Preventive effect of paraprobiotic Enterococcus faecalis FK-23 on bisphenol A-induced sperm toxicity

Bisphenol A (BPA), a chemical commonly used in food containers, has been detected in human blood and atheromas. It induces oxidative stress and impairs reproductive function. Developing preventive strategies against its biological effects is therefore essential. This study investigated the protective effects of Enterococcus faecalis FK-23 against BPA-induced sperm dysfunction through suppression of oxidative stress in a rat model. Male Wistar rats were assigned to control, FK-23, BPA, and BPA + FK-23 groups ( n = 3– 6/group). Sperm motility was analyzed using a computer-assisted system, while reactive oxygen species (ROS) generation was assessed by chemiluminescence. Oxidative stress markers, including 4-hydroxy-2-nonenal (HNE)-modified proteins, were detected by western blotting and identified by LC-MS/MS. Plasma radical-scavenging capacity was evaluated using electron spin resonance. No significant differences were observed in general health indicators such as body weight among the groups. BPA exposure decreased sperm motility and increased ROS production in a time-dependent manner. FK-23 supplementation significantly attenuated these effects, particularly after 2 weeks. FK-23 also suppressed BPA-induced accumulation of HNE-modified proteins, including mitochondrial proteins. Moreover, while BPA reduced plasma antioxidant capacity by about 50%, especially hydroxyl and methyl radical scavenging, FK-23 preserved these activities. The paraprobiotic FK-23 ameliorated BPA-induced sperm dysfunction, by mitigating systemic oxidative stress. These findings indicate that FK-23 has potential as a protective dietary intervention against environmental toxicants that impair male fertility. • Heat-killed Enterococcus faecalis FK-23 exhibits in vivo antioxidant capacity. • FK-23 co-administration suppresses BPA-induced oxidative stress, thereby preventing sperm dysfunction. • FK-23 and BPA co-administration suppressed HNE accumulation. • Plasma radical scavenging activity was preserved by FK-23 intake.