Anaerobic Microorganisms from Human Microbiota Produce Species-Specific Exometabolites Important in Heath and Disease

Potential role of small molecules of microbial origin (SMOMs) in human homeostasis is under intensive research. Today the data on chemical structure of microbiota’s metabolites are still limited as well as their mechanisms of participation in the systemic inflammation and regulatory processes in health and disease. We have previously shown that in sepsis the levels of some phenolic acids in the blood increase tens of times, while some other metabolites are reduced or entirely disappear. It is known that various diseases, especially critical ill state, usually associated with maximal shifts in the composition of indigenous anaerobic microflora. In this study the attempt was made to evaluate the potential input of pure culture of different species anaerobic bacteria in “in vitro” setting in human metabolome. The main objective of the present study was to determine individual contributions of anaerobes in the cumulative pool of lowmolecular-weight phenolic and carboxylic acids. The production of these metabolites by predominant species of human anaerobic flora has been studied by gas chromatography–mass spectrometry (GC–MS) analysis. It was demonstrated that, along with lactate, bifidobacteria and lactobacilli produced in vitro considerable amounts of phenyllactic and phydroxyphenyllactic acids. Clostridium spp. produced lactic and phenyllactic acids, as well as 2-hydroxybuturic acid. C. sporogenes, alternatively to C. perfringens, produced great quantities of phenylpropionic and phydroxyphenylpropionic acids. Bacteroides spp. turned to be powerful producers of succinic and fumaric acids and greatly contributed to the production of lactic acid. Eubacterium lentum produced lactic, phenyllactic, and succinic acids at high concentrations. The species-specific differences in the selective production of particular metabolites between indigenous and conventionally pathogenic human anaerobes may be useful for determining the composition of biocenosis and microbial associations, and can be used as well as in the design of novel probiotics.