Comparison of the Intestinal Bacteria Between Black Seabass Centropristis striata Reared in Recirculating Aquaculture System and Net Pen.

Determination of diversity and function of the bacteria in fish gut is essential to understanding the interaction between intestinal bacteria and their host organism. This study compared intestinal bacterial community of black seabass (Centropristis striata) hatched by the same breeding farm but reared in different aquaculture systems, an indoor recirculating aquaculture system (RAS) and an inshore net pen (INP). The fish were fed with formulated feed manufactured by same feed company. Bacteria in fish gut, formulated feed and seawater were identified by 16S rRNA high throughout sequencing (HTS). Total 1484 OTUs, which belonged to 34 phyla and 79 genera, were identified from fish gut, formulated feed and seawater. In fish gut, 24 phyla and 43 genera were identified. Proteobacteria, Fusobacteria, and Firmicutes dominated at the phylum level in fish gut in INP, while Proteobacteria and Firmicutes dominated in fish gut in RAS. Photobacterium, Vibrio, and Cetobacterium dominated at the genus level in fish gut in both INP and RAS. One OTU of Photobacterium occurred in all the fish gut samples, suggesting this bacterium might be the main component of the core microbiota. No significant difference was found in bacterial diversity in fish gut between INP and RAS, suggesting genetic background should be a primary factor determining intestinal bacterial community of black seabass. Bacterial diversity in seawater was high relative to that in fish gut and formulated feed, regardless in INP or RAS. The common OTU between fish gut and seawater was more than that between fish gut and formulated feed in INP, while the common OTU between fish gut and seawater was slightly less than that between fish gut and formulated feed in RAS. These results reveal that the bacteria in formulated feed and seawater could influence the bacteria in fish gut, and their priority in shaping intestinal bacterial community depended on the bacterial composition in feed and seawater. This study reveals that intestinal bacterial community of black seabass was influenced by both genetic background and environmental factors.