title: Comparison of light and dark nitrogenase activity in selected soil cyanobacteria.
abstract: Frequency of heterocytes and nitrogenase activity (NA) under light and dark cultivation conditions was determined in 12 cyanobacterial strains isolated from various soil habitats. In spite of a high variability, significant differences in NA among the strains were found in response of light and dark cultivation. Relatively high NA (9.9-15.3 micromol/h C2H4 per g fresh mass) under light conditions and basal NA after 12 h of dark cultivation were detected in Anabaena, Nodularia, Tolypothrix, and 1 of Cylindrospermum strains. On the other hand, significantly lower NA (0.76-5.4 micromol/h C2H4 per g fresh mass) was found under light conditions in Trichormus, Nostoc and another Cylindrospermum strain; the activity completely disappeared after 12 h of dark cultivation. NA values were not directly related to the frequency of the heterocytes. The total NA of cyanobacterial colony was found to be probably independent of the number and/or position of heterocytes. Remarkable differences in NA between strains isolated from cultivated fields and strains originating from natural or non-cultivated soils were found.
authors.affiliation: Department of Botany, Faculty of Biological Sciences, University of South Bohemia, 370 05 Ceske Budejovice, Czechia. bubak@tix.bf.jcu.cz
authors.forename: P
authors.initials: P
authors.lastname: Hrouzek
authors.forename: A
authors.initials: A
authors.lastname: Lukesová
authors.forename: M
authors.initials: M
authors.lastname: Simek
mesh_terms: D000458:Cyanobacteria / Q000201:enzymology*; D003624:Darkness; D008027:Light; D009591:Nitrogenase / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D009591:Nitrogenase