Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou, China.
Key Laboratory of Tropical Marine Bio-resources and Ecology and Key Laboratory of Science and Technology on Operational Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Microbiol Spectr. 2023 Jun 15;11(3):e0039823. doi: 10.1128/spectrum.00398-23. Epub 2023 Apr 26.
Understanding the biogeographical and biodiversity patterns of bacterial communities is essential in unraveling their responses to future environmental changes. However, the relationships between marine planktonic bacterial biodiversity and seawater chlorophyll are largely understudied. Here, we used high-throughput sequencing to study the biodiversity patterns of marine planktonic bacteria across a broad chlorophyll gradient spanning from the South China Sea across the Gulf of Bengal to the northern Arabian Sea. We found that the biogeographical patterns of marine planktonic bacteria complied with the scenario of homogeneous selection, with chlorophyll concentration being the key environmental selecting variable of bacteria taxa. The relative abundance of , the SAR11 clade, the SAR116 clade, and the SAR86 clade significantly decreased in habitats with high chlorophyll concentrations (>0.5 μg/L). Free-living bacteria (FLB) and particle-associated bacteria (PAB) displayed contrasting alpha diversity and chlorophyll relationships with a positive linear correlation for FLB but a negative correlation for PAB. We further found that PAB had a narrower niche breadth of chlorophyll than did FLB, with far fewer bacterial taxa being favored at higher chlorophyll concentrations. Higher chlorophyll concentrations were linked to the enhanced stochastic drift and reduced beta diversity of PAB but to the weakened homogeneous selection, enhanced dispersal limitation, and increased beta diversity of FLB. Taken together, our findings might broaden our knowledge about the biogeography of marine planktonic bacteria and advance the understanding of bacterial roles in predicting ecosystem functioning under future environmental changes that are derived from eutrophication. One of the long-standing interests of biogeography is to explore diversity patterns and uncover their underlying mechanisms. Despite intensive studies on the responses of eukaryotic communities to chlorophyll concentrations, we know little about how changes in seawater chlorophyll concentrations affect free-living bacteria (FLB) and particle-associated bacteria (PAB) diversity patterns in natural systems. Our biogeography study demonstrated that marine FLB and PAB displayed contrasting diversity and chlorophyll relationships and exhibited completely different assembly mechanisms. Our findings broaden our knowledge about the biogeographical and biodiversity patterns of marine planktonic bacteria in nature systems and suggest that PAB and FLB should be considered independently in predicting marine ecosystem functioning under future frequent eutrophication.
了解细菌群落的生物地理和生物多样性模式对于揭示它们对未来环境变化的响应至关重要。然而，海洋浮游细菌生物多样性与海水叶绿素之间的关系在很大程度上仍未得到充分研究。在这里，我们使用高通量测序技术研究了横跨南海、孟加拉湾到北阿拉伯海的广泛叶绿素梯度范围内海洋浮游细菌的生物多样性模式。我们发现，海洋浮游细菌的生物地理模式符合均匀选择的情景，其中叶绿素浓度是细菌分类群的关键环境选择变量。在叶绿素浓度较高（>0.5μg/L）的生境中，相对丰度显著降低的有、SAR11 类群、SAR116 类群和 SAR86 类群。自由生活细菌（FLB）和颗粒相关细菌（PAB）的α多样性和叶绿素之间呈现出相反的关系，FLB 呈正线性相关，而 PAB 呈负相关。我们进一步发现，PAB 的叶绿素生态位宽度比 FLB 窄，在较高的叶绿素浓度下，只有较少的细菌类群受到青睐。较高的叶绿素浓度与 PAB 的随机漂移增强和β多样性降低有关，而与 FLB 的均匀选择减弱、扩散限制增强和β多样性增加有关。总之，我们的研究结果可能会拓宽我们对海洋浮游细菌生物地理的认识，并有助于理解在由富营养化引起的未来环境变化下，细菌在预测生态系统功能方面的作用。生物地理学的一个长期关注点是探索多样性模式并揭示其潜在机制。尽管对真核生物群落对叶绿素浓度的响应进行了深入研究，但我们对海水叶绿素浓度变化如何影响自然系统中自由生活细菌（FLB）和颗粒相关细菌（PAB）多样性模式知之甚少。我们的生物地理学研究表明，海洋 FLB 和 PAB 表现出截然不同的多样性和叶绿素关系，并表现出完全不同的组装机制。我们的研究结果拓宽了我们对自然系统中海洋浮游细菌生物地理和生物多样性模式的认识，并表明在未来频繁富营养化的情况下，预测海洋生态系统功能时，应将 PAB 和 FLB 分别考虑。
