Microorganisms degrading cyclic and short-chain alkanes under anoxic conditions

丙烷和丁烷是天然气和原油的重要组成部分。丙烷和丁烷通过世界范围内大约10,000次天然石油和天然气渗漏或作为工业活动的结果进入生物圈。它们作为好氧和厌氧微生物的底物，在这些渗漏点的碳循环中起着重要作用。虽然丙烷和丁烷的好氧降解已经得到了深入的研究，但对这些烷烃在缺氧条件下的降解却知之甚少。菌株BuS5是迄今为止唯一能在缺氧条件下降解丙烷和丁烷的纯培养物。菌株BuS5是一种中温、硫酸盐还原细菌，系统发育上隶属于三角洲变形菌门的Desulfosarcina-Desulfococcus群。迄今为止进行的生理测试表明，它只能使用丙烷和正丁烷作为生长基质。本项目旨在以菌株BuS5为模式生物，对丙烷和正丁烷的厌氧降解有更深入的了解。主要目标是(a)对菌株BuS5的基因组进行注释和分析，重点关注烷烃激活/降解酶/途径；基因组将通过F. Musat和S. Sievert的一个项目提供，该项目已获得联合基因组研究所（JGI）的资助；(b)短链烷烃培养菌株BuS5的蛋白质组学分析；(c)针对丙烷和丁烷活化酶的纯化和表征的酶学研究。

Propane and butane are important constituents of natural gas and crude oil. Propane and butane reach the biosphere through a worldwide estimate of 10,000 natural oil and gas seeps, or as a result of industrial activities. They play a significant role in carbon cycling at such seepage sites, serving as substrates for aerobic and anaerobic microorganisms. While the aerobic degradation of propane and butane has been intensively studied, relatively little is known of the degradation of these alkanes under anoxic conditions. Strain BuS5 is up to now the only pure culture that can degrade propane and butane under anoxic conditions. Strain BuS5 is a mesophilic, sulphate-reducing bacterium, phylogenetically affiliated with the Desulfosarcina-Desulfococcus group of the Deltaproteobacteria. Physiological tests conducted so far have shown that it can use only propane and n-butane as growth substrates. The present project aims at obtaining a deeper understanding of the anaerobic degradation of propane and n-butane using Strain BuS5 as a model organism. The main objectives are (a) annotation and analysis of the genome of Strain BuS5 with a major focus on the alkane activation/degradation enzymes/pathways; the genome will be available through a project by F. Musat and S. Sievert accepted for funding at the Joint Genome Institute (JGI); (b) proteomic analyses of Strain BuS5 grown with short-chain alkanes; and (c) enzymatic studies aiming at the purification and characterization of the propane- and butane-activating enzyme.