The Ethanol-Producing Enterocloster bolteae and Limosilactobacillus fermentum are enriched in Nonalcoholic steatohepatitis

Abstract

Background: Non-alcoholic steatohepatitis (NASH) has become a major public health issue. In fact, it is one of the leading causes of disturbed liver function and liver transplantation worldwide. Its link with the intestinal microbiota is still topical, and the production of endogenous ethanol following dysbiosis of the microbiota - one of the mechanisms linked to the disease - has been shown in several studies. In this study, we analyzed stool samples from 41 NASH patients and 24 healthy controls using culturomics and 16S rRNA targeted metagenomics to identify the microbial profile associated with each group. Fecal ethanol concentration was also determined for all samples. Results: We identified 358 different bacterial species using the culturomics approach distributed into 11 phyla and 143 genera. With a significant difference, 12 appeared significantly more frequently in the NASH group and 4 more frequently in the control group. Finegoldia magna was the most detected in NASH patients (10/14 (71%)), and 2 ethanol producing strains: Limosilactobacillus fermentum and Enterocloster bolteae. Metagenomics shows an enrichment of Lactobacillus and Streptococcus and a microbial profile identical to that of the culture. With regard to the species, there was an elevated frequency of ethanol-producing bacteria in NASH patients, and the concentration of ethanol was also higher in the stools of NASH patients compared to healthy controls (bilateral Mann-Whitney test, p=value 0.0145). However, compared with metagenomics, only the culture showed enrichment of Enterocloster bolteae in NASH patients. Conclusions: Culturomics and metagenomics are complementary methods for exploring the microbiota. Our results suggest that enrichment of ethanol-producing bacteria in NASH patients may play an instrumental role in the pathogenesis of the disease.