Department of Geological and Environmental Sciences, Stanford University, CA, USA.
Geobiology. 2011 Jul;9(4):321-9. doi: 10.1111/j.1472-4669.2011.00285.x.
Organic biomarkers in marine sedimentary rocks hold important clues about the early history of Earth's surface environment. The chemical relicts of carotenoids from anoxygenic sulfur bacteria are of particular interest to geoscientists because of their potential to signal episodes of marine photic-zone euxinia such as those proposed for extended periods in the Proterozoic as well as brief intervals during the Phanerozoic. It is therefore critical to constrain the environmental and physiological factors that influence carotenoid production and preservation in modern environments. Here, we present the results of coupled pigment and nucleic acid clone library analyses from planktonic and benthic samples collected from a microbially dominated meromictic lake, Fayetteville Green Lake (New York). Purple sulfur bacteria (PSB) are abundant and diverse both in the water column at the chemocline and in benthic mats below oxygenated shallow waters, with different PSB species inhabiting the two environments. Okenone (from PSB) is an abundant carotenoid in both the chemocline waters and in benthic mats. Green sulfur bacteria and their primary pigment Bchl e are also represented in and below the chemocline. However, the water column and sediments are devoid of the green sulfur bacteria carotenoid isorenieratene. The unexpected absence of isorenieratene and apparent benthic production of okenone provide strong rationale for continued exploration of the microbial ecology of biomarker production in modern euxinic environments.
海洋沉积岩中的有机生物标志物为地球表面环境的早期历史提供了重要线索。由于其潜在的能够指示海洋光养分层缺氧事件的作用，因此，缺氧硫细菌的类胡萝卜素化学残余物对地球科学家具有特别的意义，这些缺氧事件可能发生在元古代的长时期内，也可能发生在显生宙的短暂期间内。因此，限制影响现代环境中类胡萝卜素产生和保存的环境和生理因素至关重要。在这里，我们介绍了从微生物主导的微分层费耶特维尔绿湖（纽约州）的浮游生物和底栖样品中收集的色素和核酸克隆文库分析的结果。紫硫细菌（PSB）在化变层的水柱中和含氧浅水层下方的底栖垫中都很丰富且多样化，不同的 PSB 物种栖息在这两个环境中。在化变层水域和底栖垫中都有大量的 okenone（来自 PSB）作为类胡萝卜素。绿硫细菌及其主要色素 Bchl e 也存在于化变层内和下方。然而，水柱和沉积物中却没有绿硫细菌类胡萝卜素异岩藻烯酮。异岩藻烯酮的意外缺失和 okenone 的明显底栖产生为在现代缺氧环境中继续探索生物标志物产生的微生物生态学提供了强有力的理由。
