Exploring the Role of Seminal Microbiota in Male Infertility via 16S rRNA Gene Sequencing

Abstract

Background: Recent research indicates that the human microbiome, including that of the male reproductive system, plays a crucial role in influencing male fertility. Changes in the seminal microbiota have been associated with impaired sperm function, inflammation, and a decrease in fertility potential. This study aimed to characterize and compare the seminal microbiota of infertile and fertile men using 16S rRNA gene sequencing, and to explore its relationship with semen quality.

Methods: Semen samples were obtained from 60 male participants, comprising 40 infertile men and 20 fertile age-matched controls. A standard semen analysis was conducted in accordance with the World Health Organization (WHO) 2021 guidelines. Bacterial isolates were cultured and underwent biochemical characterization. Genomic DNA was extracted from pure bacterial cultures, and 16S rRNA gene amplification was performed using universal primers (27F/1492R). Sequencing was followed by bioinformatic analysis to ascertain microbial taxonomy and diversity, with the sequences submitted to the NCBI GenBank database.

Results: Infertile men displayed seminal microbial profiles that were markedly different from those of fertile controls, characterized by decreased alpha diversity and a distinct microbial composition. Pathogenic genera such as Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus pasteuri, and Staphylococcus aureus were more abundant in the infertile group. These microbial changes were negatively associated with key sperm parameters, including motility, morphology, and concentration.

Conclusion: This study highlights a distinct seminal microbiota signature in infertile men, suggesting a potential role for specific pathogenic bacteria in the impairment of semen quality. Understanding the microbial composition of semen may enhance the diagnostic and therapeutic approaches for male infertility management.