Bacterial communities in gills and intestines of yesso scallop (Patinopecten yessoensis) and its habitat waters in Changhai (Dalian, China)

Yesso scallop is a marine bivalve mollusc of economic importance in the coastline of northern China. The frequently outbreak of various diseases has heavily threatened the sustainable development of the scallop industry. The information about the bacterial communities inside and outside the body of Yesso scallop will provide insights into disease prevention, probiotic application and health aquaculture. In the present study, the diversity of bacterial communities in intestines, rectum and gills of Yesso scallop and its habitat waters were investigated. The bacterial diversity and richness in waters were higher than that in intestines, rectum and gills. The microbiota from intestines, rectum, gills of scallop and waters were clearly separated into four clusters by Non-metric multidimensional scaling and hierarchical cluster analysis, suggesting a microbiota selection of scallop at organ scale. Venn diagram suggested that the bacterial community in the body of scallop was more specialized than that in waters. High-throughput sequencing revealed that the main bacterial communities in intestine, rectum and gill were Firmicutes, Tenericute and Proteobacteria, Chlamydiae, Proteobacteria and Firmicutes, and Proteobacteria and Firmicutes, respectively. While the bacterial communities in waters mainly included Proteobacteria, Bacteroidetes and Cyanobacteria. Real-time PCR for bacterial load showed that the total bacterial abundance in waters was significantly higher than that inside the scallop body. The abundance of Bacteroides fragilis in rectum was significantly higher than that in intestines and gills. The results about the bacterial community inside and outside the body of Yesso scallop are helpful to better understand the relationship between the symbiotic bacteria of Yesso scallop and their habitat, and also provided critical information to develop strategies of disease prevention and probiotic application in scallop aquaculture.