Equal yet different: a comparative characterization of Ruthenibacterium lactatiformans and Faecalibacterium prausnitzii

The gut microbiota plays a key role in maintaining human homeostasis. Of particular interest are 2 bacterial species of the family Oscillospiraceae: the well-studied Faecalibacterium prausnitzii, with proven anti-inflammatory properties, and the recently described Ruthenibacterium lactatiformans, whose functional potential remains insufficiently investigated. Despite their phylogenetic proximity, these species differ substantially in metabolic properties, associations with pathological conditions, and probiotic potential. The work aimed to conduct a comparative analysis of the characteristics of F. prausnitzii and R. lactatiformans and their interactions with the host, as well as to summarize data on possible mechanisms underlying their influence on the development of a wide range of diseases, including inflammatory bowel diseases, cardiovascular, metabolic, neurologic, and oncologic diseases.

Studies demonstrate that reduced abundance of F. prausnitzii serves as a reliable biomarker of dysbiosis and is associated with chronic inflammatory, autoimmune, and metabolic diseases. The protective role of this bacterium is primarily related to butyrate production and immunomodulation. In contrast to F. prausnitzii, associations of R. lactatiformans with pathological conditions are inconsistent. Increased abundance of this species correlates with both pathological states (stroke, active multiple sclerosis) and periods of clinical remission in certain diseases. At the same time, in experimental models, R. lactatiformans demonstrates protective, particularly metabolic, properties.

The decrease in F. prausnitzii abundance under pathological conditions is likely explained by its sensitivity to environmental changes such as tissue acidosis and oxidative stress. In contrast, R. lactatiformans, owing to greater metabolic plasticity (ability to produce lactate and acetate) and relative aerotolerance, is capable of adapting to these unfavorable conditions.

In conclusion, we support the hypothesis that the observed changes may reflect a dynamic dysbiotic shift and potential synergism rather than competition: R. lactatiformans, acting as an adaptive substrate supplier, may contribute to restoration of conditions favorable for subsequent colonization by butyrate-producing bacteria such as F. prausnitzii. This opens new perspectives for the development of probiotic strategies based on synergistic bacterial consortia.