Abstract: Anaerobic switch-off of Nase activity in A. brasilense "Yu-62" cultured aerobically in liquid medium with glutamic acid as N source was described. CCCP inactivated Nase rapidly. Western blotting experiment demonstrated that the molecular basis of inactivation of Nase was the modification of the Fe protein subunit. The anaerobic condition reduced ATP/ADP ratio in the cells and switched-off the Nase activity. The restoration of aerobic condition gave rise to rapid increase of ATP/ADP ratio and Nase activity. CCCP reduced ATP/ADP ratio rapidly. Metronidazole, a low potential electron acceptor, inhibited Nase activity but has no effect on modification of Fe protein, however, caused a slight change of ATP/ADP ratio. Our experiments demonstrated that the change of ATP/ADP ratio in cells was a signal trigging the modification of Fe protein.

Key words: Gutian Formation, Liangang Guangdong, Fossil plants, Late Early Permain fusulinids