好氧不产氧光合细菌在典型环境梯度下的多样性和调控适应机制研究

Aerobic anoxygenic photototrophic bacteria (AAPB) represent an important group of marine microorganisms inhabiting the euphotic zone of the ocean. They harvest light using bacteriochlorophyll (BChl) a and are thought to be important players in carbon cycling in the ocean. The distribution of AAPB in the global ocean has been well known, and the mixotrophy life style has been revealed by the genome of Roseobacter denitrificans Och 114. However, the control mechanisms of environmental factors to AAPB and their adaptation were few reported, and these were important for deeper understanding their ecological functions. Based on our previous knowledge and understanding for AAPB, we want to investigate the community structure and diversity of AAPB along the 'Changjiang estuary-Kuroshio-Warm pool (Western pacific)' environmental gradient using the high throughput sequence technology. It will give us some better and new understanding about the environmental control to AAPB and self-adaptation strategies. Our project would like to figure out two key important science problems: 1）the relationship between the community structure and diversity and the environmental factor (including physical, chemical and biological factors); 2) build the bridge between the physiological and biochemical characteristics of AAPB and the environmental adaptations via their genomic data.

好氧不产氧光合异养菌(AAPB)可以利用细菌叶绿素 a 捕获光能，在海洋碳循环中发挥了很重要的补充作用。目前AAPB在全球的分布规律已经被比较好的认识，而且它们的基因组也解释了其混合营养的生存方式。但到目前为止环境因素对其调控的机制和其自身的适应机制并不是非常清楚，而这些是深入了解AAPB生态功能的关键。本项目申请人拟利用高通量技术、大尺度的环境梯度和相对较齐全的环境参数去研究AAPB群落结构和多样性，意在揭示环境因子对AAPB的生态调控机制、深入探讨AAPB自身的环境适应和进化，给AAPB环境调控机制研究带来新的认识。本项目拟解决2个关键科学问题：1）在高通量、高分辨率下AAPB群落结构及多样性与环境调控因子（主要是被动适应因子，包括物理、化学和生物因子）的关系；2）利用AAPB基因组建立其生理、生化特征和其环境适应之间的桥梁，找出其主动的适应机制和进化过程。

好氧不产氧光合异养细菌（AAPB）广泛分布在上层海洋，其丰度可达总细菌的15%，在全球真光层海洋能量和碳循环中起到重要作用。本项目利用高通量测序技术研究了从长江口到西太海域大环境尺度下AAPB群落结构组成，并重点分析西太海域不同光照偏好的AAPB类群（例如：Erythrobacter属偏好强光，Citromicrobium属喜好弱光）。基于环境类群AAPB的分析结果，我们对这两类寡营养的AAPB细菌（Erythrobacter属和Citromicrobium属）基因组进行了比较分析。Erythrobacter属中的AAPB在进化上是离散分布的，光合基因的水平基因转移和丢失共同塑造了该离散分布特征。Citromicrobium属的AAPB含有两套的光合基因簇，而且还含有一套视紫质的光合能量系统，这为它们寡营养弱光的分布环境提供了某种适应机制。此外我们还诱导获得了Citromicrobium sp. JL354基因组中的原噬菌体，分析发现其在光合基因簇的丢失和获得中起到某种媒介作用。结合实验室历年的AAPB生态数据，我们整合了AAPB生态和基因组的简单数据库。本项目研究链接了AAPB生态与基因组信息，为认识AAPB群落结构、环境调控机制和进化过程提供了新的视角和资料。