近岸海水中玫瑰杆菌类群多样性的年周期变化

Annual cycle variations in the diversity of coastal Roseobacter

摘要:

目的 玫瑰杆菌类群在海洋生态系统的物质循环和能量流动过程中发挥着重要的生态功能，但其环境响应及其群落构建机制随时间尺度的动态变化尚不明确。本文基于青岛近岸海域连续采集的60周海水样品，对玫瑰杆菌自由生活和颗粒附着类群的全年动态变化及其环境响应与群落构建机制进行了研究。方法 基于青岛近岸表层海水时间序列样品的16S rRNA基因扩增子测序，分析近岸海水中不同生活方式玫瑰杆菌类群的多样性年周期变化，并探究其与多种环境因子的相关性和群落构建机制。结果 在近岸表层海水中，玫瑰杆菌类群在总细菌古菌中的相对丰度呈现明显的季节性波动(2.64%-34.10%)，在冬、春季节显著高于夏、秋季节。根据其时间分布规律，可将玫瑰杆菌类群划分为夏秋型、冬春型以及暴发增长型。自由生活玫瑰杆菌类群的季节性规律更强，而颗粒附着类群表现出更高的多样性。温度、无机氮、无机磷等是影响玫瑰杆菌多样性的主要环境因素，且对颗粒附着类群变化的解释度(16.82%)高于自由生活类群(9.06%)。在群落构建方面，确定性过程对颗粒附着玫瑰杆菌类群的影响更大，说明环境变化对颗粒附着玫瑰杆菌类群的影响更明显。结论 本文从精细时间尺度探讨了玫瑰杆菌类群的动态变化及其环境驱动机制，揭示了其季节性分布规律，为深入理解这一重要海洋细菌类群的时空动态及其生态功能提供了重要的科学依据。

Abstract:

Objective Roseobacter play a significant ecological role in the material cycling and energy flow of marine ecosystems. However, their environmental responses on long time scales and community assembly mechanisms remain unclear. We collected samples over 60 consecutive weeks from the coastal waters near Qingdao to investigate the annual dynamics, environmental responses, and community assembly mechanisms of free-living and particle-associated Roseobacter.Methods The 16S rRNA gene amplicon sequencing was performed for the surface seawater samples to reveal the seasonal diversity variations of Roseobacter groups with different lifestyles. Furthermore, the correlations of Roseobacter with various environmental factors and the community assembly mechanisms were explored.Results In the surface seawater of the coastal zone, the relative abundance of Roseobacter in total bacteria and archaea exhibited significant seasonal fluctuations (2.64%-34.10%), with being markedly higher in winter and spring than in summer and autumn. Based on the temporal distribution patterns, Roseobacter groups can be classified into summer-autumn, winter-spring, and outbreak growth types. The free-living Roseobacter groups showed more pronounced seasonal patterns, while the particle-associated groups showed higher diversity. Temperature, inorganic nitrogen, and inorganic phosphorus were the main environmental factors influencing Roseobacter diversity, with their explanatory power on particle-associated groups (16.82%) being higher than that on free-living groups (9.06%). In terms of community assembly, deterministic processes had a greater impact on particle-associated Roseobacter groups, indicating that environmental changes had more significant effects on these groups.Conclusion This study, by examining the dynamic changes and environmental driving mechanisms of Roseobacter at a fine time scale, reveals their seasonal distribution patterns and provides scientific insights for understanding the spatiotemporal dynamics and ecological functions of this crucial marine bacterial group.