A Mix of Potentially Probiotic Limosilactobacillus fermentum Strains Alters the Gut Microbiota in a Dose- and Sex-Dependent Manner in Wistar Rats.

Multi-strain Limosilactobacillus (L.) fermentum is a potential probiotic with reported immunomodulatory properties. This study aimed to evaluate the composition, richness, and diversity of the gut microbiota in male and female rats after treatment with a multi-strain of L. fermentum at different doses. Thirty rats (fifteen male and fifteen female) were allocated into a control group (CTL), a group receiving L. fermentum at a dose of 10⁸ CFU (Lf-10⁸), and a group receiving L. fermentum at a dose of 10¹⁰ CFU (Lf-10¹⁰) for 13 weeks. Gut microbiota and serum cytokine levels were evaluated after L. fermentum treatment. Male CTL rats had a lower relative abundance of Bifidobacteriaceae and Prevotella and a lower alpha diversity than their female CTL counterparts (p < 0.05). In addition, male CTL rats had a higher Firmicutes/Bacteroidetes (F/B) ratio than female CTL rats (p < 0.05). In female rats, the administration of L. fermentum at 10⁸ CFU decreased the relative abundance of Bifidobacteriaceae and Anaerobiospirillum and increased Lactobacillus (p < 0.05). In male rats, the administration of L. fermentum at 10¹⁰ CFU decreased the F/B ratio and increased Lachnospiraceae and the diversity of the gut microbiota (p < 0.05). The relative abundance of Lachnospiraceae and the alpha-diversity of gut microbiota were negatively correlated with serum levels of IL1β (r = −0.44) and TNFα (r = −0.39), respectively. This study identified important changes in gut microbiota between male and female rats and showed that a lower dose of L. fermentum may have more beneficial effects on gut microbiota in females, while a higher dose may result in more beneficial effects on gut microbiota in male rats. [ABSTRACT FROM AUTHOR]