Abstract. Heterotrophic bacteria process nearly half of the organic matter produced by phytoplankton in the surface ocean. Much of this organic matter consists of high molecular weight (HMW) biopolymers such as polysaccharides and proteins, which must initially be hydrolyzed to smaller sizes by structurally specific extracellular enzymes. To assess the relationships between substrate structure and microbial community composition and function, we concurrently determined carbohydrate abundance and structural complexity, bacterial community composition, and peptidase and polysaccharide hydrolase activities throughout the water column at four distinct stations in the western North Atlantic Ocean. Although the monosaccharide constituents of particulate organic matter (POM) were similar among stations, the structural complexity of POM-derived polysaccharides varied by depth and station, as demonstrated by polysaccharide-specific antibody probing. Bacterial community composition and polysaccharide hydrolase activities also varied by depth and station, suggesting that the structure and function of bacterial communities—and the structural complexity of their target substrates—are interlinked. Thus, the extent to which bacteria can transform organic matter in the ocean is dependent on both the structural complexity of the organic matter and their enzymatic capabilities in different depths and regions of the ocean.

中文翻译：

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北大西洋西部碳水化合物库存、酶活性和微生物群落之间的相关性

摘要。异养细菌处理海洋表层浮游植物产生的近一半有机物。这些有机物大部分由高分子量 (HMW) 生物聚合物组成，例如多糖和蛋白质，它们最初必须通过结构特定的细胞外酶水解成较小的尺寸。为了评估底物结构与微生物群落组成和功能之间的关系，我们同时测定了北大西洋西部四个不同站点的整个水柱中的碳水化合物丰度和结构复杂性、细菌群落组成以及肽酶和多糖水解酶活性。尽管各站的颗粒有机物 (POM) 的单糖成分相似，但 POM 衍生的多糖的结构复杂性因深度和站而异，如多糖特异性抗体探测所证明的那样。细菌群落组成和多糖水解酶活性也随深度和位置的不同而变化，这表明细菌群落的结构和功能及其目标底物的结构复杂性是相互关联的。因此，细菌转化海洋中有机物的程度取决于有机物的结构复杂性及其在海洋不同深度和区域的酶促能力。