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30？60%的浮游植物初级生产。虽然我们对海洋中细菌的多样性了解很多，但对自然组合中特定细菌群的代谢功能知之甚少。独立研究已经将细菌群落的结构和功能联系起来。特别是，关于不同系统发育类群细菌对溶解有机物（DOM）的消耗的信息很少，而溶解有机物（DOM）是细菌在海洋中重要的生态和生物地球化学作用。这项研究将确定一组细菌在DOM消耗中的作用，细胞噬菌？Flavobacter组。我们的假设是细胞吞噬？黄杆菌群在海洋DOM消耗中起着核心作用。我们将解决以下问题：(1)细胞吞噬？黄杆菌群占海洋浮游细菌丰度和生物体积的很大一部分。(2)细胞吞噬？黄杆菌群消耗的DOM化合物支持大部分细菌生产，并包含大部分DOM输入。(3)细胞吞噬？黄杆菌群对测量的细菌产量的很大一部分负责？文化吗?将采用独立的方法来测定河口和上升流环境中具有一系列DOM输入和细菌消耗的群落。细胞吞噬的相对丰度？黄杆菌群将采用荧光原位杂交（FISH）测定。细胞吞噬对DOM化合物的摄取？黄杆菌群将使用放射性标记的DOM化合物和微放射自显影结合FISH （MICRO?FISH）来确定。噬细胞的作用？通过确定哪些细菌群吸收H？胸苷和亮氨酸。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量的细菌生产和DOM消耗是更好地了解海洋碳循环的关键一步。

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.