期刊
RESEARCH IN MICROBIOLOGY
卷 152, 期 9, 页码 793-798出版社
EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
DOI: 10.1016/S0923-2508(01)01262-1
关键词
Escherichia coli; HybO; HybC; microaerobic growth; redox potential; hydrogenase 2
类别
The aim of this work was to study the influence of O-2 with special emphasis on low oxygen tension, the effect of H-2 under various conditions of oxygen tension and the influence of the redox potential in the growth medium on hydrogenase 2 of Escherichia coli. The hydrogenase activity and the content of the large (HybC) and small (Hyb0) subunits of hydrogenase 2 were compared during turbidostat cultivation in a wild strain and mutant HDK103 lacking hydrogenases 1 and 3. No hydrogenase 2 activity in the mutant HDK103 was observed under aerobic conditions, but it was maximal under anaerobic conditions and half-maximal at an oxygen tension of similar to4 mbar as is common for enzymes of anaerobic respiration. The content of hydrogenase 2 in both the strains was-maximal under anaerobic conditions. In the wild strain, H-2 addition enhanced hydrogenase activity and the Hyb0 content under microaerobic conditions only. Under anaerobic conditions endogenous H-2 production hindered this effect. Under aerobic conditions, the O-2-related negative effect seemed to dominate over the H-2-related positive effect. By contrast, in the mutant HDK103, hydrogen influenced neither hydrogenase 2 activity nor its content. A possible role of hydrogenase 1 in the response of hydrogenase 2 to hydrogen is discussed. Under conditions of different O-2 tension, hydrogenase activity in both strains correlated inversely with the value of the redox potential of the medium. The presence of H-2 changed this dependence. Thus, the value of the redox potential itself is not a controlling factor for hydrogenase 2. (C) 2001 Editions scientifiques et medicales Elsevier SAS.
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