Isolation and characterization of a metronidazole-resistant (Mtn-R) mutant strain of Nostoc muscorum affected in ammonium regulation of heterocyst formation and uptake hydrogenase activity |
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| Authors: | AP Kumar DT Singh HN Singh |
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| Affiliation: | School of Live Sciences, University of Hyderabad, Central University P.O., Hyderabad 500 134, Andhra Pradesh, India |
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| Abstract: | Abstract The metronidazole-resistant ( Mtn-R ) mutant strain of N. muscorum produced drug-resistant NADPH: ferredoxin (Fd) oxidoreductase and showed derepression of heterocyst formation and uptake hydrogenase activity in NH4+-medium. The observation of NH4+-repression in regulation of nitrogenase activity alone in the mutant strain suggests, that heterocyst formation and nitrogenase activity are regulated by two separate NH4+-repression control systems, one specific for heterocyst and uptake hydrogenase and the other for nitrogenase. The partial drug-resistant NADPH: Fd oxidoreductase enzymatic activity seems to be the reason for drug-resistant growth of the cyanobacterium in N2-medium and NH4+-medium. |
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