Decoding the seminal microbial fingerprint and semen quality: insights from the first Greek pilot study

Area of Science:

• Microbiology
• Reproductive Health
• Genomics

Background:

• Human semen harbors a complex microbiome.
• Microbial composition may influence semen quality and male fertility.
• Comprehensive characterization using advanced sequencing is limited.

Purpose of the Study:

• To characterize the bacterial and fungal communities in human semen.
• To compare seminal microbiomes between normozoospermic and abnormal semen samples.
• To investigate the potential link between microbial dysbiosis and male reproductive health.

Main Methods:

• Pilot study analyzing 80 semen samples from 80 men.
• Samples classified into normozoospermic (n=48) and abnormal (n=32) groups.
• Microbial profiling using full-length 16S rRNA and ITS sequencing on Oxford Nanopore MinION.

Main Results:

• Distinct microbial profiles observed between normozoospermic and abnormal semen samples.
• Normozoospermic samples dominated by Bacillota; abnormal samples showed increased Campylobacteriota.
• Specific bacterial genera and species (e.g., Enterococcus faecalis vs. Campylobacter ureolyticus) differed significantly between groups.
• No fungal DNA detected in semen samples, despite successful fungal controls.

Conclusions:

• Significant differences in seminal microbiome composition correlate with semen quality.
• Microbial dysbiosis is potentially linked to impaired male reproductive health.
• Fungi appear rare or absent in human semen under physiological conditions.
• Long-read sequencing provides novel insights into the seminal microbiome.