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Effects of UV‐B and heavy metals on nitrogen and phosphorus metabolism in three cyanobacteria
Author(s) -
Yadav Shivam,
Prajapati Rajesh,
Atri Neelam
Publication year - 2016
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201500504
Subject(s) - cyanobacteria , anabaena , nitrate reductase , glutamine synthetase , nostoc , glutamate synthase , nitrogenase , mineralization (soil science) , nitrogen fixation , chemistry , diazotroph , environmental chemistry , phosphorus , microcystin , nitrogen cycle , metabolism , biochemistry , biology , enzyme , nitrogen , bacteria , glutamine , genetics , organic chemistry , amino acid
Cyanobacteria sp. (diazotrophic and planktonic) hold a major position in ecosystem, former one due to their intrinsic capability of N 2 ‐fixation and later because of mineralization of organic matter. Unfortunately, their exposure to variety of abiotic stresses is unavoidable. Comparative analysis of interactive effect of UV‐B and heavy metals (Cd/Zn) on nitrogen and phosphorus metabolism of three cyanobacteria ( Anabaena , Microcystis , Nostoc ) revealed additive inhibition ( χ 2 significant p < 0.05) of NH 4 + and PO 4 3− uptake whereas increase in nitrate uptake upon UV‐B + heavy metal exposure. Glutamine synthetase and Alkaline phosphatase activity was reduced after all treatments whereas Nitrate reductase activity showed slight stimulation in UV‐B and UV‐B + heavy metals treatment. Combination of UV‐B and metals seems more detrimental to the NH 4 + , PO 4 3− uptake, GS and APA activity. A significant stimulation in NO 3 − uptake and NR activity following exposure to UV‐B in all the three cyanobacteria suggests UV‐B‐induced structural change(s) in the enzyme/carriers. Metals seem to compete for the binding sites of the enzymes and carriers; as noticed for Anabaena and Microcystis showing change in K m while no change in the K m value of Nostoc suggests non‐competitive nutrient uptake. Higher accumulation and more adverse effect on Na + and K + efflux proposes Cd as more toxic compared to Zn.