Bacillus licheniformis ameliorates Aflatoxin B1-induced testicular damage by improving the gut-metabolism-testis axis.

Global aflatoxin B1 (AFB1) contamination is inevitable, and it can significantly damage testicular development. However, the current mechanism is confusing. Here, by integrating the transcriptome, microbiome, and serum metabolome, we comprehensively explain the impact of AFB1 on testis from the gut-metabolism-testis axis. Transcriptome analysis suggested that AFB1 exposure directly causes abnormalities in testicular inflammation-related signalling, such as tumor necrosis factor (TNF) pathway, and proliferation-related signalling pathways, such as phosphatidylinositide 3-kinases-protein kinase B (PI3K-AKT) pathway, which was verified by immunofluorescence. On the other hand, we found that upregulated inflammatory factors in the intestine after AFB1 exposure were associated with intestinal microbial dysbiosis, especially the enrichment of Bacilli, and enrichment analysis showed that this may be related to NLR family pyrin domain containing 3 (NLRP3)-mediated NOD-like receptor signalling. Also, AFB1 exposure caused blood metabolic disturbances, manifested as decreased hormone levels and increased oxidative stress. Significantly, B. licheniformis has remarkable AFB1 degradation efficiency (> 90%). B. licheniformis treatment is effective in attenuating gut-testis axis damage caused by AFB1 exposure through the above-mentioned signalling pathways. In conclusion, our findings indicate that AFB1 exposure disrupts testicular development through the gut-metabolism-testis axis, and B. licheniformis can effectively degrade AFB1.