Analysis of bacterial community diversity within seven bait-microalgae

Abstract Microalgae are primary producers in aquatic environments, and their growth is often accompanied and affected by bacteria. Although there are some studies about the relationship between microalgae and bacteria, few studies focused on bait-microalgae. Based on 16S rDNA amplicon sequencing, bacterial community structure and composition associated with seven common bait-microalgae, including Isochrysis galbana 3009, I. galbana 3010, I. galbana 3011, Thalassiosira pseudonana 9005, T. pseudonana 9006, Nannochloropsis oceanica 0001 and N. oceanica 0141, were comprehensively analyzed. Our results indicated that bacteria affiliated with phylum Alphaproteobacteria and Gammaproteobacteria and genera Marinobacter, Oceanicaulis and Dinoroseobacter dominated in all these seven bait-microalgae. Based on alpha and beta diversity analysis, we were interested to found that there were significant differences in the bacterial community between different microalgal species, while the differences were relatively small among the same species. When further searching for putative effect of dominant bacteria on the growth of microalgae, we found that the growth of all these seven microalgae was all improved significantly during co-cultivation with Marinobacter sp. When I. galbana 3011 was co-cultured with other three dominant bacteria, including Algoriphagus sp., Dinoroseobacter sp., and Oceanicaulis sp., the growth was improved significantly to different degrees. Taken together, the present work fully characterized the bacterial community associated with seven bait-microalgae and had a tentative exploration of algae-bacteria interaction, which will help improve the yield and quality of bait-microalgae during their cultivation processes.