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Christensenellaceae is a family of subdominant commensal bacteria found in humans. It is thought to play an important role in gut health by maintaining microbial symbiosis. Indeed, these bacteria occur at significantly lower levels or are absent in individuals suffering from inflammatory bowel diseases (IBDs). Here, we explored if type species Christensenella minuta (strain: DSM 22607) could have the potential to help treat IBDs. We assessed key properties displayed by the bacterium using a combination of in vitro and in vivo assays. We found that while C. minuta is a strict anaerobe, it is also oxygen tolerant. Additionally, we observed that the species produces high levels of acetate and moderate levels of butyrate. We performed deep phenotyping using Biolog microarrays. Using human intestinal cell lines, we discovered that C. minuta demonstrated strong anti-inflammatory activity, resulting in reduced levels of proinflammatory IL-8 cytokines via the inhibition of the NF-κB signaling pathway. Furthermore, C. minuta protected intestinal epithelial integrity in vitro. Finally, in two distinct animal models of acute colitis, C. minuta prevented intestinal damage, reduced colonic inflammation, and promoted mucosal healing. Together, these results indicate that C. minuta has potent immunomodulatory properties, underscoring its potential use in innovative microbiome-based IBD biotherapies.

Obesity is associated with gut microbiota dysbiosis, characterized by a high Firmicutes/Bacteroidetes ratio. Gut-dwelling bacteria of the Christensenellaceae family have been proposed to act as keystones of the human gut ecosystem and to prevent adipogenesis. The objectives of the present study were to demonstrate the antiobesity potential of a new strain of Christensenella minuta in preclinical models and explore related mechanisms of action. The antiobesity potential of C. minuta DSM33407 was assessed in a diet-induced obesity mouse model. Changes in hepatic lipid metabolism were explored using targeted transcriptomics. Effects on gut microbiota were further assessed in a humanized Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) model inoculated with obese fecal samples. Shotgun metagenomics was applied to study microbial community structures in both models. C. minuta DSM33407 protected from diet-induced obesity and regulated associated metabolic markers such as glycemia and leptin. It also regulated hepatic lipid metabolism through a strong inhibition of de novo lipogenesis and maintained gut epithelial integrity. In the humanized SHIME® model, these effects were associated with modulations of the intestinal microbiota characterized by a decreased Firmicutes/Bacteroidetes ratio. These data indicate that C. minuta DSM33407 is a convincing therapeutic candidate for the management of obesity and associated metabolic disorders.

Background There is increasing evidence that microbiome-based therapies can correct dysbiosis and reduce inflammation associated with Inflammatory Bowel Diseases (IBD). In particular, the human commensal family of Christensenellaceae bacteria has been reported as missing in several cohorts of Crohn’s disease patients, indicating that it may have a role in maintaining microbial symbiosis in this population. To assess its potential for IBD management, we used the reference type species Christensenella minuta DSM 22607 to examine its anti-inflammatory properties. Methods We first performed two distinct independent preclinical colitis models: i) a moderate DNBS-induced colitis model in mice and ii) a severe TNBS-induced colitis model in rats. To decipher the mechanisms of action of C. minuta underlying the observed effects, we determined its ability to produce short chain fatty acids (SCFA) at different growth phases and we assessed its capacity to modulate the inflammatory response of human colonic cells. Results Our results showed that in both rodent models, C. minuta prevented intestinal damages by decreasing macroscopic scores, reduced colonic inflammation by limiting neutrophils infiltration in the colon and stimulated mucosal healing. We also confirmed that C. minuta is a high acetate and moderate butyrate producer. Finally, we showed that C. minuta displayed potent anti-inflammatory properties by decreasing the secretion of the pro-inflammatory cytokine IL-8 through NF-kB inhibition in HT-29 cells. Conclusion Together, these results revealed for the first time the strong anti-inflammatory properties of C. minuta and confirm its high potential as an innovative microbiome-based biotherapy for IBD.

Fumonisin B1 (FB1 ) is a mycotoxin produced by several Fusarium species and is a very common contaminant of maize-based food and feed throughout the world. The selection and use of FB1 -degrading microorganisms appears as a promising alternative to cope with the problem of toxicity towards humans and livestock. High moisture maize grain silage, which is based on natural maize fermentation, could be an interesting reservoir of such microorganisms.; Results: Using an in vitro simulated silage model with FB1 naturally contaminated grains, we demonstrated a significant raw decrease in FB1 during ensiling process ascribed to biodegradation mechanisms. A panel of 98 bacteria and yeasts were isolated from this matrix and selected for their ability to use FB1 as the sole source of C and N. For nine of them, the ability to degrade FB1 in vitro was evidenced. Notably, two bacteria identified as Lactobacillus sp. were highlighted for their efficient FB1 -degrading capacity and production of hydrolysed FB1 as intermediate degradation metabolite.; Conclusion: Fermentation of high moisture maize grain contaminated with FB1 leads to a significant reduction of the toxin and allows the isolation of FB1 -degrading microorganisms that could further be used as FB1 decontaminating agents. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Fumonisin BUsing an in vitro simulated silage model with FBFermentation of high moisture maize grain contaminated with FB