The influence of weight and gender on intestinal bacterial community of wild largemouth bronze gudgeon (Coreius guichenoti, 1874)

Abstract

Background: Largemouth bronze gudgeon (Coreius guichenoti) is of economic importance in China, distributed in upstream regions of the Yangtze River in China. But it has recently dramatically declined and is close to elimination. However, there is little knowing about the character of its intestinal microbiota. This study was conducted to elucidate the intestinal microbiota of wild largemouth bronze gudgeon with different body weight and gender. Results: Thirty wild largemouth bronze gudgeon were measured for body length and body weight, and identified for male and female according to gonadal development, and thereafter the intestinal microbiota's were assessed by MiSeq sequencing of 16S rRNA genes. The results revealed that phyla Proteobacteria and Tenericutes were dominant in wild largemouth bronze gudgeon intestine independent of the body weight. Shannon's and Inverse Simpson's diversity indexes were significant (P < 0.05) different between male and female fish. The phylum profile in the intestine of male fish revealed that phylum Proteobacteria was dominant, in contrast to female fish where five phyla Tenericutes, Proteobacteria, Firmicutes, Fusobacteria and Spirochaetes were dominant. The genus profile revealed that genera Shewanella and Unclassified bacteria were dominant in male fish, while genus Mycoplasma was dominant in female fish. Conclusions: Our results revealed that the intestinal microbial community of wild largemouth bronze gudgeon was dominated by the phyla Proteobacteria and Tenericutes regardless of the different body weight, but the communities are significant different between male and female fish. These results provide a theoretical basis to understand the biological mechanisms relevant to the protection of the endangered fish species.