Unrevealing variation of microbial communities and correlation with environmental variables in a full culture-cycle of Undaria pinnatifida

Bacteria are the most abundant organisms in natural environment and dominant drivers of multiple geochemical functions. Drawing a global picture of microbial community structure and understanding their ecological status remain a grand challenge. As a typical artificial process, aquaculture provides a large amount of foods and creates great economic benefits for human beings. However, few studies are aimed at the microbial community in the aquaculture environment of aquatic plants. We analyzed microbial communities from 21 water samples in a coastal aquaculture area during the whole cultural process of Undaria pinnatifida by using high-throughout sequencing of 16S rRNA gene. The progression of U. pinnatifida aquaculture can be divided into three stages, named Seeding, Growth, and Maturity, respectively. Microbial community structures in water of the aquaculture area were significantly changed during the progression of U. pinnatifida aquaculture. The relative abundance of Flavobacteriia and Thaumarchaeota classes increased in Growth stage, and β-proteobacteria and Acidimirobiia classes decreased with the growth of U. pinnatifida. Meanwhile, environmental factors shaping the microbial community structures were uncovered during the U. pinnatifida aquaculture by using canonical correspondence analysis and Mantel test, in which temperature, dissolved oxygen, pH and nitrogen could be the major influencing factors. In addition, the microbial functions based on KEGG pathways were predicted from the microbial community compositions by PICRUSt. The comparison of predicted functions suggested that Environmental Information Processing and Genetic Information Processing were the functional categories with the most obvious shift in abundance among different stages of U. pinnatifida aquaculture. The findings of this study allowed us to better understand the microbial community in coastal aquaculture systems and the impact of seaweed cultivation on coastal ecosystems.