Intestinal microbiota signatures of common carp (Cyprinus carpio) after the infection of Aeromonas hydrophila

Abstract

Common carp is an important freshwater farmed fish species worldwide. Intensive rearing in aquaculture causes increasing susceptibility to various pathogens. One of the most frequently encountered pathogens is Aeromonas hydrophila, which has caused huge economic losses to the common carp industry. Extensive studies have been reported on the genetic mechanism underlying common carp against A. hydrophila at the molecular level, however, the influence of intestinal microbiota on host resistance to pathogen is less studied. In the present study, we analyzed the composition and biodiversity of intestinal microbiota in common carp following A. hydrophila infection by utilizing 16S rDNA sequencing. Collectively, the intestinal microbiota in common carp is diverse, but dominated by four phyla, Proteobacteria, Bacteroidetes, Fusobacteria and Firmicutes. The diversity and richness of microbiota was obviously decreased after infection of A. hydrophila. The composition and relative abundance of gut microbiota was significantly altered upon pathogenic invasion. The relative abundance of genera Cetobacterium and Vibrio were significantly increased in the infected groups. Further investigating the divergence of microbes between the resistant fish and susceptible fish showed that the relative abundance of Lactococcus, Akkermansia and Vibrio in resistant fish were significantly higher than that in both the susceptible fish and the control fish, indicating their potential correlation with the host resistance against pathogens. Our study could not only elucidate the dynamic changes in the common carp intestinal microbiota that occur in response to A. hydrophila, but also help us understand the underlying mechanism of intestinal microbial community in resisting pathogens and might suggest strategies for disease control in aquaculture.