Evaluation of the semen microbiome for fertility in men with obesity using next-generation sequencing

The study aimed to evaluate the microbial content and diversity in semen samples of men with obesity, determine the differences between infertile and fertile groups, and investigate the effect of seminal microbiota on semen parameters, sperm DNA fragmentation, sperm chromatin condensation, and total antioxidant capacity.

The study included thirteen infertile men with obesity as subjects and five fertile men with obesity as the control group (aged 18-55 years, body mass index > 30 kg/m²). The most abundant bacteria in both groups were seen to be belonging to the phylum of Bacillota, Pseudomonadota, Actinomycetota and Bacteroidota. The most common bacteria at the genus level were Pseudescherichia, Staphylococcus, Paenibacillus, Streptococcus, Klebsiella, and Moraxella, which had similar distributions in both groups. A negative correlation was observed between the percentage of aniline-positive sperm and motility (p < 0.0001), sperm concentration (p = 0.0001) and total sperm count (p = 0.001). It was found that Brevibacterium, Paenibacillus, Alistipes, Lactiplantibacillus, Rhizobacter, Sphingomonas and Venlonella genera were correlated with sperm DNA fragmentation; Pantoea, Devosia, Bacteroides, Acidovorax were correlated with total antioxidant capacity, Fusobacterium was correlated with the histone-rich sperm, and Corynebacterium, Hydrogenophaga, and Paenalcagenes were associated with body mass index.

Bacterial species in semen may play a role in male infertility by affecting semen quality, sperm DNA fragmentation or total antioxidant capacity.