紫云英根瘤菌109菌株氢酶的诱导表达——氧呼吸参与调节(英文)

异养生长的紫云英根瘤菌,其吸氢活性的表达在很大程度上取决于耗氧速率。30个诱导系统的统计和回归分析表明:菌体吸氢活性的表达与耗氧速率之间存在有负相关性。添加碳水化合物,可导致吸氢表达的抑制和推迟,同时引起细胞生长量和耗氧速率的增加。但抑制程度与细胞生长量之间并无明显相关性,而往往与耗氧速率增加相关,氢酶表达时间是在耗氧速率降低到较低水平的时刻。向指数期培养物中添加能量解联剂CCCP(carbonyl cyanide—m—chlorophenylhydrazone)和DNP(2,4—dinitrophenol),降低耗氧速率,氨酶表达可去阻抑。试验还表明:马铃薯汁对吸氢表达有明显的促进效果,可解除某些碳水化合物的阻抑,使某些表型为Hup~-的菌株转变为Hup~+。

Expression of Hydrogenase System in Rhizobium astragalus Strain 109: Regulation by Rate of Oxygen Respiration

Expression of hydrogen uptake (Hup) activitywas found to be dependent on respiratory ratein the heterotrophic cells of Rhizobium astragalusstrain 109. Adding carbohydrates resulted inan increase of oxygen uptake rate, and simul-taneously, a repression of hydrogenase. Therepression of carbohydrates was alleviated byadding potato extract. Potato extract was foundto be able to activate the expression of hydro-genase and to convert some Hup strains intoHup~+ ones. It was shown that, in these cases,the respiratory rate decreased during cell growth.Experiments also showed that hydrogenase wasderepressed in the presence of energy uncouplerCCCP or DNP. According to the above resu-Its, it is suggested that the rate of energy pro-duction might be related to the regulation ofhydrogenase expression.