16S rRNA amplicon from the bacterium, which associated with  Alexandrium minutum and removing alage cells by Sonication-filtration
total environment DNA was extracted from 30mL of microalage culture using MagicPure Stool and Soil Genomic DNA Kit (TransGEN Biotech Cat. No. EC801). The 16S rRNA gene were paired-end sequenced through Illumina HiSeq 2500 platform to investigate the composition of the microbial community by BGI (Beijing Genomics Institute, Shenzhen, China).