Benzo[a]pyrene induces microbiome dysbiosis and inflammation in the intestinal tracts of western mosquitofish (Gambusia affinis) and zebrafish (Danio rerio)

Benzo[a]pyrene (BaP) is one of the most well studied carcinogenic polycyclic aromatic hydrocarbons (PAHs) that has been associated with a wide range of toxic effects in aquatic organisms. In the present study, the mosquitofish and zebrafish were exposed to BaP (100 mu g/L) for 15 days. We analyzed the intestinal microbial community of mosquitofish and zebrafish using 16S rRNA gene amplicon sequencing and also performed transcriptional profiling of the inflammation pathway related genes in the intestinal tissues. Our results showed that BaP exposure induced similar changes to the composition of microbial community in mosquitofish and zebrafish. At the phylum level, the abundance of Proteobacteria decreased while the abundance of Firmicutes increased following BaP exposure. At the genus level, a common pathogenic genus staphylococcus significantly increased in the BaP treatment groups, compared to the control (DMSO, similar to 0.001% v/v). In addition, it was observed that BaP significantly increased the mRNA level of il1 beta in both mosquitofish and zebrafish. The transcript levels of il6, il8, il10 and ifnphi1 were significantly increased in zebrafish, however not in mosquitofish, following Bap exposure. Our findings suggest that BaP could induce microbiota dysbiosis and inflammation in the intestine of mosquitofish and zebrafish.