New insights into how the sperm microbiome may influence fertility
Researchers at the University of California, Los Angeles have identified links between bacteria in the sperm microbiome and sperm movement. Findings appear in the journal Scientific Reports and suggest that certain microbes can alter how well sperm swim toward an egg.
In controlled lab experiments using human sperm samples, scientists observed that Lactobacillus iners, a bacterium commonly found in the male reproductive tract, can interfere with sperm motility. The study notes that higher levels of this bacterium in semen correlate with reduced swimming ability, a factor closely tied to male fertility.
Sperm motility plays a key role in fertility because it reflects the capacity of germ cells to reach and fertilize the egg. The researchers point out that Lactobacillus iners may contribute to a local inflammatory environment through the production of L-lactic acid, a chemical that could disrupt the conditions sperm need to move efficiently.
Beyond Lactobacillus iners, the UCLA team found a relationship between lower sperm concentration and the presence of certain microbes in the semen. Specifically, higher counts of Pseudomonas fluorescens and Pseudomonas stutzeri were more common in samples with reduced sperm concentration. These bacteria belong to the Pseudomonas group, yet not every member of this group affects fertility in the same way, underscoring the nuanced nature of the sperm microbiome.
Further analysis showed that all three Pseudomonas species examined, including Pseudomonas putida, appeared in semen samples from men with both normal and abnormal sperm concentrations. This suggests that the impact of these bacteria on fertility is not uniform and may depend on a combination of microbial balance and host factors.
The study emphasizes that the relationship between the sperm microbiome and fertility is complex. It highlights the importance of considering microbial communities as part of the broader biological environment that supports sperm health. The results point to potential pathways for future research aimed at preserving fertility by managing the microbial milieu within the reproductive tract.
In other notes, a separate and unrelated line of inquiry has discussed pistachios in relation to libido. Experts in nutrition have explored potential benefits of pistachios for sexual health, but this topic remains distinct from the microbial factors linked to sperm motility and fertility described in the UCLA study.