Sarmiento Felipe B, Leigh John A, Whitman William B
Department of Microbiology, University of Georgia, Athens, Georgia, USA.
Methods Enzymol. 2011;494:43-73. doi: 10.1016/B978-0-12-385112-3.00003-2.
Methanogens are obligate anaerobic Archaea that produce energy from the biosynthesis of methane. These lithotrophic microorganisms are widely distributed in oxygen-free environments and participate actively in the carbon cycle. Indeed, methanogenesis plays a major role in the last step of the anoxic degradation of organic substances, transforming acetate, CO(2), and H(2) to methane. The vast majority of the known methanogens are classified as hydrogenotrophic because they use principally H(2) as the electron donor to drive the reduction of CO(2). Unlike many other cultured Archaea, many methanogens thrive in neutral pH, low salinity, and temperate environments. This has been a great advantage in cultivating these organisms in laboratory conditions and in the development of genetic tools. Moreover, the hydrogenotroph Methanococcus maripaludis is currently a model organism among Archaea, not only for its utility in genetic but also for biochemical and physiological studies. Over time, a broad spectrum of genetic tools and techniques has been developed for methanococci, such as site-directed mutagenesis, selectable markers, transformation methods, and reporter genes. These tools have contributed greatly to the overall understanding of this group of microorganisms and the processes that govern its life style. In this chapter, we describe in detail the available genetic tools for the hydrogenotrophic methanogens.
产甲烷菌是专性厌氧古菌，通过甲烷生物合成产生能量。这些化能无机营养微生物广泛分布于无氧环境中，并积极参与碳循环。事实上，产甲烷作用在有机物质缺氧降解的最后一步中起主要作用，将乙酸盐、二氧化碳和氢气转化为甲烷。绝大多数已知的产甲烷菌被归类为氢营养型，因为它们主要利用氢气作为电子供体来驱动二氧化碳的还原。与许多其他培养的古菌不同，许多产甲烷菌在中性pH值、低盐度和温和环境中茁壮成长。这在实验室条件下培养这些生物体以及开发遗传工具方面具有很大优势。此外，氢营养型马氏甲烷球菌目前是古菌中的一种模式生物，不仅因其在遗传学方面的用途，还因其在生物化学和生理学研究中的用途。随着时间的推移，已经为甲烷球菌开发了广泛的遗传工具和技术，如定点诱变、选择标记、转化方法和报告基因。这些工具极大地促进了对这组微生物及其控制生活方式的过程的全面理解。在本章中，我们详细描述了氢营养型产甲烷菌可用的遗传工具。
