ISSN:
1432-072X
Keywords:
Cyanobacteria
;
Immobilised cells
;
Desiccation
;
Water stress
;
Nitrogenase
;
ATP pool
;
Photooxidation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cells of Nostoc commune UTEX 584 from liquid cultures expressed an upshift in nitrogenase activity when immobilised on inert supports and exposed to matric water potentials between -1.10 and -99.5 MPa. Cells incubated at 0.10 MPa (aw=c 1.0) maintained increased activity for at least 48 h following immobilization. At water potentials below -23.1 MPa (aw=0.85), the upshift was transitory. Nitrogenase activity decreased rapidly when immobilised cells were incubated at lower values of ψm. Desiccated cells stored at -99.5 MPa (aw=0.50) underwent an upshift in nitrogenase activity, and in the size of the intracellular ATP pool, when rewetted with either distilled water or liquid MBo medium (ψo =-0.18 MPa). The upshift in nitrogenase activity was chloramphenicol-sensitive and was preceeded by a lag. The duration of the lag depended on the time taken to equilibrate cells to-99.5 MPa, the time desiccated, and the conditions of storage and rewetting. Cells that had no, or very low, nitrogenase activity when rewetted in air, showed a marked stimulation of nitrogenase activity in the presence of 5% v/v CO2 under both aerobic and anerobic conditions. When rewetted in the presence of 1% w/v glucose (ψo =-0.14 MPa), vegetative cells remained intact, but heterocysts underwent autolysis and nitrogenase activity was not detected, even in the presence of 5% v/v CO2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00446739
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