DIFFERENT RESPONSE PATTERNS OF FISH FOREGUT AND HINDGUT MICROBIOTA TO HOST HABITATS AND GENOTYPES

Fish gut microbiota can be affected by factors such as diet, habitat, and genotype. However, whether the foregut and hindgut microbiota respond similarly to these factors is still ambiguous. Given the fact that foregut has more communication with fish habitat and food intake, we hypothesized that the foregut microbiota is possibly more affected by external factors (e.g., habitat), while the hindgut microbiota tends to be mainly influenced by the host itself (e.g., genotype). To test our hypothesis, the V4 region of the gut bacterial 16S rRNA gene was amplified and sequenced by the MiSeq platform. A total of 1,139,703 high-quality sequences and 7,698 OTUs (without singlets) were obtained. Results indicated that the major factors that affect the fish gut microbiota patterns were the gut sections and habitats, rather than fish species. The foregut microbiota was indeed more similar to the water microbiota than hindgut microbiota, whereas the hindgut microbiota between fish species showed relatively more differences than that of foregut microbiota. Therefore, foregut and hindgut microbiota exhibited different response patterns to the habitat environments and host genotypes. This finding extended our understanding of the maintenance mechanism of fish gut microbial biodiversity