Phenotypic expression of ammonia-excreting mutants of Anabaena 7120 under nitrogen limitation |
| |
Authors: | Singh AP Tiwari DN |
| |
Institution: | (1) Algal Research Laboratory, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi-, 221005, India |
| |
Abstract: | Mutants of Anabaena 7120 defective in glutamine synthetase (GS) activity were isolated following transposon mutagenesis. Mutants M11, M55 and M73 showed about 60% less GS activity in N2-grown aerobic cultures than the wild-type strain and were resistant to the glutamate analogue l-methionine-dl-sulphoximine (MSX). These mutants had the capacity to excrete N2-fixed ammonia continuously into the culture medium and showed an enhanced level of aerobic nitrogenase activity. The intracellular ammonium pool generated in N2-grown cells of mutants was found to be less than that of the wild-type strain. Similarly, ammonium uptake by these mutants was 50% less in mutants compared to the wild-type, suggesting a possible role of GS in controlling this function. |
| |
Keywords: | Ammonia excretion glutamine synthetase activity GS-defective mutants N2-fixing cyanobacterium transposon mutagenesis |
本文献已被 SpringerLink 等数据库收录! |
|