Effects of H2 and Formate on Growth Yield and Regulation of Methanogenesis in Methanococcus maripaludis
Effects of H2 and Formate on Growth Yield and Regulation of Methanogenesis in Methanococcus maripaludis
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DOI：
10.1128/jb.02141-12
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发表时间：
2013-04-01
影响因子：
3.2
通讯作者：
Leigh, John A.
中科院分区：
文献类型：
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作者：
Costa, Kyle C.;Yoon, Sung Ho;Leigh, John A.
氢营养型产甲烷菌的定义是生长所需的H-2。尽管有这个要求，许多氢营养菌也能够生长与甲酸作为电子供体产甲烷。虽然这些生物体对氢可用性的某些反应已经被表征，但对甲酸饥饿的反应尚未报道。在这里，我们报告说，在连续培养的甲烷球菌maripaludis在规定的营养条件下，生长产量相对于甲烷产量显着下降，无论是H-2过量或甲酸过量。几个突变体的生长产量的分析表明，这种现象发生独立的细胞内碳的存储或甲烷生成的转录反应。使用微阵列分析，我们发现，编码辅酶F-420依赖的甲烷生成步骤的基因的表达，包括两个甲酸脱氢酶之一，增加与H-2饥饿，但与甲酸发生在高水平，无论限制或过量。一个基因，编码H-2依赖性亚甲基-四氢甲喋呤脱氢酶，表达下降，无论是H-2限制或甲酸限制。第二甲酸脱氢酶，依赖于甲酰基甲烷呋喃脱氢酶，和钼运输的基因表达增加，特别是与甲酸限制。在这两种甲酸脱氢酶中，只有第一种能在甲酸过量的分批培养中支持甲酸盐的生长。
Hydrogenotrophic methanogenic Archaea are defined by an H-2 requirement for growth. Despite this requirement, many hydrogenotrophs are also capable of growth with formate as an electron donor for methanogenesis. While certain responses of these organisms to hydrogen availability have been characterized, responses to formate starvation have not been reported. Here we report that during continuous culture of Methanococcus maripaludis under defined nutrient conditions, growth yields relative to methane production decreased markedly with either H-2 excess or formate excess. Analysis of the growth yields of several mutants suggests that this phenomenon occurs independently of the storage of intracellular carbon or a transcriptional response to methanogenesis. Using microarray analysis, we found that the expression of genes encoding coenzyme F-420-dependent steps of methanogenesis, including one of two formate dehydrogenases, increased with H-2 starvation but with formate occurred at high levels regardless of limitation or excess. One gene, encoding H-2-dependent methylene-tetrahydromethanopterin dehydrogenase, decreased in expression with either H-2 limitation or formate limitation. Expression of genes for the second formate dehydrogenase, molybdenum-dependent formylmethanofuran dehydrogenase, and molybdenum transport increased specifically with formate limitation. Of the two formate dehydrogenases, only the first could support growth on formate in batch culture where formate was in excess.