DOM consumption by marine bacterioplankton: Is the Cytophaga-Flavobacter group important?

异养细菌在海洋的碳循环中起着核心作用，消耗的有机物相当于浮游植物初级生产量的30%-60%。尽管我们对海洋中细菌的多样性已经了解很多，但关于自然群落中特定细菌群代谢功能的信息很少，因为很少有培养物？独立的研究将细菌群落结构和功能联系在一起。特别是，关于不同细菌系统发育类群对溶解有机物(DOM)的消耗的信息很少，这是细菌在海洋中的一个重要的生态和生物地球化学作用。本研究将确定一组细菌在DOM消耗中的作用，即细胞吞噬黄杆菌群。我们的假设是，细胞吞噬黄杆菌群在海洋中DOM的消耗中起着核心作用。我们将解决以下问题：(1)细胞吞噬黄杆菌类群是否包含海洋浮游细菌丰度和生物量的很大部分？(2)细胞吞噬类？黄杆菌类群是否消耗支持大部分细菌生产并构成DOM输入的DOM化合物？以及(3)在所测量的细菌产量中，细胞吞噬黄杆菌是否占了很大一部分？培养？将使用独立的方法来分析河口和上升流环境中的群落，这些环境中的细菌输入和消耗的DOM范围很大。利用荧光原位杂交技术(FISH)测定细胞吞噬黄杆菌群的相对丰度。将使用放射性标记的DOM化合物和与FISH(微型FISH)相结合的显微放射自显影术来确定细胞吞噬黄杆菌群对DOM化合物的摄取。通过确定哪些细菌群摄取‘H？胸腺嘧啶核苷和’H？亮氨酸，将细胞吞噬黄杆菌类群对细菌生产的贡献与其他类群进行比较。DOM吸收是海洋碳循环的一个重要方面，因此确定哪些类型的细菌负责大部分细菌生产和DOM消耗是更好地理解海洋碳循环的关键步骤。

Heterotrophic bacteria play a central role in the carbon cycle of the oceans, consuming organic matter equivalent to 30?60% of phytoplankton primary production. Although we have learned much about the diversity of bacteria in the ocean, there is little information on the metabolic function of specific bacterial groups in natural assemblages as few culture?independent studies have linked bacterial community structure and function. In particular, there is little information on dissolved organic matter (DOM) consumption by different phylogenetic groups of bacteria, an important ecological and biogeochemical role of bacteria in the ocean.This study will determine the role of one group of bacteria in DOM consumption, the Cytophaga?Flavobacter group. Our hypothesis is that the Cytophaga?Flavobacter group plays a central role in DOM consumption in the ocean. We will address the following questions: (1) Does the Cytophaga?Flavobacter group comprise a large fraction of marine bacterioplankton abundance and biovolume? (2) Does the Cytophaga?Flavobacter group consume DOM compounds that support a large fraction of bacterial production and comprise much of the DOM input? and (3) Is the Cytophaga?Flavobacter group responsible for a large fraction of the measured bacterial production?Culture?independent approaches will be used to assay communities in estuarine and upwelling environments having a range of DOM input and consumption by bacteria. The relative abundance of the Cytophaga?Flavobacter group will be determined using fluorescence in situ hybridization (FISH). Uptake of DOM compounds by the Cytophaga?Flavobacter group will be determined using radiolabeled DOM compounds and microautoradiography coupled with FISH (MICRO?FISH). The contribution of the Cytophaga?Flavobacter group to bacterial production will be compared to other groups by determining which bacterial groups take up 'H?thymidine and 'H?leucine. DOM uptake is an important aspect of carbon cycling in the ocean, so determining which types of bacteria are responsible for the bulk of bacterial production and DOM consumption is a key step in developing a better understanding of the marine carbon cycle.