期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2012
卷号：109
期号：45
页码：18547-18552
DOI：10.1073/pnas.1208605109
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The anaerobic archaeon Pyrococcus furiosus grows by fermenting carbohydrates producing H2, CO2, and acetate. We show here that it is surprisingly tolerant to oxygen, growing well in the presence of 8% (vol/vol) O2. Although cell growth and acetate production were not significantly affected by O2, H2 production was reduced by 50% (using 8% O2). The amount of H2 produced decreased in a linear manner with increasing concentrations of O2 over the range 2-12% (vol/vol), and for each mole of O2 consumed, the amount of H2 produced decreased by approximately 2 mol. The recycling of H2 by the two cytoplasmic hydrogenases appeared not to play a role in O2 resistance because a mutant strain lacking both enzymes was not more sensitive to O2 than the parent strain. Decreased H2 production was also not due to inactivation of the H2-producing, ferredoxin-dependent membrane-bound hydrogenase because its activity was unaffected by O2 exposure. Electrons from carbohydrate oxidation must therefore be diverted to relieve O2 stress at the level of reduced ferredoxin before H2 production. Deletion strains lacking superoxide reductase (SOR) and putative flavodiiron protein A showed increased sensitivity to O2, indicating that these enzymes play primary roles in resisting O2. However, a mutant strain lacking the proposed electron donor to SOR, rubredoxin, was unaffected in response to O2. Hence, electrons from sugar oxidation normally used to produce H2 are diverted to O2 detoxification by SOR and putative flavodiiron protein A, but the electron flow pathway from ferredoxin does not necessarily involve rubredoxin.|
