深圳大鹏湾海域锥状斯氏藻赤潮期间细菌群落结构变化研究

目的:近年来,赤潮在我国的发生呈增加的趋势,并造成了极大的经济损失。过去研究赤潮发生的机理主要集中在理化因素的影响,而越来越多的证据表明仅凭借营养盐等环境因素并不能解释大部分赤潮现象,藻际微生物可能发挥着重要作用。本文跟踪观测了2010年7月深圳大鹏湾海域爆发的锥状斯氏藻赤潮生消过程中细菌群落丰度种类的变化,从微生物与赤潮藻相互作用的角度探讨了赤潮的生消过程,讨论了不同时期不同关键菌群的特殊作用,为解释赤潮爆发和消亡提供了新的视角,为赤潮的监控和防治新方法的建立奠定了理论基础。方法:本文按时间顺序共采集该赤潮9次样本,利用末端限制性酶切片段长度多态性分析(T-RFLP)等分子生物学方法,通过主成分分析、克隆文库的构建,研究了微生物群落的变化过程,并探讨了特定种属的微生物在赤潮发生、发展和消亡过程中的作用。结果:从浮游细菌丰度来看,随着锥状斯氏藻细胞数量的波动,浮游细菌总数也随之呈现相应的变化。从浮游细菌的种类来看,它们主要属于变形杆菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)。从浮游细菌的动态变化过程来看,赤潮生消过程中,浮游细菌群落呈现出一定的演替现象,特别是在赤潮后期,群落主成分变化尤为显著。从关键菌群的作用来看,属于γ变形杆菌门的Alteromonas sp.一直占有较高的丰度,赤潮中后期受到菌群相互作用导致比例下降,而赤潮后期其他关键菌群的丰度的增高可能是导致赤潮消亡的重要原因。结论:本文利用T-RFLP这一DNA指纹技术分析微生物群落结构和多样性特征,通过研究赤潮生消过程中藻际浮游细菌群落的动态变化,发现随着赤潮的发展,浮游细菌群落发生着相应的变化。结果说明赤潮藻体丰度数量的改变影响着浮游细菌群落的组成。相对地,细菌群落的适应调整迅速造成赤潮藻体局部生长环境的改变,从而影响赤潮的发展过程。

Structural Dynamic of Bacterial Community Associated with a Scrippsiella Trochoidea Bloomin Dapeng Bay of Shenzhen *

Objective： There has been an increasing tendency of HABs which has caused damage to economies in China in recent decades. Generally, algal blooms are closely associated with a wide variety of physical and chemical factors, but increasing attention has been gained to the role of biological interactions between these microbes and harmful algae in regulating the population of harmful algae. This study focuses on the bacterial community associated with S. trochoidea bloom occurred in Dapeng Bay of east Shenzhen in July, 2010, which investigates the processes of algal bloom in a new perspective, and establishes a theoretical foundation for monitoring and prevention of algal blooms. Methods： The dynamic of the community composition and the function of specific bacterial in this process had been demonstrated by using T-RFLP, cloning library and principal component analysis （PCA）. Results： The bacterioplankton counts in this study exhibits a clear corresponding response to the of fluctuations S. trochoidea abundance. The species of bacterioplankton mainly belong to Proteobacteria, Bacteroidetes and Firmicutes. From the point of dynamic changes of bacterioplankton in the processes of algal bloom, it shows a certain succession, especially in the final stage, changes of principal component of bacterioplankton community are particularly significant. Considering the value of significant bacteria, γ-Proteobacteria which belongs to the Alteromonas sp. always has a high abundance, and its proportion in the whole community decreases in the last stage of HABs. Therefore, the increase of the other significant species may be lead to the distinct of HABs. Conclusion： In the present study, based on the analysis of microbial community structure and diversity characteristics by using T-RFLP, we demonstrate that the bacterioplankton community change accordi- ng to the development of HABs. The results show that change of the abundance of algae in HABs can affect the composition of bacteriop- lankton communities. In contrast, the adaption of the bacterial community can change the surroundings enviroment of algae related to HABs which affects the processes of algal bloom further.