RUI: Ecology and Physiology of Anoxygenic Phototrophic Prokaryotes in Microbial Mats

本项目的目标是：(1)了解微生物席中缺氧光养菌的生态，特别是在复杂的多层微生物席群落中缺氧光养菌层序的原因；(2)从潮间带和高盐地垫中分离和鉴定了普遍存在的丝状光养菌绿藻；(3)从半透明热垫中分离和表征先前未描述的含叶绿素a的丝状细菌和光养生物。这些在极端环境中发现的原核生物群落是前寒武纪主导生物圈的广泛叠层石群落的现代类似物。对构成这些现代草席群落的光养生物的生理学和生态学的了解，使我们能够深入了解环境条件的本质，以及构成5亿至35亿年前地球上存在的古代草席的微生物。这些目标将通过对存在多层群落的热垫和潮间带垫进行实地研究来实现。氧、硫化物和光对层序的影响将通过比较相邻垫层中表现出不同层序的氧、硫化物和光微剖面来确定。直接分离、梯度培养和选择性富集技术将被用于分离海洋绿藻和未描述的嗜热丝状光养菌。将对这些菌株进行鉴定，以确定它们与已知菌株的关系，以及它们作为古代形成叠层石的光养生物后代的意义。

The objectives of this project are: (1) to understand the ecology of anoxygenic phototrophs in microbial mats and in particular, the causes of the sequence of layers of anoxygenic phototrophic bacteria in complex multi-layered microbial mat communities; (2) to isolate and characterize the ubiquitous filamentous phototroph, Chloroflexus, from intertidal and hypersaline mats; (3) to isolate and characterize the previously undescribed filimentous bacteriochlorophyll a - containing phototrophs from translucent thermal mats. These prokaryotic communities found in extreme environments are modern analogs of extensive stromatolitic communities that dominated the biosphere during the Precambrian. An understanding of the physiology and ecology of the phototrophs comprising these modern mat communities gives us insight into the nature of the environmental conditions and the microorganisms that comprised the ancient mats that existed on earth from 0.5 to 3.5 billion years ago. These objectives will be met by conducting field studies on thermal and intertidal mats where multi-layered communities exist. The effects of oxygen, sulfide, and light on layering sequences will be determined by comparing oxygen, sulfide, and light microprofiles in adjacent mats that exhibit different layering sequences. Direct isolation, gradient culture, and selective enrichment techniques will be used to isolate the marine Chloroflexus and undescribed thermophilic filamentous phototroph. Characterization of these isolates will be done to determine their relationship to known strains and their significance as descendents of ancient stromatolite-forming phototrophs.