Mechanisms for Growth of Sulfate-Reducing Bacteria under Syntrophic Conditions

厌氧环境分布在整个地球上，H2总是作为有机化合物分解的中间物存在。在自然条件下，某些能够消耗H2的厌氧细菌将H2浓度维持在阈值水平（硫酸盐还原环境为1-2 nM）。由于这一过程的全球意义，H2消耗的生理学是环境微生物学家感兴趣的。然而，在基因水平上研究这一点的能力直到最近才出现。科学家们现在正准备解决硫酸盐还原菌在自然条件下生长的机制问题。以G20脱硫弧菌为模式生物。最初的实验将包括筛选菌株G20的5760个转座子突变体，以便与消耗苯甲酸-产生H2的细菌合养菌（Syntrophus aciditrophicus）一起在H2上生长。筛选过程使用对标记诱变过程的修改。在共生生长过程中（在共培养中）不能在H2上生长的突变体将被表征以确定发生突变的基因。我们预计我们将用这种方法鉴定出10-20个功能和调控基因。功能基因将通过比较突变体之间的H2消耗动力学来表征，以确定这些蛋白质是否直接参与H2加工。更广泛的影响包括使用新的本科学习方法。此外，这些研究结果可以为开发氢气生产或消耗的生物过程提供有用的信息。

Anaerobic environments are distributed over the entire earth and H2 is always present as an intermediate in the decomposition of organic compounds. Under natural conditions, certain anaerobic bacteria capable of H2 consumption, maintain the H2 concentration at threshold levels (1-2 nM for sulfate reducing environments). The physiology of H2 consumption is of interest to environmental microbiologists because of the global significance of this process. However, the ability to study this at the genetic level has only recently emerged. Scientists are now poised to address the question of the mechanism for growth of sulfate reducing bacteria under natural conditions. Desulfovibrio desulfuricans G20 will be used as the model organism. Initial experiments will involve screening a library of 5760 transposon mutants of strain G20 for the ability to grow on H2 together with the benzoate-consuming-H2 producing bacterium Syntrophus aciditrophicus. The screening process uses a modification of the signature tagged mutagenesis procedure. Mutants unable to grow on the H2 produced during syntrophic growth (within the coculture) will be characterized to determine the gene that has been mutated. We predict that we will identify 10-20 functional and regulatory genes in this way. Functional genes will be characterized by comparing the kinetics of H2 consumption among the mutants in order to determine whether these proteins are involved directly in H2 processing. Broader impacts include the use of novel approaches to undergraduate learning. As well, results of these studies could provide useful information to aid in development of biological processes for H2 production or consumption.