Prevalent Human Gut Bacteria Hydrolyse and Metabolise Important Food-Derived Mycotoxins and Masked Mycotoxins

Funding: This study was supported by the Scottish Government Rural and Environment Science and Analytical Services division (RESAS). N.D. was supported by an Elphinstone PhD scholarship from the University of Aberdeen. Acknowledgments: Susan McCormick and Mark Busman at the USDA-Agricultural Research Service in Peoria, IL, USA, are acknowledged for providing the standard solutions of T-2-Glc and HT-2-Glc used in this study. We acknowledge Saima Khalid, who worked with the team when planning this study.Peer reviewedPublisher PD

Mutual Interaction of Phenolic Compounds and Microbiota : Metabolism of Complex Phenolic Apigenin-C- and Kaempferol-O-Derivatives by Human Fecal Samples

PL, FMF, and SHD receive financial support from the Scottish Government Rural and 701 Environment Science and Analytical Services Division (RESAS)Peer reviewedPostprin

Porcine small and large intestinal microbiota rapidly hydrolyze the masked mycotoxin deoxynivalenol-3-glucoside and release deoxynivalenol in spiked batch cultures in vitro

This study was supported by the Scottish Government Rural and Environment Science and Analytical Services division (RESAS) and by the French Agence Nationale de la Recherche (project ANR-13-CESA-0003-03). We thank Anne-Marie Cossalter for her excellent technical assistance with pigs.Peer reviewedPostprin

Chlorogenic acid versus amaranth's caffeoylisocitric acid – Gut microbial degradation of caffeic acid derivatives

PL, FF, and SHD receive financial support from the ScottisMoh Government Rural and Environmental Sciences and Analytical Services (RESAS). Parts of this work were financially supported by the project “Horticultural Innovation and Learning for Improved Nutrition and Livelihood in East Africa” (FZK 031A248J and FKZ 031A248K), funded within the global food security (GlobE) initiative of the German Federal Ministry of Education and Research and the German Federal Ministry of Economic Cooperation and Development.Peer reviewedPostprin

Vitamin biosynthesis by human gut butyrate-producing bacteria and cross-feeding in synthetic microbial communities

ACKNOWLEDGMENTS This project was funded by Danone Nutricia Research. F.M.F., G.H., H.J.F., S.H.D., and P.L. receive support from the Scottish Government Rural and Environment Sciences and Analytical Services. Method development for coculture microbial analysis was partially supported by European 7th Framework grant (289517) “Dietary fibres supporting gut and immune function; from polysaccharide compound to health claim (Fibebiotics).” We thank Timo Kramer for his technical support with the in silico analyses. M.D., J.-M.F., H.J.F., S.H.D., and P.L. conceived and designed the study. E.C.S.-M., I.W., F.M.F., and M.C. acquired data and contributed to interpreting the results. G.H. performed statistical analysis. E.C.S.-M. and P.L. drafted the manuscript. All authors contributed to revising the manuscript and approved the final version.Peer reviewedPublisher PD

Pivotal Roles for pH, Lactate, and Lactate-Utilizing Bacteria in the Stability of a Human Colonic Microbial Ecosystem.

Lactate can be produced by many gut bacteria, but in adults its accumulation in the colon is often an indicator of microbiota perturbation. Using continuous culture anaerobic fermentor systems, we found that lactate concentrations remained low in communities of human colonic bacteria maintained at pH 6.5, even when dl-lactate was infused at 10 or 20 mM. In contrast, lower pH (5.5) led to periodic lactate accumulation following lactate infusion in three fecal microbial communities examined. Lactate accumulation was concomitant with greatly reduced butyrate and propionate production and major shifts in microbiota composition, with Bacteroidetes and anaerobic Firmicutes being replaced by Actinobacteria, lactobacilli, and Proteobacteria Pure-culture experiments confirmed that Bacteroides and Firmicutes isolates were susceptible to growth inhibition by relevant concentrations of lactate and acetate, whereas the lactate-producer Bifidobacterium adolescentis was resistant. To investigate system behavior further, we used a mathematical model (microPop) based on 10 microbial functional groups. By incorporating differential growth inhibition, our model reproduced the chaotic behavior of the system, including the potential for lactate infusion both to promote and to rescue the perturbed system. The modeling revealed that system behavior is critically dependent on the proportion of the community able to convert lactate into butyrate or propionate. Communities with low numbers of lactate-utilizing bacteria are inherently less stable and more prone to lactate-induced perturbations. These findings can help us to understand the consequences of interindividual microbiota variation for dietary responses and microbiota changes associated with disease states.IMPORTANCE Lactate is formed by many species of colonic bacteria, and can accumulate to high levels in the colons of inflammatory bowel disease subjects. Conversely, in healthy colons lactate is metabolized by lactate-utilizing species to the short-chain fatty acids butyrate and propionate, which are beneficial for the host. Here, we investigated the impact of continuous lactate infusions (up to 20 mM) at two pH values (6.5 and 5.5) on human colonic microbiota responsiveness and metabolic outputs. At pH 5.5 in particular, lactate tended to accumulate in tandem with decreases in butyrate and propionate and with corresponding changes in microbial composition. Moreover, microbial communities with low numbers of lactate-utilizing bacteria were inherently less stable and therefore more prone to lactate-induced perturbations. These investigations provide clear evidence of the important role these lactate utilizers may play in health maintenance. These should therefore be considered as potential new therapeutic probiotics to combat microbiota perturbations

Specific substrate-driven changes in human faecal microbiota composition contrast with functional redundancy in short-chain fatty acid production

The Rowett Institute and Biomathematics & Statistics Scotland receive financial support from the Scottish Government Rural and Environmental Sciences and Analytical Services. Nicole Reichardt was funded by a Scottish Government Strategic Partnership on Food and Drink Science. We would like to thank Donna Henderson for carrying out GC analysis and Alan Walker for help and advice with bioinformatic sequence analysis. Supplementary information is available at ISME Journal’s website.Peer reviewedPostprin