Photoproduction of ammonium by immobilized mutant strains of Anabaena variabilis |
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Authors: | Nigel W. Kerby Stephen C. Musgrave Peter Rowell Sergey V. Shestakov William D. P. Stewart |
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Affiliation: | (1) AFRC Research Group on Cyanobacteria, The University, DD1 4HN Dundee, UK;(2) The Department of Biological Sciences, The University, DD1 4HN Dundee, UK;(3) Department of Genetics, Moscow State University, 119 899 Moscow, USSR |
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Abstract: | Summary Ethylenediamine (EDA) is toxic to the cyanobacterium Anabaena variabilis and inhibits nitrogenase activity. The inhibition of nitrogenase was prevented by pretreatment of cells with l-methionine-d,l-sulphoximine (MSX). Mutant strains of Anabaena variabilis (ED81, ED92), resistant to EDA, had low levels of glutamine synthetase (GS) biosynthetic activity compared with the wild type strain. ED92 had a low level of GS protein whereas ED81 had a similar level to that of the parent strain as estimated using antibodies against GS. Both strains fixed N2 and liberated NH4+ into the media. Following immobilization of the mutant strains, sustained photoproduction of NH4+ was obtained in air-lift reactors at rates of up to 50 mol NH4+ mg chl a–1 h–1, which were comparable to the rates obtained when immobilized cyanobacteria were treated with MSX.Abbreviations EDA 1,2-diaminoethane (ethylenediamine) - GS glutamine synthetase - MSX l-methionine-d,l-sulphoximine |
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