Mutants of the cyanobacterium Anabaena sp PCC 7120 altered in nitrate transport and reduction

Citation
Ak. Rai et Sp. Tiwari, Mutants of the cyanobacterium Anabaena sp PCC 7120 altered in nitrate transport and reduction, CURR MICROB, 39(5), 1999, pp. 237-243
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
CURRENT MICROBIOLOGY
ISSN journal
0343-8651 → ACNP
Volume
39
Issue
5
Year of publication
1999
Pages
237 - 243
Database
ISI
SICI code
0343-8651(199911)39:5<237:MOTCAS>2.0.ZU;2-5
Abstract
Nitrate assimilation-defective mutants SP7, SP9, and SP17 of the cyanobacte rium Anabaena sp. PCC 7120 were isolated by use of transposon mutagenesis a nd screened on medium containing chlorate. SP7 and SP17 represented nitrate reductase-defective nature, while mutant SP9 appeared to be a regulatory m utant exhibiting pleiotropic behavior. Kinetics of nitrate uptake system ex hibited K-s values of 31-38 mu M for parent, SP7, and SP17 strains; however . mutant SP9 exhibited a high K-s value of 109.5 mu M. Defective nitrate re ductase was apparent in mutant SP7 and SP9, while mutant SP17 exhibited par tial defective nature. Methyl viologen-dependent NR activity in parent stra in presented a biphasic nature with K-m values of 0.13 and 2.47 mM, whereas a single K-m value (2.96 mM) was observed for mutant SP17. Mutant SP9 was also defective in nitrite uptake and reduction. Mutant strains exhibited de repressed nitrogenase activity in the presence of nitrate, while glutamine synthetase activity remained unaltered.