Mitigation of PFOA-Induced Developmental Toxicity in Danio rerio by Bacillus subtilis var. natto: Focus on Growth and Ossification

Perfluorooctanoic acid (PFOA) is a persistent environmental contaminant that resists biological degradation and accumulates in organisms. It disrupts zebrafish embryo development, affecting their heartbeat rate and locomotion. Meanwhile, probiotics are known to enhance the development and ossification of zebrafish embryos. In this study, we examined the toxic effects of PFOA on growth and bone formation in zebrafish and the potential of the probiotic <i>Bacillus subtilis</i> var. <i>natto</i> to counteract its toxicity. Larvae were exposed to 0, 50, or 100 mg/L PFOA from hatching to 21 days post-fertilization (dpf), with or without dietary probiotic supplementation (10⁷ CFU/larva/day), and they were sampled at 7, 14, and 21 dpf. PFOA exposure reduced standard length at 21 dpf, while the co-administration of probiotics mitigated these effects. Craniofacial cartilage defects appeared in larvae exposed to 50 mg/L PFOA at 7 and 14 dpf, while 100 mg/L PFOA impaired bone development at 7 dpf. Probiotics counteracted these abnormalities. PFOA also delayed ossification, correlating with the downregulation of <i>col10a1a</i>, <i>runx2b</i>, and <i>cyp26b1</i>, while the probiotic treatment restored normal ossification. These findings improve our understanding of PFOA's detrimental effects on zebrafish growth and bone formation while demonstrating the protective role of probiotics against PFOA-induced developmental toxicity.