Changes in the microbial communities of the rearing water, sediment and gastrointestinal tract of Lateolabrax maculatus at two growth stages

The spotted sea bass, Lateolabrax maculatus, is a commercially important fish species in China. Microbial communities have important effects on water environment stability and animal health. Therefore, in this study, we comparatively investigated the microbiota characteristics in the water, sediment and gastrointestinal tract of L. maculatus at two growth stages. 16S rDNA high-throughput sequencing analysis revealed that the microbial diversity of the sediment was higher than that of the water and gastrointestinal tract, but the diversity did not change with fish growth. In addition, the composition of dominant bacterial taxa is more complex in the water and sediment than in the gastrointestinal tract. Specifically, Proteobacteria and Bacteroides were the dominant bacteria in the intestine and culture environments, while Actinobacteria and Planctomycetes were dominant in the water, Chloroflexi and Acidobacteria were enriched in the sediment, and Firmicutes tended to colonize the gastrointestinal tract. Alternatively, some genera of putative pathogenic bacteria (Vibrio, Streptococcus, Escherichia-Shigella, Enterobacter and Staphylococcus) and beneficial bacteria (Bacillus and Lactobacillus) underwent obvious dynamic changes in the stomach and different sections of the intestine with fish growth, indicating that the prevention of pathogen infection needs to be strengthened in fish farming, especially for the regulation of fish gastrointestinal tract health. These results are helpful for health management and the development of probiotics for fish farming using microbiota characteristics.