Variance analysis of intestinal bacterial community between healthy and diseased Trachinotus ovatus

In order to investigate the difference of the intestinal community structure and its relationship with environmental factors in response to disease, the intestines of healthy and diseased Trachinotus ovatus were used to analyze the bacterial community composition and diversity as well as the culture waters and pellet feed. The five samples were studied by using Illumina HiSeq high-throughput sequencing and biological information analysis method. Compared with the intestinal microflora of the healthy pompano, the relative abundances of Spirochaetes significantly increased in the diseased pompano, whereas, the Firmicutes and Bacteroidetes exhibited an opposite pattern. The bacteria species in diseased pompano intestine only accounted for 54.94% in healthy pompano. There was 73.46% of the OTUs in the healthy ovate intestine, the same as that in the culture waters, and 70.58% in the feed, while the percentage dropped to 17.98% and 38.95% in the diseased pompano. Notably, the disease pompano had a higher relative abundance of Vibrio ponticus than healthy pompano being 78.90% and 17.19%, respectively. In addition, the relative abundance of Photobacterium leiognathi in healthy pompano was 54.53%, but absent in diseased pompano. The intestinal bacterial composition was relatively stable but there were still some difference between healthy and diseased pompano. After the occurrence of disease, the bacterial diversity declined markedly. The culture water and feed had a close correlation with the healthy pompano intestine but low influence on diseased pompano in bacterial species composition.