한국과 미국산 유독 와편모류 Karlodinium veneficum 배양주 간의 연관 세균 군집 비교 분석

Abstract

Based on recent findings, bacteria are capable of playing a key role in the formation of harmful algal blooms (HABs), but it is still unclear how bacteria can contribute on bloom formation due to lack of evidence. This study compared the toxic dinoflagellate Karlodinium veneficum particle-associated bacteria (PAB) and free-living bacteria (FLB) isolated from Korea (KR) and the United States (US) using the Oxford Nanopore MinION method and investigated the growth pattern of K. veneficum strains, which acted as growth-associated bacteria isolated within two strains. Consequently, the dominant group among the bacterial communities of the KR strain was found to belong to the genera Pseudomonas, Sulfitobacter, Algoriphagus and that of the US strain belonged to Marinobacter, Nioella, Seoheicola, and Robignitalea. PAB and FLB for the same K. veneficum strain was similar. Bacterial community analysis between KR and US confirmed that bacterial composition including PAB and FLB was not species-specific and apparently differed between these communities. However, the percentage of the genus Limnobacter increased significantly compared to the PAB in the FLB of both strains, which could be related to the algal substrates of K. veneficum, but further analyses are required. Subsequently, bacteria separated from KR and US were inoculated at a concentration gradient to identify the bacterial communities associated with growth. The growth improved compared to control in the KR culture inoculated with the genus Sulfitobacter, and two inoculated bacterial species belonging to the same genus showed a similar pattern. The PAB ratio of the KR strain increased as the genus Sulfitobacter ratio continued to grow, indicating that the strain induced growth by favoring the functional characteristics of Sulfitobacter. However, when two bacteria species belong to the genus Marinobacter were inoculated in the same way, the growth of both K. veneficum strains was inhibited. That is, substrates of Marinobacter are presumed to have induced cell lysis of the two strains, but further experiments are required to verify this.