花生根瘤菌L_(8-3)菌株氢酶活性的表达及化能自养生长

本文研究了花生根瘤菌L_(8-3)菌株氢酶活性的诱导、表达。在吸氢培养基(H-UM)中,氢酶表达的最佳O_2浓度是5％,诱导氢酶活性的最佳H_2浓度也是5％,H_2浓度继续增大到20％时,氢酶活性基本保持恒定,CO_2对氢酶活性没有影响。在无机盐/维生素培养基和5％O_2、10％H_2、5％CO_2及80％N_2的混合气体条件下,花生根瘤菌能进行化能自养生长。生长15天后,培养液中的菌体光密度、细菌数、菌体蛋白质含量及有机碳含量明显提高,氢酶活性比异养液体HUM培养时高10倍,比斜面HUM培养高35倍。用N_2分剐代替混合气体中的H_2或CO_2,菌体则不能生长,光密度、细菌数、蛋白质含量及吸氢活性没有变化。

EXPRESSION OF HYDROGENASE ACTIVITY AND CHEMOAUTOTROPHIC GROWTH OF RHIZOBIUM ARACHIS STRAIN L_(8-3)

A condition was described in which Rhizobium arachis strain Lg8-3 expressed high hydrogenase activity in free-living cultures. In HUM, high hydrogenase activity was induced under 5% O2 and 5% H2 · Hydrogenase activity decreased when O2 concentration was higher than 5%, but did not decrease when H2 concentration increased up to 20%. CO2 had no effect on expression of hydrogenase activity in heterotrophic growth.R.arachis can grow autotrophically in mineral salts/vitamins medium and gas mixture containing 5%O2, 10%H2, 5%CO2 and 80% N2 · Compared with heterotrophic growth, hydrogenase activity by autotrophic growth increased greater than 10 fold in liquid HUM and 35 fold in solid HUM.However,all of the indexes indicated above did not show any increase when N2 was used to replace H_2 or CO_2.