Liver microbiome diversity and sex selection in male and female rats

Males and females exhibit gender dependence in disease occurrence. In recent research with healthy rats, we assessed the livers of male and female Sprague Dawley rats for the 16S ribosomal ribonucleic acid (rRNA) gene. The V3–V4 region of the 16S rRNA gene was amplified through polymerase chain reaction and sequenced using an Illumina NovaSeq 6000 platform. Sequences were assigned taxonomically using the Silva database, and the community diversity and relevance were analyzed. We detected 56,926.20 ± 16,991.65 effective tags of the 16S rRNA gene and clustered them into 15,845 kinds of amplicon sequence variants (2157.80 ± 461.52, 1632–2728), of which 10 rats shared only 127 kinds in common. The phylum Nitrospinota was exclusive to male rat livers, and the bacteria phyla Halanaerobiaeota, Latescibacterota, Caldisericota, and Abditibacteriota and the Archaea phylum Thermoplasmatota were exclusive to female rat livers. Female liver bacteria showed significantly higher richness but lower beta diversity than male liver bacteria (P < 0.05). Meanwhile, the liver microbiome showed distinct bacteria biomarkers and different bacteria correlations according to linear discriminant analysis effect size (LDA 2.0) and Spearman rank correlation analysis. According to redundancy analysis and the beta nearest taxon index null model, the distribution of several bacteria in the liver microbiome differed based on sex, and differences in community structure between the two groups were dominated by homogeneous deterministic processes rather than stochastic processes. Our results suggest that bacteria in the rat liver microbiome have the intrinsic property of sexual dimorphism.