In vitro study of ethanol production, ethanol tolerance, and antimicrobial susceptibility of gut microbes associated with liver diseases.

Endogenous ethanol (EtOH) production is a newly identified pathophysiological mechanism involved in metabolic dysfunction-associated steatohepatitis (MASH) and liver disease associated with hepatitis B virus (HBV). Therefore, the characterization of EtOH-producing species associated with liver disease could contribute to the development of gut microbiota-targeted approaches. We investigated EtOH production and tolerance, antimicrobial susceptibility and antimicrobial resistance gene(s) in 33 strains isolated in previous culturomics studies and belonging to species enriched in MASH, alcoholic hepatitis (AH) and HBV patients. Enterocloster clostridioformis, Thomasclavelia ramosa and Peptinophilus grossensis were identified as new EtOH-producing species associated with liver diseases. A strong association between EtOH tolerance and production was detected (p < 0.05). Yeast, Enterocloster species (strictly anaerobic bacteria) and Limosilactobacillus fermentum produced the highest concentrations of EtOH (0.8 to 3.3 g/L). The poorly absorbed drugs, amphotericin B, rifaximin and vancomycin together showed high in vitro susceptibility. Furthermore, E. clostridioformis EC38 harbored the vanB operon. New EtOH-producing species associated with liver diseases were identified thanks to culturomics. Notably, most of them are anaerobic bacteria. These findings underscore the need to further investigate anaerobic gut microbiota species enriched in liver diseases with the aim of developing gut microbiota-targeted therapies.