Xia Xiaomin, Cheung Shunyan, Zhang Shuwen, Lu Yanhong, Leung Sze Ki, Shi Zhiyuan, Xu Huo, Gu Bowei, Tan Yehui, Zeng Huijun, Li Yang, Liu Hongbin
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.
Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China.
Water Res. 2024 Feb 1;249:120974. doi: 10.1016/j.watres.2023.120974. Epub 2023 Dec 4.
Noctiluca scintillans (red) is a widely distributed heterotrophic dinoflagellate and a prominent red tide forming species. This study investigated the effects of Noctiluca blooms on marine microbial diversity and functionality using multi-omics approaches. Our findings revealed significant differences in the community composition of Noctiluca-associated bacteria compared to those associated with autotrophic plankton and free-living bacteria in the surrounding seawater. The dominant bacterial groups within the Noctiluca-associated community shifted at various bloom stages, which could be attributed to changes in prey composition of Noctiluca. During the non-bloom stage, Burkholderiaceae, Carnobacteriaceae, and Pseudomonadaceae dominated the community, while Vibrionaceae became dominant during the bloom stage, and Saprospiraceae, Crocinitomicaceae, and Pirellulaceae thrived during the post-bloom stage. Compared to the non-bloom stage, Noctiluca-associated bacterial community at the bloom stage exhibited significant down-regulation of genes related to complex carbohydrate metabolism, while up-regulation of genes related to glucose transportation and utilization. Furthermore, we identified Vibrio anguillarum, a potential pathogenic bacterium to marine fish, as a major component of the Vibrionaceae family during the bloom stage. The occurrence of V. anguillarum associated with Noctiluca blooms may be attributed to the increased availability of its preferred carbon sources and its high capabilities in glucose transportation, motility and chemotaxis. Moreover, the presence of Vibrio infection genes (hap, hlyA, rtxA) encoding vibriolysin, hemolysin, and RTX (Repeats-in-toxin) toxin in the V. anguillarum genome, with the hap gene showing high expression levels during Noctiluca blooms, indicates an elevated risk of infection. This study underscores the unique composition of the bacterial community associated with red tide forming heterotrophic dinoflagellates and suggests that Noctiluca cells may serve as reservoirs and vectors for pathogenic bacteria, potentially posing a threat to fish-farming and the health of other marine organisms.
夜光藻（红色）是一种广泛分布的异养性甲藻，也是一种形成赤潮的主要物种。本研究采用多组学方法研究了夜光藻水华对海洋微生物多样性和功能的影响。我们的研究结果表明，与自养浮游生物和周围海水中的自由生活细菌相比，与夜光藻相关的细菌群落组成存在显著差异。夜光藻相关群落中的优势细菌类群在不同的水华阶段发生了变化，这可能归因于夜光藻猎物组成的变化。在非水华阶段，伯克霍尔德氏菌科、肉杆菌科和假单胞菌科在群落中占主导地位，而弧菌科在水华阶段成为优势菌，腐螺旋菌科、嗜铁钩端螺旋菌科和梨形菌科在水华后期大量繁殖。与非水华阶段相比，水华阶段与夜光藻相关的细菌群落中，与复杂碳水化合物代谢相关的基因显著下调，而与葡萄糖运输和利用相关的基因上调。此外，我们鉴定出鳗弧菌，一种对海洋鱼类有潜在致病性的细菌，是水华阶段弧菌科的主要组成部分。与夜光藻水华相关的鳗弧菌的出现可能归因于其偏好的碳源可用性增加以及其在葡萄糖运输、运动性和趋化性方面的高能力。此外，鳗弧菌基因组中存在编码弧菌溶素、溶血素和RTX（毒素重复序列）毒素的弧菌感染基因（hap、hlyA、rtxA），其中hap基因在夜光藻水华期间表达水平较高，这表明感染风险增加。本研究强调了与形成赤潮的异养性甲藻相关的细菌群落的独特组成，并表明夜光藻细胞可能作为病原菌的储存库和传播媒介，对养鱼业和其他海洋生物的健康构成潜在威胁。
