Bacterial Communities in Semen from Men of Infertile Couples: Metagenomic Sequencing Reveals Relationships of Seminal Microbiota to Semen Quality

Abstract

Some previous studies have identified bacteria in semen as being a potential factor in male infertility. However, only few types of bacteria were taken into consideration while using PCR-based or culturing methods. Here we present an analysis approach using next-generation sequencing technology and bioinformatics analysis to investigate the associations between bacterial communities and semen quality. Ninety-six semen samples collected were examined for bacterial communities, measuring seven clinical criteria for semen quality (semen volume, sperm concentration, motility, Kruger's strict morphology, antisperm antibody (IgA), Atypical, and leukocytes). Computer-assisted semen analysis (CASA) was also performed. Results showed that the most abundant genera among all samples were Lactobacillus (19.9%), Pseudomonas (9.85%), Prevotella (8.51%) and Gardnerella (4.21%). The proportion of Lactobacillus and Gardnerella was significantly higher in the normal samples, while that of Prevotella was significantly higher in the low quality samples. Unsupervised clustering analysis demonstrated that the seminal bacterial communities were clustered into three main groups: Lactobacillus, Pseudomonas, and Prevotella predominant group. Remarkably, most normal samples (80.6%) were clustered in Lactobacillus predominant group. The analysis results showed seminal bacteria community types were highly associated with semen health. Lactobacillus might not only be a potential probiotic for semen quality maintenance, but also might be helpful in countering the negative influence of Prevotella and Pseudomonas. In this study, we investigated whole seminal bacterial communities and provided the most comprehensive analysis of the association between bacterial community and semen quality. The study significantly contributes to the current understanding of the etiology of male fertility.

Seminal microbiome in men with and without prostatitis

“…In both studies, high numbers of anaerobic bacteria were found. Some studies have recently used the NGS method to detect bacteria in semen . Weng et al .…”

“…Weng et al . investigated the male partners of infertile couples, and found that the proportions of Lactobacillus and Gardnerella were higher in the normal samples, whereas that of Prevotella in the low‐quality samples . Hou et al .…”

Comparative genomic identification and validation of β-defensin genes in the Ovis aries genome

“…It is logical, given the abundance of amino acids and other nutritional substrates in basic seminal fluid, that it would promote bacterial growth. In fact, researchers now propose that this microbiome impacts directly on the etiology of infertility [49]. In this context, it now seems plausible to propose that β-defensins evolved to regulate the microbiome in seminal fluid and prevent the growth of bacterial populations that may be detrimental to either sperm quality or uterine health.…”

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“…In our previous work we compared human kinases and kinases of pathogens (Plasmodium, Trypanosoma, Leishmania) and showed that in spite of quite conserved structure of the catalytic domain and binding sites in particular, creation of selective inhibitors is possible [62]. The proposed classification of STPKs is the first step towards developing effective selective inhibitors of bacterial protein kinases.…”

“…Further analysis showed that only Anaerococcus was significantly associated with compromised sperm quality. Recently Weng et al have conducted a similar research using 96 samples [62], of which 60 had one or more defects in semen parameters. The rest 36 samples were normal and used as control.…”