中文摘要：

紫色光合细菌由于其代谢途径的多样性,在环境中广泛分布,是生态系统中碳循环的参与者和推动者之一。但是,水稻土中紫色光合细菌群落结构的空间分异却鲜有报道。基于此,沿我国温度梯度带（纬度梯度：28.38°N—47.43°N）,采集了8个典型水稻土,利用PCR-DGGE指纹图谱和系统发育树分析揭示不同地点水稻土中紫色光合细菌群落的组成;结合多个环境因子,利用生物信息学,典范对应分析（Canonical Correspondence Analysis,CCA）和最小判别效应分析（Cladogram,LDA）明确水稻土中紫色光合细菌的空间分异规律。研究发现我国8个典型水稻土中紫色光合细菌主要由变形菌门（Proteobacteria）的α和β这两个分支组成,主要为紫色非硫细菌;p H和纬度都是驱动水稻土中紫色光合细菌群落结构分异的关键因子。该认知不仅有助于更好地揭示稻田关键功能微生物群的生物地理学分布,还有助于进一步探究我国稻田生态系统有机质转化的时空差异。

英文摘要：

Purple phototrophic bacteria （PPB） are a diverse group of Proteobacteria that can use sulfur, hydrogen, iron, or organic compounds as electron donors during light harvesting reactions. Because of their metabolic diversity, PPBs are distributed in a wide variety of ecosystems. They participate in, as well as drive, the processes of the carbon cycle in ecosystems. Among terrestrial ecosystems, paddy soils are a preferred PPB habitat. However, gaps exist in our knowledge about PPB community composition in paddy soil and spatial shifts across a large geologic scale. We studied the spatial distribution of PPB in nine representative paddy sites, along a large latitudinal gradient ranging from 28.38° N to 47.43° N in China, using PCR-DGGE fingerprinting and phylogenetic analyses. Mechanisms for the spatial shifts in community composition were further elucidated by canonical correspondence analyses and eladograms. It was found that the dominant paddy PPB guilds are purple non-sulfur bacteria, affiliated with alpha and beta branehes of Proteobacteria. Soil pH and air temperature （latitude） were the main environmental triggers that influenced PPB community composition in paddy soil. This knowledge will comprehensive help us to bert understanding er understand the key species in paddy soil. In addition of spatial shifts in the transformation of organic matter , this information will contribute to the along the Chinese latitudinal gradient.