固氮鱼腥藻(Anabaena azotica Ley HB686)氮固定的能量和还原剂来源

SOURCES OF ENERGY AND REDUCTANT FOR NITROGEN FIXATION IN ANABAENA AZOTICA LEY HB686

某些外源碳水化合物提高固氮鱼腥藻的固氮能力.在光照和5%氧浓度条件下,分子氢促进固氮作用.光合抑制剂、呼吸链抑制剂和解偶联剂均抑制固氮酶活性,若同时加入葡萄糖,DCMU的抑制作用被解除,而对DBMIB和解偶联剂的作用影响甚微.固氮鱼腥藻固氮作用的还原剂与光合作用产生的碳化合物有关,能量主要由循环光合磷酸化供给.

Several exogenous carbohydrates were found to stimulate C2H2 reduction activity in A. azotica HB686. The stimulation in light was more distinct than in dark. H2-supported C2H2-reduction was strictly light-dependent and low O2concentration ( 5 % ) was indispensable. C2H2-reduction was suppressed by photosynthetic chain inhibitors. The inhibition with DCMU was lessened by addition of grucose, whereas with DBMIB was little affected. Electron transfer inhibitors for respiratory chain and uncoupler inhibited C2H2 reduction activity. The results showed that the reductant supporting nitrogenase activity ultimately came from carbohydrates generated by photosynthesis in the vegetative cell, and ATP for nitrogenase was mainly generated by cyclic photophosphorylation and was supplemented by oxidative phosphorylation in A, azotica HB686.