Comparative Microbiota Analyses in Rats Administered S. Typhimurium 14028 and its dam and seqA Mutants

Abstract In this study, the effect of the Salmonella Typhimurium 14028 strain and its two mutants with dam and seqA gene deletions on the rat gut microbiota was investigated. Descriptive RNA-sequencing studies were conducted on rectal swap samples taken at 3-day intervals for 9 days after oral dosing of bacterial strains to rats. As a result of bioinformatics and statistical analyses, a decrease in the relative ratio of Firmicutes at the phylum level (p < 0.05) and an increase in the relative ratio of Chlamydiae (p < 0.05) were determined in the rat groups treated with S. Typhimurium 14028 compared to the control group. Application of S. Typhimurium 14028 caused an increase in the relative ratio of Actinobacteria (p < 0.05). However, it was detected that the dysbiosis caused by the S. Typhimurium 14028 strain in favour of pathogens in the rat colon microbiota did not occur mostly in dam and seqA mutants. These general observations at the phylum level are maintained in all taxonomic groups analysed. At the species level, it was determined that the S. Typhimurium 14028 strain promoted especially Acinetobacter lwoffii, Jeotgalicoccus psychrophylus, Corynebacterium mastitis, and Corynebacterium stationi (seqA mutant also showed the same effect on this species) in the rat colon flora. On the other hand, S. Typhimurium 14028 typically led to the elimination of Blautia producta. These findings have proved that the S. Typhimurium 14028 strain causes dysbiosis in rat colon microbiota, and this ability is also lost in dam and seqA mutants of this strain.