Streptococcus thermophilus FUA329 converts ellagic acid (EA) to urolithin A (Uro-A), which is not autonomously converted by the gut microbiota to produce highly bioavailable and multibiologically active Uro-A in urolithin metabotype 0 (UM-0) populations. We consider that Streptococcus thermophilus FUA329 has the potential to be developed as a probiotic. Therefore, we utilized S. thermophilus FUA329 for in vitro cofermentation with gut microbiota. The results revealed that strain FUA329 increased the production of EA-converted Uro-A during in vitro cofermentation with the human gut microbiota of different urolithin metabotypes (UMs), with a significant increase in the production of Uro-A in the experimental group of UM-0. In addition, changes in the in vitro cofermentation microbial community were determined using high-throughput sequencing. Strain FUA329 modulated the structure and composition of the gut microbiota in different UMs, thereby significantly increasing the abundance of beneficial microbiota in the gut microbiota while decreasing the abundance of harmful microbiota. Of greatest interest was the significant increase in the abundance of Actinobacteria phylum after the cofermentation of strain FUA329 with UM-0 gut microbiota, which might be related to the significant increase in the production of Uro-A.
Keywords: Streptococcus thermophilus FUA329; ellagic acid; gut microbiota; urolithin A; urolithin metabotypes.