.) plantarum CRL 1905 increased significantly neuronal survival in N2a cells' model of neurotoxicity (MPP⁺) with thiamine deficiency conditions (amprolium). Furthermore, amprolium-resistant variants of CRL 1905 were isolated by exposition of the strain to increasing concentrations of this toxic thiamine analogue. The variant A9 was able to increase more than 2 times the intracellular thiamine production of the original strain. A9 bacterial extract significantly prevented neuronal cell death and the increase of IL-6. The amprolium-resistant strain A9 showed a modulating and neuroprotective effect in an in vitro model of neurotoxicity constituting a potential bio-strategy to counteract thiamine deficiencies and thus prevent or treat neurodegenerative diseases. KEY POINTS: • LAB can produce thiamine in a species- and strain-dependant manner. • L. plantarum CRL 1905 significantly reduce MPP⁺-induced neurotoxicity in N2a cells. • Amprolium-resistant strain A9 has neuroprotective effect and prevents IL-6 increase.

Evaluation of vitamin-producing and immunomodulatory lactic acid bacteria as a potential co-adjuvant for cancer therapy in a mouse model

AIMS

To evaluate a mixture of selected lactic acid bacteria (LAB) (a riboflavin-producer, a folate-producer and an immunomodulatory strain) as co-adjuvant for 5-fluorouracil (5-FU) chemotherapy in cell culture and using a 4T1 cell animal model of breast cancer.

METHODS AND RESULTS

The viability of Caco-2 cells exposed to 5-FU and/or LAB was analysed. Mice bearing breast tumour were treated with 5-FU and/or LAB. Tumour growth was measured. Intestinal mucositis (IM) was evaluated in small intestine; haematological parameters and plasma cytokines were determined. The bacterial mixture did not negatively affect the cytotoxic activity of 5-FU on Caco-2 cells. The LAB mixture attenuated the IM and prevented blood cell decreases associated with 5-FU treatment. Mice that received 5-FU and LAB mixture decreased tumour growth and showed modulation of systemic cytokines modified by both tumour growth and 5-FU treatment. The LAB mixture by itself delayed tumour growth.

CONCLUSIONS

The mixture of selected LAB was able to reduce the side-effects associated with chemotherapy without affecting its primary anti-tumour activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

This bacterial mixture could prevent the interruption of conventional oncologic therapies by reducing undesirable side-effects. In addition, this blend would provide essential nutrients (vitamins) to oncology patients.

Retraction Note to: Lactobacillus casei BL23 regulates Treg and Th17 T-cell populations and reduces DMH-associated colorectal cancer

This article has been retracted. Please see the retraction notice for more detail: https://doi.org/10.1007/s00535-015-1158-9 .

The Ability of Riboflavin-Overproducing Lactiplantibacillus plantarum Strains to Survive Under Gastrointestinal Conditions

Riboflavin, vitamin B2, is essential for humans and has to be obtained from the diet. Some lactic acid bacteria (LAB) produce this vitamin, and they can be used for in-situ fortification of foods. This could be an alternative to supplementation with chemically synthesized vitamin, to palliate riboflavin deficiencies in specific groups of people. Moreover, if the producing LAB could survive in the gastrointestinal stress (GIT) they could be added as probiotics in this environment. In the present study we tested two riboflavin-overproducing Lactiplantibacillus plantarum strains (M5MA1-B2 and M9MG6-B2), spontaneous mutants of LAB isolated from chicha, a traditional Andean beverage. These two LAB, and also their isogenic strains M5MA1-B2[pRCR12] and M9MG6-B2[pRCR12], expressing the mCherry protein from the pRCR12 plasmid, were evaluated in vitro under simulated GIT conditions. Among other, specifically developed protein fluorescence assays were used. The four LAB showed similar levels of adhesion (>6.0%) to Caco-2 cells, higher than that of the probiotic Lacticaseibacillus rhamnosus GG strain (4.51%). Thus, LAB biofilm formation was assessed in the labeled cells by intracellular mCherry fluorescence and in the unlabeled parental strains by crystal violet staining. Both methods detected the formation of consistent biofilms by the L. plantarum strains. The quantification of mCherry fluorescence was also used to analyze LAB auto-aggregation properties. High levels of auto-aggregation were detected for both M5MA1-B2[pRCR12] and M9MG6-B2[pRCR12]. Survival of LAB included in a commercial cereal-based food matrix (Incaparina) under GIT conditions was also evaluated. The four LAB were resistant in vitro to the stomach and intestinal stresses, and proliferated in this environment, indicating a protective and nutritional effect of the Incaparina on the bacteria. Also, M9MG6-B2 survival in the presence or absence of Incaparina was evaluated in vivo in a BALB/c mouse model. The administration of the M9MG6-B2 strain alone or together with Incaparina had no adverse effect on the health, growth and/or well-being of the rodents. In addition, an increment in the villus length/crypt depth ratio was observed. The overall results obtained indicate that the LAB studied have probiotic characteristics of interest for the development of functional foods.

Recent update on lactic acid bacteria producing riboflavin and folates: application for food fortification and treatment of intestinal inflammation

Lactic acid bacteria (LAB), widely used as starter cultures for the fermentation of a large variety of food, can improve the safety, shelf life, nutritional value and overall quality of the fermented products. In this regard, the selection of strains delivering health-promoting compounds is now the main objective of many researchers. Although most LAB are auxotrophic for several vitamins, it is known that certain strains have the capability to synthesize B-group vitamins. This is an important property since humans cannot synthesize most vitamins, and these could be obtained by consuming LAB fermented foods. This review discusses the use of LAB as an alternative to fortification by the chemical synthesis to increase riboflavin and folate concentrations in food. Moreover, it provides an overview of the recent applications of vitamin-producing LAB with anti-inflammatory/antioxidant activities against gastrointestinal tract inflammation. This review shows the potential uses of riboflavin and folates producing LAB for the biofortification of food, as therapeutics against intestinal pathologies and to complement anti-inflammatory/anti-neoplastic treatments.

Effect of processing on polyphenol profile, aflatoxin concentration and allergenicity of peanuts

Worldwide peanuts are often thermally processed before consumption, which might alter its bioactive composition and toxicity. The presented work explores the effect of processing methods such as roasting, frying, and pressure cooking on the bioactive composition, polyphenol profiles, aflatoxin concentration and, allergenicity response of peanuts. Effect of processing methods was assessed by monitoring total polyphenol content (TPC), total flavonoid content (TFC), antioxidant activity by DPPH & ABTS radicals, sensory analysis and, indirect ELISA. Compared to raw peanuts, all processing methods caused significant differences in TPC, TFC, DPPH & ABTS radical scavenging activities. Comparison of polyphenol profiles of raw to processed peanuts by LC-ESI-Q-TOF-MS chromatograms revealed different effects on concentrations of individual bioactive polyphenols. Indirect ELISA showed a significant decrease in the assay response on pressure cooking as compared to other samples. Total aflatoxin concentration was significantly reduced after processing in roasted (97.7%) and fried (98.3%) peanuts. Optimum processing conditions based on bioactive concentration and sensory analysis were found to be, roasting: 150 °C for 10 min, frying: 170 °C for 2 min and, pressure cooking: 15 min. Polyphenol profiles and bioactive constituents of peanuts were influenced by processing and may alter health benefits associated with them hence, vital for research and food industry applications.

Bioprospecting of probiotics with antimicrobial activities against Salmonella Heidelberg and that produce B-complex vitamins as potential supplements in poultry nutrition

The demand for animal protein for human consumption has been risen exponentially. Modern animal production practices are associated with the regular use of antibiotics, potentially increasing the emerging multi-resistant bacteria, which may have a negative impact on public health. In poultry production, substances capable of maximizing the animals’ performance and displaying an antimicrobial activity against pathogens are very well desirable features. Probiotic can be an efficient solution for such a task. In the present work, lactic acid bacteria (LAB) were isolated from chicken cecum and screened for their antagonistic effect towards many pathogens. Their capacity of producing the B-complex vitamins folate and riboflavin were also evaluated. From 314 isolates, three (C43, C175 and C195) produced Bacteriocin-Like Inhibitory Substances (BLIS) against Staphylococcus aureus (inhibition zones of 18.9, 21.5, 19.5 mm, respectively) and also inhibited the growth of Salmonella Heidelberg. The isolate C43 was identified as Enterococcus faecium, while C173 and C195 were both identified as Lactococcus lactis subsp. lactis. Moreover, the isolates L. lactis subsp. lactis strains C173 and C195 demonstrated high potential to be used as probiotic in poultry feed, in addition to their advantage of producing folate (58.0 and 595.5 ng/mL, respectively) and riboflavin (223.3 and 175.0 ng/mL, respectively).

Quinoa pasta fermented with lactic acid bacteria prevents nutritional deficiencies in mice

In recent years, quinoa (Chenopodium quinoa Willd), an ancestral crop of the Andean region of South America, has gained worldwide attention due to its high nutritional value. This grain is a good source of several vitamins and minerals; however, their bioavailability is decreased by the presence of antinutritional factors such as phytic acid. These compounds can be reduced using lactic acid bacteria (LAB), that have a GRAS (Generally Recognized as Safe) status and have traditionally been associated with food fermentation due to their biosynthetic capacity and metabolic versatility. The objective of this study was to evaluate the effectiveness of a pasta made with quinoa sourdough fermented by L. plantarum strains producing vitamins B₂ and B₉ and phytase to prevent vitamins and minerals deficiency using an in vivo mouse model. The results showed that the pasta fermented with the mixed culture containing L. plantarum CRL 2107 + L. plantarum CRL 1964 present increased B₂ and B₉ levels in mice blood. Likewise, higher concentrations of P, Ca⁺², Fe⁺², Mg⁺² (18.75, 10.70, 0.37, 4.85 mg/dL, respectively) were determined with respect to the deficient group (DG) (9.85, 9.90, 0.26, 3.34 mg/dL, respectively). Hematological studies showed an increase in hemoglobin (14.4 ± 0.6 g/dL), and hematocrit (Htc, 47.0 ± 0.6%) values, compared to the DG (Hb: 12.6 ± 0.5 g/dL, Hto: 39.9 ± 1.1%). Furthermore, histological evaluations of the intestines showed an increase of the small intestine villi length in this latter group. The results allow us to conclude that bio-enrichment of quinoa pasta using LAB could be a novel strategy to increase vitamin and minerals bioavailability in cereal/pseudocereal - derived foods.

Beneficial effect of a mixture of vitamin-producing and immune-modulating lactic acid bacteria as adjuvant for therapy in a recurrent mouse colitis model

Inflammatory bowel diseases are chronic and relapsing-remitting disorders that affect the gastrointestinal tract. Previously, the administration of folate and riboflavin-producing lactic acid bacteria (LAB) or an immune-modulating strain showed beneficial effects as they were able to reduce the acute inflammation in mouse models. The aim of this work was to evaluate a mixture of vitamin-producing and immune-modulating LAB administering together with an anti-inflammatory drug during the remission period of a mouse model of recurrent colitis. BALB/c mice were intrarectally instilled with trinitrobenzene sulfonic acid (TNBS) and those who recovered from this acute challenge were given the LAB mixture, mesalazine, or the combination of both (mesalazine + LAB) during 21 days, followed by a second challenge with TNBS. Control mice instilled with ethanol (vehicle of TNBS) and receiving the different treatments were also evaluated in order to study the effect of chronic anti-inflammatory therapy. The combination of mesalazine and LAB mixture was the most effective to decrease the intestinal damage at macroscopic and histological levels and to reduce pro-inflammatory cytokines (IL-6 and TNF-α) in intestinal fluids. In animals instilled with ethanol, mesalazine produced a loss of body weight and intestinal damages with increased IL-6. These side effects were prevented by the co-administration of mesalazine and the LAB mixture. The LAB blend did not affect the primary anti-inflammatory treatment, was able to improve it, and also prevented the side effects of this therapy.

Real-Time Detection of Riboflavin Production by Lactobacillus plantarum Strains and Tracking of Their Gastrointestinal Survival and Functionality in vitro and in vivo Using mCherry Labeling

Some strains of lactic acid bacteria (LAB) produce riboflavin, a water-soluble vitamin of the B complex, essential for human beings. Here, we have evaluated riboflavin (B2 vitamin) production by five Lactobacillus plantarum strains isolated from chicha, a traditional maize-based fermented alcoholic beverage from north-western Argentina and their isogenic riboflavin-overproducing derivatives previously selected using roseoflavin. A direct fluorescence spectroscopic detection method to quantify riboflavin production in bacterial culture supernatants has been tested. Comparison of the efficiency for riboflavin fluorescence quantification with and without prior HPLC fractionation showed that the developed method is a rapid and easy test for selection of B2 vitamin-producing strains. In addition, it can be used for quantitative detection of the vitamin production in real time during bacterial growth. On the basis of this and previous analyses, the L. plantarum M5MA1-B2 riboflavin overproducer was selected for in vitro and in vivo studies after being fluorescently labeled by transfer of the pRCR12 plasmid, which encodes the mCherry protein. The labeling did not affect negatively the growth, the riboflavin production nor the adhesion of the strain to Caco-2 cells. Thus, L. plantarum M5MA1-B2[pRCR12] was evaluated for its survival under digestive tract stresses in the presence of microbiota in the dynamic multistage BFBL gut model and in a murine model. After exposure to both models, M5MA1-B2[pRCR12] could be recovered and detected by the pink color of the colonies. The results indicated a satisfactory resistance of the strain to gastric and intestinal stress conditions but a low colonization capability observed both in vitro and in vivo. Overall, L. plantarum M5MA1-B2 could be proposed as a probiotic strain for the development of functional foods.

Influence of passion fruit by-product and fructooligosaccharides on the viability of Streptococcus thermophilus TH-4 and Lactobacillus rhamnosus LGG in folate bio-enriched fermented soy products and their effect on probiotic survival and folate bio-accessibility under in vitro simulated gastrointestinal conditions

This study aimed to evaluate the influence of passion fruit by-product (PFBP) and fructooligosaccharides (FOS) on the viability of Streptococcus thermophilus TH-4 and Lactobacillus rhamnosus LGG in folate bio-enriched fermented soy products and their effect on probiotic survival and folate bio-accessibility under in vitro simulated gastrointestinal conditions during storage of the products at 4 °C for up to 28 days (at days 1, 14, and 28). Kinetic parameters and folate contents before and after fermentation were also evaluated. Four different bio-enriched soy products in which the two microorganisms were used in co-cultures were studied and PFBP and/or FOS were added at 1 g/100 g, except for the control product. No differences (p < 0.05) between the fermented soy products (FSP) were observed for the maximum acidification rate (Vmax) and the time to reach the Vmax (Tmax) or pH 5.5 (Tf), indicating that the use of PFBP and/or FOS did not affect the fermentation kinetic parameters. Only Lb. rhamnosus LGG retained the desired viability (>8 log CFU/mL) during storage, whereas St. thermophilus TH-4 populations decreased by day 14 reaching counts between 6.4 and 5.5 log CFU/mL by day 28. The folate content of all FSP increased after fermentation and the simultaneous presence of PFBP and FOS stimulated the co-culture to increase folate production. Folate content in all FSP decreased during storage. Lb. rhamnosus LGG was recovered at the end of the simulated digestion, but PFBP and/or FOS did not affect recovery. The folate content increased during the gastrointestinal assay for all FSP, especially for FSP without supplementation, suggesting an in vitro increase of folate bio-accessibility. Therefore, the bio-enriched probiotic FSP presented a great potential as an innovative functional food by delivering probiotic microorganisms and providing 14% of the recommended daily folate intake. The folate content of the FSP might be increased during gastrointestinal stress conditions, which could contribute to increase the folate bio-accessibility in the gut.

Vitamin Producing Lactic Acid Bacteria as Complementary Treatments for Intestinal Inflammation

BACKGROUND

Current therapies for against inflammatory bowel disease (IBD) are sometimes limited by high costs, high toxicities and/or undesirable side effects, reasons for which new treatments are constantly being developed and studied. In this regards, an increasing mass of data has demonstrated that fecal transplantations and probiotic supplementations have shown promising effects and could be considered as adjunct IBD treatments to decrease some of the unwanted side effects caused by primary treatments. Furthermore, there is also mounting evidence that suggests that certain vitamins could provide antiinflammatory effects and it has been shown that certain strains of lactic acid bacteria (LAB), the most commonly used probiotic microorganisms, can produce biologically active forms of certain vitamins.

OBJECTIVE

To discuss the potential role of the vitamin-producing LAB on intestinal inflammatory diseases.

METHOD

A thorough search of bibliographic databases for peer-reviewed research on the effect of vitamins produced by LAB on inflammatory processes was performed.

RESULTS

There is mounting research that vitamin producing LAB could provide antiinflammatory effects.

CONCLUSION

The potential role of vitamin producing LAB was discussed not only because they could be used to decrease inflammation but also because they could provide the host with essential nutrients that are normally deficient in IBD patients due to altered intestinal morphologies.

Protective effect of the riboflavin-overproducing strain Lactobacillus plantarum CRL2130 on intestinal mucositis in mice

OBJECTIVES

Intestinal mucositis (IM) is a local inflammatory response that causes alterations of the intestinal structure that in turn affect nutrient absorption and a side effect that is commonly associated with cancer treatments. Lactobacillus plantarum CRL2130 is a riboflavin-overproducing strain that has previously been shown to provide antiinflammatory properties. The objective of this study was to evaluate the effects of this riboflavin-producing strain in a chemically induced murine mucositis model.

METHODS

Mucositis was induced by daily injections of 5-fluororacil (5-FU) after which mice were either given L. plantarum CRL2130, CRL725 (strain from which CRL2130 was derived that does not overproduce riboflavin), or commercial riboflavin twice daily during 6 d of chemotherapy agent injections. The effect of the strains and riboflavin was also evaluated in vitro using Caco-2 intestinal cancer cell cultures to determine if they interfere with 5-FU's anticancer activity.

RESULTS

The administration of L. plantarum CRL2130 significantly attenuated the pathologic changes induced by 5-FU in mice such as body weight loss, diarrhea, shortening of villus height, increases in proinflammatory cytokine concentrations, and elevated production of interleukin 10. In vitro assays using Caco-2 cells showed that the effectiveness of 5-FU was not affected by L. plantarum CRL2130 and that this strain exerted an inhibitory mechanism against oxidative stress.

CONCLUSIONS

These results indicate that the riboflavin-overproducing strain L. plantarum CRL2130 could be useful to prevent mucositis during cancer treatments and would not affect the primary treatment.

Effect of riboflavin-producing bacteria against chemically induced colitis in mice

AIM

To assess the anti-inflammatory effect associated with individual probiotic suspensions of riboflavin-producing lactic acid bacteria (LAB) in a colitis murine model.

METHODS AND RESULTS

Mice intrarectally inoculated with trinitrobenzene sulfonic acid (TNBS) were orally administered with individual suspensions of riboflavin-producing strains: Lactobacillus (Lact.) plantarum CRL2130, Lact. paracasei CRL76, Lact. bulgaricus CRL871 and Streptococcus thermophilus CRL803; and a nonriboflavin-producing strain or commercial riboflavin. The extent of colonic damage and inflammation and microbial translocation to liver were evaluated. iNOs enzyme was analysed in the intestinal tissues and cytokine concentrations in the intestinal fluids. Animals given either one of the four riboflavin-producing strains showed lower macroscopic and histologic damage scores, lower microbial translocation to liver, significant decreases of iNOs+ cells in their large intestines and decreased proinflammatory cytokines, compared with mice without treatment. The administration of pure riboflavin showed similar benefits. Lact. paracasei CRL76 accompanied its anti-inflammatory effect with increased IL-10 levels demonstrating other beneficial properties in addition to the vitamin production.

CONCLUSION

Administration of riboflavin-producing strains prevented the intestinal damage induced by TNBS in mice.

SIGNIFICANCE AND IMPACT OF THE STUDY

Riboflavin-producing phenotype in LAB represents a potent tool to select them for preventing/treating IBD.

Lactic Acid Bacteria from Andean Grain Amaranth: A Source of Vitamins and Functional Value Enzymes

Amaranth is a rediscovered pseudocereal with high nutritional properties. Lactic acid fermentation can increase the functional and nutritional value of foods. The aims of this study were to isolate and evaluate the functionality of lactic acid bacteria (LAB) from amaranth. LAB strains (<i>n</i> = 29) isolated from amaranth sourdough and grains included <i>Lactobacillus</i> (<i>L.</i>) <i>plantarum</i> (<i>n</i> = 8), <i>L. rhamnosus</i> (<i>n</i> = 6), <i>Enterococcus</i> (<i>E.</i>) <i>mundtii</i> (<i>n</i> = 4), <i>E. hermanniensis</i> (<i>n</i> = 3), <i>E. durans</i> (<i>n</i> = 1), <i>Enterococcus</i> sp. (<i>n</i> = 1), <i>Leuconostoc</i> (<i>Lc.</i>) <i>mesenteroides</i> (<i>n</i> = 3), and <i>Lc. mesenteroides </i>subsp<i>. mesenteroides </i>(<i>n</i> = 3). Only 21% of the strains showed the ability to synthesize capsular exopolysaccharides or display ropiness and only 8 strains showed amylolytic activity. <i>L. plantarum </i>CRL 2106 and <i>E. durans </i>CRL 2122 showed the highest phytase activity, which is of importance for mineral bioavailability. <i>L. plantarum </i>CRL 2106 and CRL 2107 and <i>Lc. mesenteroides </i>subsp.<i> mesenteroides</i> CRL 2131 synthesized the highest concentrations of B₂ and B₉ vitamin (140-250 ng/mL). This study demonstrates the potential of LAB to improve the nutritional and functional values of pseudocereal-derived foods.

Beneficial effects on host energy metabolism of short-chain fatty acids and vitamins produced by commensal and probiotic bacteria

The aim of this review is to summarize the effect in host energy metabolism of the production of B group vitamins and short chain fatty acids (SCFA) by commensal, food-grade and probiotic bacteria, which are also actors of the mammalian nutrition. The mechanisms of how these microbial end products, produced by these bacterial strains, act on energy metabolism will be discussed. We will show that these vitamins and SCFA producing bacteria could be used as tools to recover energy intakes by either optimizing ATP production from foods or by the fermentation of certain fibers in the gastrointestinal tract (GIT). Original data are also presented in this work where SCFA (acetate, butyrate and propionate) and B group vitamins (riboflavin, folate and thiamine) production was determined for selected probiotic bacteria.

Factors stimulating riboflavin produced by Lactobacillus plantarum CRL 725 grown in a semi-defined medium

Riboflavin (vitamin B₂ ) is one of the B-group water-soluble vitamins and is essential for energy metabolism of the cell. The aim of this study was to determine factors that affect riboflavin production by Lactobacillus (L.) plantarum CRL 725 grown in a semi defined medium and evaluate the expression of its rib genes. The factors found to enhance riboflavin production in this medium were incubation at 30 °C, and the addition of specific medium constituents, such as casamino acids (10 g L^-1 ), guanosine (0.04 g L^-1 ), and sucrose as carbon source (20 g L^-1 ). In these conditions, higher riboflavin concentrations were directly associated with significant increases in the expression of ribA, ribB, and ribC genes. The culture conditions defined in this work and its application to a roseoflavin resistant mutant of L. plantarum allowed for a sixfold increase in riboflavin concentrations in our semi-defined medium which were also significantly higher than those obtained previously using the same strain to ferment soymilk. These conditions should thus be evaluated to increase vitamin production in fermented foods.

Anti-cancer effect of lactic acid bacteria expressing antioxidant enzymes or IL-10 in a colorectal cancer mouse model

The association between inflammatory bowel diseases and colorectal cancer is well documented. The genetic modification of lactic acid bacteria as a tool to increase the anti-inflammatory potential of these microorganisms has also been demonstrated. Thus the aim of the present work was to evaluate the anti-cancer potential of different genetically modified lactic acid bacteria (GM-LAB) producing antioxidant enzymes (catalase or superoxide dismutase) or the anti-inflammatory cytokine IL-10 (protein or DNA delivery) using a chemical induced colon cancer murine model. Dimethilhydrazine was used to induce colorectal cancer in mice. The animals received GM-LAB producing anti-oxidant enzymes, IL-10 or a mixture of different GM-LAB. Intestinal damage, enzyme activities and cytokines were evaluated and compared to the results obtained from mice that received the wild type strains from which derived the GM-LAB. All the GM-LAB assayed showed beneficial effects against colon cancer even though they exerted different mechanisms of action. The importance to select LAB with innate beneficial properties as the progenitor strain was demonstrated with the GM-LAB producing anti-oxidant enzymes. In addition, the best effects for the mixtures GM-LAB that combine different anti-inflammatory mechanism. Results indicate that mixtures of selected LAB and GM-LAB could be used as an adjunct treatment to decrease the inflammatory harmful environment associated to colorectal cancer, especially for patients with chronic intestinal inflammation who have an increased risk to develop colorectal cancer.

Evaluation of the effect of soymilk fermented by a riboflavin-producing Lactobacillus plantarum strain in a murine model of colitis

Inflammatory bowel diseases (IBD) are idiopathic diseases of the gastrointestinal tract characterised by recurrent inflammation that require lifelong treatments. It has been shown that certain strains of lactic acid bacteria (LAB) can produce specific health-promoting compounds in foods or in the gastrointestinal tract that can in turn prevent and/or treat IBD. This study was designed to evaluate the possible therapeutic potential of soymilk fermented by the riboflavin-producing strain Lactobacillus plantarum CRL 2130 in a trinitrobenzene sulfonic induced colitis mouse model. Mice that received soymilk fermented by L. plantarum CRL 2130 showed a decrease in weight loss, lower damage scores in their large intestines, lower microbial translocation to liver and decreased cytokines levels in their intestinal fluids compared to animals that received unfermented soymilk or soymilk fermented by a non-riboflavin-producing L. plantarum strain. This is the first report that demonstrates that a riboflavin-producing LAB was able to prevent experimental colitis in a murine model.

Supplementation with fruit and okara soybean by-products and amaranth flour increases the folate production by starter and probiotic cultures

The ability of two starter cultures (Streptococcus (S.) thermophilus ST-M6 and St. thermophilus TA-40) and eleven probiotic cultures (St. thermophilus TH-4, Lactobacillus (Lb.) acidophilus LA-5, Lb. fermentum PCC, Lb. reuteri RC-14, Lb. paracasei subsp. paracasei, Lb. casei 431, Lb. paracasei subsp. paracasei F19, Lb. rhamnosus GR-1, and Lb. rhamnosus LGG, Bifidobacterium (B.) animalis subsp. lactis BB-12, B. longum subsp. longum BB-46, and B. longum subsp. infantis BB-02) to produce folate in a modified MRS broth (mMRS) supplemented with different fruit (passion fruit, acerola, orange, and mango) and okara soybean by-products and amaranth flour was investigated. Initially, the folate content of each vegetable substrate was determined: passion fruit by-product showed the lowest folate content (8±2ng/mL) and okara the highest (457±22ng/mL). When the orange by-product and amaranth flour were added to mMRS, all strains were able to increase folate production after 24h of fermentation. B. longum subsp infantis BB-02 produced the highest concentrations (1223±116ng/mL) in amaranth flour. Okara was the substrate that had the lowest impact on the folate production by all strains evaluated. Lb. acidophilus LA-5 (297±36ng/mL) and B. animalis subsp. lactis BB-12 (237±23ng/mL) were also able to produce folate after growth in mMRS containing acerola and orange by-products, respectively. The results of this study demonstrate that folate production is not only strain-dependent but also influenced by the addition of different substrates in the growth media.

Ancestral Andean grain quinoa as source of lactic acid bacteria capable to degrade phytate and produce B-group vitamins

The lactic acid bacteria (LAB) microbiota of quinoa grains (QG) and spontaneous sourdough (QSS) was evaluated. Different strains of Lactobacillus (L.) plantarum (7), L. rhamnosus (5), L. sakei (1), Pediococcus (Ped.) pentosaceus (9), Leuconostoc (Leuc.) mesenteroides (1), Enterococcus (E.) casseliflavus (2), E. mundtii (3), E. hirae (1), E. gallinarum (12), Enterococcus sp. (1), and E. hermanniensis (2) were isolated, identified and characterized. Only four strains isolated from QSS and eight strains isolated from QG showed amylolytic activity. L. plantarum CRL 1973 and CRL 1970, L. rhamnosus CRL 1972 and L. sakei CRL 1978 produced elevated concentrations of folate with strain CRL 1973 producing the highest concentration (143±6ng/ml). L. rhamnosus, isolated from QSS, was the LAB species that produced the most elevated concentrations of total riboflavin (>270ng/ml) with strain CRL 1963 producing the highest amounts (360±10ng/ml). Phytase activity, evaluated in forty-four LAB strains from quinoa, was predominantly detected in L. rhamnosus and Enterococci strains with the highest activities observed in E. mundtii CRL 2007 (957±25U/ml) followed by E. casseliflavus CRL 1988 (684±38U/ml), Leuc. mesenteroides CRL 2012 (617±38U/ml) and L. rhamnosus CRL 1983 (606±79U/ml). In conclusion, this study shows that a diverse LAB microbiota is present in quinoa with important properties; these microorganisms could be used as potential starter cultures to increase the nutritional and functional properties of Andean grains based foods.

Evaluation of the biosafety of recombinant lactic acid bacteria designed to prevent and treat colitis

Inflammatory bowel diseases (IBDs) affect the gastrointestinal tract and are characterized by recurrent inflammation that requires lifelong therapies. Probiotics such as lactic acid bacteria (LAB) have been proposed to complement current treatment protocols for these patients; however, their characteristics are strain dependent. In this regard, certain novel characteristics are only possible through the genetic modification of these beneficial micro-organisms. Different delivery systems, such as protein delivery of anti-oxidant enzymes and anti-inflammatory cytokines, have been shown to be effective in preventing and treating IBD in animal models. In this study, the safety of the recombinant LAB (recLAB) Streptococcus thermophilus CRL807 : CAT, S. thermophilus CRL807 : SOD, Lactococcus lactis NCDO2118 pXILCYT :  IL-10, L. lactis MG1363 pValac : IL-10 and L. lactis MG1363 pGroESL : IL-10 with proven beneficial effects was compared to their progenitor strains S. thermophilus CRL807, L. lactis NCDO2118 or L. lactis MG1363. The prolonged administration of these genetically modified strains showed that they were just as safe as the native strains from which they derive, as demonstrated by normal animal growth and relative organ weights, absence of microbial translocation from the gastrointestinal tract, normal blood parameters and intestinal histology. The results show the potential use of these recLAB in future therapeutic formulations; however, the use of modern bio-containment systems is required for the future acceptance of these recLAB by the medical community and patients with IBD.

Prospective uses of recombinant Lactococcus lactis expressing both listeriolysin O and mutated internalin A from Listeria monocytogenes as a tool for DNA vaccination

In this study, Lactococcus lactis was engineered to express mutated internalin A on its surface and to secrete large amounts of listeriolysin O (LLO) in order to improve its potential as a vehicle for DNA vaccination. Western blotting experiments demonstrated that the bacterium expressed LLO in both the cytoplasmic and extracellular compartments, with higher quantities found in the culture supernatants. A hemolytic assay showed that the recombinant strain secreted 250 ng active LLO/mg total protein. This mInlA/LLO-producing strain of L. lactis may be used as an alternative tool in DNA vaccination against a number of infectious diseases or in cancer therapy.

Evaluation of a Streptococcus thermophilus strain with innate anti-inflammatory properties as a vehicle for IL-10 cDNA delivery in an acute colitis model

The aim of this work was to develop a Streptococcus (S.) thermophilus strain with improved anti-inflammatory properties due to the incorporation of the therapeutic cDNA delivery plasmid pValac::il-10. To achieve this purpose, cells of S. thermophilus CRL807, previously selected as being an important anti-inflammatory strain, were electroporated with pValac::il-10 plasmid. In order to confirm the functionality of the developed strain, it was co-cultured with human epithelial cells Caco-2 and the production of IL-10 was evaluated by ELISA. Bacterial suspensions of S. thermophilus CRL807 containing pValac::il-10 plasmid or of the wild-type (WT) strain were administered in vivo using a murine model of intestinal inflammation. The animals treated with S. thermophilus CRL807 pValac::il-10 showed a lower body weight loss, microbial translocation to liver and damage scores in their intestines at macroscopical and microscopic levels. Furthermore, a significant increase was observed in the concentration of IL-10 in the intestinal contents of these mice compared to the rest of the experimental groups, accompanied by decreased levels of pro-inflammatory cytokines. The insertion of the therapeutic pValac::il-10 plasmid increased the intrinsic anti-inflammatory activity (synergetic effect) of S. thermophilus CRL807 which could be included in novel treatment protocols for inflammatory bowel diseases.

Relationships between the genome and some phenotypical properties of Lactobacillus fermentum CECT 5716, a probiotic strain isolated from human milk

Lactobacillus fermentum CECT 5716, isolated from human milk, has immunomodulatory, anti-inflammatory, and anti-infectious properties, as revealed by several in vitro and in vivo assays, which suggests a strong potential as a probiotic strain. In this work, some phenotypic properties of L. fermentum CECT 5716 were evaluated, and the genetic basis for the obtained results was searched for in the strain genome. L. fermentum CECT 5716 does not contain plasmids and showed neither bacteriocin nor biogenic amine biosynthesis ability but was able to produce organic acids, glutathione, riboflavin, and folates and to moderately stimulate the maturation of mouse dendritic cells. No prophages could be induced, and the strain was sensitive to all antibiotics proposed by European Food Safety Authority (EFSA) standards, while no transmissible genes potentially involved in antibiotic resistance were detected in its genome. Globally, there was an agreement between the phenotype properties of L. fermentum CECT 5716 and the genetic information contained in its genome.

Effect of probiotic administration on the intestinal microbiota, current knowledge and potential applications

Although it is now known that the human body is colonized by a wide variety of microbial populations in different parts (such as the mouth, pharynx and respiratory system, the skin, the gastro- and urogenital tracts), many effects of the complex interactions between the human host and microbial symbionts are still not completely understood. The dysbiosis of the gastrointestinal tract microbiota is considered to be one of the most important contributing factors in the development of many gastrointestinal diseases such as inflammatory bowel disease, irritable bowel syndrome and colorectal cancer, as well as systemic diseases like obesity, diabetes, atherosclerosis and non-alcoholic fatty liver disease. Fecal microbial transplantations appear to be promising therapies for dysbiosis-associated diseases; however, probiotic microorganisms have been growing in popularity due to increasing numbers of studies proving that certain strains present health promoting properties, among them the beneficial balance of the intestinal microbiota. Inflammatory bowel diseases and obesity are the pathologies in which there are more studies showing this beneficial association using animal models and even in human clinical trials. In this review, the association of the human gut microbiota and human health will be discussed along with the benefits that probiotics can confer on this symbiotic activity and on the prevention or treatment of associated diseases.

Anti-inflammatory effects of Lactococcus lactis NCDO 2118 during the remission period of chemically induced colitis

Background

Many probiotic bacteria have been described as promising tools for the treatment and prevention of inflammatory bowel diseases (IBDs). Most of these bacteria are lactic acid bacteria, which are part of the healthy human microbiota. However, little is known about the effects of transient bacteria present in normal diets, including Lactococcus lactis.

Methods

In the present study, we analysed the immunomodulatory effects of three L. lactis strains in vitro using intestinal epithelial cells. L. lactis NCDO 2118 was administered for 4 days to C57BL/6 mice during the remission period of colitis induced by dextran sodium sulphate (DSS).

Results

Only one strain, L. lactis NCDO 2118, was able to reduce IL-1β-induced IL-8 secretion in Caco-2 cells, suggesting a potential anti-inflammatory effect. Oral treatment using L. lactis NCDO 2118 resulted in a milder form of recurrent colitis than that observed in control diseased mice. This protective effect was not attributable to changes in secretory IgA (sIgA); however, NCDO 2118 administration was associated with an early increase in IL-6 production and sustained IL-10 production in colonic tissue. Mice fed L. lactis NCDO 2118 had an increased number of regulatory CD4⁺ T cells (Tregs) bearing surface TGF-β in its latent form (Latency-associated peptide-LAP) in the mesenteric lymph nodes and spleen.

Conclusions

Here, we identified a new probiotic strain with a potential role in the treatment of IBD, and we elucidated some of the mechanisms underlying its anti-inflammatory effect.

Recombinant Lactococcus lactis fails to secrete bovine chymosine

Bovine chymosin is an important milk-clotting agent used in the manufacturing of cheeses. Currently, the production of recombinant proteins by genetically modified organisms is widespread, leading to greatly reduced costs. Lactococcus (L.) lactis, the model lactic acid bacterium, was considered a good candidate for heterologous chymosin production for the following reasons: (1) it is considered to be a GRAS (generally regarded as safe) microorganism, (2) only one protease is present on its surface, (3) it can secrete proteins of different sizes, and (4) it allows for the direct production of protein in fermented food products. Thus, three genetically modified L. lactis strains were constructed to produce and target the three different forms of bovine chymosin, prochymosin B, chymosin A and chymosin B to the extracellular medium. Although all three proteins were stably produced in L. lactis, none of the forms were detected in the extracellular medium or showed clotting activity in milk. Our hypothesis is that this secretion deficiency and lack of clotting activity can be explained by the recombinant protein being attached to the cell envelope. Thus, the development of other strategies is necessary to achieve both production and targeting of chymosin in L. lactis, which could facilitate the downstream processing and recovery of this industrially important protein.

Mucosal targeting of therapeutic molecules using genetically modified lactic acid bacteria: an update

Lactic acid bacteria (LAB) represent a heterogeneous group of microorganisms naturally present in many foods and those have proved to be effective mucosal delivery vectors. Moreover, some specific strains of LAB exert beneficial properties (known as probiotic effect) on both human and animal health. Although probiotic effects are strain-specific traits, it is theoretically possible, using genetic engineering techniques, to design strains that can exert a variety of beneficial properties. During the two past decades, a large variety of therapeutic molecules has been successfully expressed in LAB, and although this field has been largely reviewed in recent years, approximately 20 new publications appear each year. Thus, the aim of this minireview is not to extensively assess the entire literature but to update progress made within the last 2 years regarding the use of the model LAB Lactococcus lactis and certain species of lactobacilli as live recombinant vectors for the development of new safe mucosal vaccines.

Implications of the human microbiome in inflammatory bowel diseases

The study of the human microbiome or community of microorganisms and collection of genomes found in the human body is one of the fastest growing research areas because many diseases are reported to be associated with microbiome imbalance or dysbiosis. With the improvement in novel sequencing techniques, researchers are now generating millions of sequences of different sites from the human body and evaluating specific differences in microbial communities. The importance of microbiome constituency is so relevant that several consortia like the Human Microbiome project (HMP) and Metagenomics of the Human Intestinal Tract (MetaHIT) project are focusing mainly on the human microbiome. The aim of this review is to highlight points of research in this field, mainly focusing on particular factors that modulate the microbiome and important insights into its potential impact on our health and well-being.

Biochemical, antimicrobial and molecular characterization of a noncytotoxic bacteriocin produced by Lactobacillus plantarum ST71KS

Lactobacillus (Lb.) plantarum ST71KS was isolated from homemade goat feta cheese and identified using biochemical and molecular biology techniques. As shown by Tricine-SDS-PAGE, this lactic acid bacterium produces a bacteriocin (ST71KS) with an estimated molecular weight of 5.0 kDa. Bacteriocin ST71KS was not affected by the presence of α-amylase, catalase and remained stable in a wide range of pH and after treatment with Triton X-100, Triton X-114, Tween 20, Tween 80, NaCl, SDS, urea and EDTA. This bacteriocin also remained active after being heated at 100 °C for 2 h and even after 20 min at 121 °C; however, it was inactivated by proteolitic enzymes. Production of bacteriocin ST71KS reached 6400 AU/mL during stationary growth phase of Lb. plantarum cultivated in MRS at 30 °C and 37 °C. Bacteriocin ST71KS displayed a bactericidal effect against Listeria monocytogenes strains 603 and 607 and did not adsorb to the producer cells. Lb. plantarum ST71KS harbors two bacteriocin genes with homology to plantaricin S and pediocin PA-1. These characteristics indicate that bacteriocin ST71KS is a class IIa bacteriocin. The peptide presented no toxic effect when tested in vitro with kidney Vero cells, indicating safe technological application to control L. monocytogenes in foods.

Bacteria as vitamin suppliers to their host: a gut microbiota perspective

Food-related lactic acid bacteria (LAB) as well as human gut commensals such as bifidobacteria can de novo synthesize and supply vitamins. This is important since humans lack the biosynthetic capacity for most vitamins and these must thus be provided exogenously. Although vitamins are present in a variety of foods, deficiencies still occur, mainly due to malnutrition as a result of insufficient food intake and because of poor eating habits. Fermented milks with high levels of B-group vitamins (such as folate and riboflavin) can be produced by LAB-promoted and possibly bifidobacteria-promoted biosynthesis. Moreover, certain strains of LAB produce the complex vitamin cobalamin (or vitamin B12). In this review, fermented foods with elevated levels of B-group vitamins produced by LAB used as starter cultures will be covered. In addition, genetic abilities for vitamin biosynthesis by selected human gut commensals will be discussed.