Schubotz Florence, Wakeham Stuart G, Lipp Julius S, Fredricks Helen F, Hinrichs Kai-Uwe
Department of Geosciences, University of Bremen, D-28359 Bremen, Germany.
Environ Microbiol. 2009 Oct;11(10):2720-34. doi: 10.1111/j.1462-2920.2009.01999.x. Epub 2009 Jul 16.
The stratified water column of the Black Sea produces a vertical succession of redox zones, stimulating microbial activity at the interfaces. Our study of intact polar membrane lipids (IPLs) in suspended particulate matter and sediments highlights their potential as biomarkers for assessing the taxonomic composition of live microbial biomass. Intact polar membrane lipids in oxic waters above the chemocline represent contributions of bacterial and eukaryotic photosynthetic algae, while anoxygenic phototrophic bacteria and sulfate-reducing bacteria comprise a substantial amount of microbial biomass in deeper suboxic and anoxic layers. Intact polar membrane lipids such as betaine lipids and glycosidic ceramides suggest unspecified anaerobic bacteria in the anoxic zone. Distributions of polar head groups and core lipids show planktonic archaea below the oxic zone; methanotrophic archaea are only a minor fraction of archaeal biomass in the anoxic zone, contrasting previous observations based on the apolar derivatives of archaeal lipids. Sediments contain algal and bacterial IPLs from the water column, but transport to the sediment is selective; bacterial and archaeal IPLs are also produced within the sediments. Intact polar membrane lipid distributions in the Black Sea are stratified in accordance with geochemical profiles and provide information on vertical successions of major microbial groups contributing to suspended biomass. This study vastly extends our knowledge of the distribution of complex microbial lipids in the ocean.
黑海的分层水柱产生了一系列垂直的氧化还原带，刺激了界面处的微生物活动。我们对悬浮颗粒物和沉积物中完整极性膜脂（IPLs）的研究突出了它们作为评估活微生物生物量分类组成生物标志物的潜力。化学跃层上方含氧水域中的完整极性膜脂代表了细菌和真核光合藻类的贡献，而无氧光合细菌和硫酸盐还原细菌则构成了更深层缺氧和无氧层中大量的微生物生物量。诸如甜菜碱脂和糖苷神经酰胺等完整极性膜脂表明缺氧区存在未明确的厌氧细菌。极性头部基团和核心脂类的分布显示，含氧区下方存在浮游古菌；甲烷营养古菌在缺氧区仅占古菌生物量的一小部分，这与之前基于古菌脂类非极性衍生物的观察结果形成对比。沉积物含有来自水柱的藻类和细菌IPLs，但向沉积物的传输具有选择性；细菌和古菌的IPLs也在沉积物中产生。黑海完整极性膜脂的分布与地球化学剖面一致分层，并提供了对构成悬浮生物量的主要微生物群体垂直演替的信息。这项研究极大地扩展了我们对海洋中复杂微生物脂类分布的认识。
