The effects of immobilization on the biochemical,physiological and morphological features of Anabaena azollae |
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Authors: | D. -J. Shi M. Brouers D. O. Hall R. J. Robins |
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Affiliation: | (1) Department of Biology, King's College London, Campden Hill Road, W8 7AH London;(2) AFRC Institute of Food Research (Norwich Laboratory), Colney Lane, NR4 7UA Norwich, UK;(3) Present address: University of Liege B22, Sart-Tilman, Liege, Belgium |
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Abstract: | Anabaena azollae, a presumptive isolate from Azolla filiculoides, was immobilized in polyurethane foam, hydrophilic polyvinyl foam and alginate. When viewed by low-temperature scanning electron microscopy a thick mucilage layer covered the surface of both cells and matrix; this closely resembles the mode of attachment of the symbiont Anabaena in the Azolla leaf cavity. The heterocyst frequency of the immobilized A. azollae doubled relative to free-living cells and reached a level of 14–17%. Immobilization induced increases in both hydrogen production via nitrogenase or hydrogenase and in the rates and stabilization of acetylene reduction (N2-fixation). Ammonia production by immobilized cells with L-methionine-D,L-sulfoximine (MSX) is greater than that of freeliving cells. Immobilized cells without MSX were, however, able to excrete ammonium at lower rates thus emulating the characteristic of the symbiotic cyanobacteria (A. azollae) in the leaf cavity of Azolla.Abbreviations Chl chlorophyll - GS glutamine synthetase - MSX L-methionine-D,L-sulfoximine - SEM scanning electron microscopy - PU polyurethane - PV polyvinyl |
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Keywords: | Anabaena(immobilization) Heterocyst frequency Hydrogen production Mucilage Nitrogenase (NH4+production) Polyurethane and polyvinyl foams |
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