The Role of Hydrogen for <i>Sulfurimonas denitrificans’</i> Metabolism

Sulfurimonas denitrificans was originally isolated from coastal marine sediments. It can grow with thiosulfate and nitrate or sulfide and oxygen. Recently sequencing of its genome revealed that it encodes periplasmic and cytoplasmic [NiFe]-hydrogenases but the role of hydrogen for its metabolism has remained unknown. We show the first experimental evidence that S. denitrificans can indeed express a functional hydrogen uptake active hydrogenase and can grow on hydrogen. In fact, under the provided conditions it grew faster and denser on hydrogen than on thiosulfate alone and even grew with hydrogen in the absence of reduced sulfur compounds. In our experiments, at the time points tested, the hydrogen uptake activity appeared to be related to the periplasmic hydrogenase and not to the cytoplasmic hydrogenase. Our data suggest that under the provided conditions S. denitrificans can grow more efficiently with hydrogen than with thiosulfate.脱氮硫单胞菌（Sulfurimonas denitrificans）最初分离自近岸海洋沉积物。该菌可利用硫代硫酸盐与硝酸盐，或硫化物与氧气作为生长基质。近期对其基因组的测序结果显示，该菌编码周质[NiFe]-氢化酶（[NiFe]-hydrogenase）与细胞质[NiFe]-氢化酶，但氢在其代谢过程中的作用仍未明确。本研究首次通过实验证实，脱氮硫单胞菌确实能够表达具有功能性的吸氢活性氢化酶，并可利用氢气进行生长。实际上，在本实验设置的条件下，该菌在氢气基质上的生长速率与菌体密度均高于仅以硫代硫酸盐为单一基质的情况，甚至可在缺乏还原态硫化合物的环境中仅依靠氢气生长。在本实验的测试时间节点中，氢摄取活性似乎与周质氢化酶相关，而非细胞质氢化酶。本研究的数据表明，在本次实验条件下，脱氮硫单胞菌利用氢气进行生长的效率高于硫代硫酸盐。