METHANE OXIDATION BY METHANOTROPHS

甲烷氧化细菌（甲烷氧化菌）能够在甲烷上生长 作为它们唯一的碳和能量来源 它们在自然界中无处不在 环境，显然在碳循环中发挥着重要作用， 特定的栖息地。 除了利用甲烷的能力， 在实验室条件下，催化甲烷氧化的酶 （甲烷单加氧酶; MMO）还可共氧化多种非生长 包括直链和环状烃的底物，以及 卤化烃。 由于这些化合物中的许多是有毒的， 对研究这种共氧化现象有相当大的兴趣。 然而，在这方面， 该系统的一些关键方面还没有得到很好的理解。 取决于 生长条件已经观察到两种不同的MMO，一种可溶， 另一个与细胞膜有关。 膜相关MMO 具有相对窄的底物范围，而可溶性酶具有 更广泛的底物范围。 虽然膜相关MMO出现在 在大多数生长条件下，它是主要的活性， 被净化，很少有关于它的信息。 生物化学、遗传学或调控。 该项目的目标是进行膜的主要研究- 相关MMO甲烷氧化菌，以评估的意义， 甲烷氧化菌对有毒碳氢化合物解毒的潜力。 我们 我建议对这个问题采取双重办法。 一是 生物化学表征膜相关MMO的基因， 在生化研究中，并研究这个系统的调节。 这些 研究将提供必要的信息，以便开始了解 膜相关MMO在甲烷营养生理学和 共氧化过程

Methane-oxidizing bacteria (methanotrophs) are capable of growth on methane as their sole carbon and energy source. They are ubiquitous in the natural environment, and apparently play a significant role in carbon cycling in specific habitats. In addition to their ability to utilize methane, under laboratory conditions the enzyme catalyzing the oxidation of methane (methane monooxygenase; MMO) also cooxidizes a variety of non-growth substrates including straight-chain and cyclic hydrocarbons, as well as halogenated hydrocarbons. Since many of these compounds are toxic, it is of considerable interest to study this cooxidation phenomenon. However, some key aspects of this system are not well-understood. Depending on the growth conditions two different MMO's have been observed, one soluble and the other associated with the cell membrane. The membrane-associated MMO has a comparatively narrow substrate range, while the soluble enzyme has a much broader substrate range. Although the membrane-associated MMO appears to be the predominant activity under most growth conditions, it has not been purified and little information is available concerning its biochemistry, genetics or regulation. The goal of this project is to carry out a major study of the membrane- associated MMO in methanotrophs in order to assess the significance and potential of methanotrophs for detoxification of toxic hydrocarbons. We propose to use a dual approach to this problem. First, we will biochemically characterize genes for the membrane-associated MMO to assist in the biochemical studies, and to study regulation of this system. These studies will provide the information necessary to begin to understand the role of the membrane-associated MMO in methanotrophic physiology and in cooxidation processes.