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Title: The effects of environmental conditions on the growth, physiology and ultrastructure of the cyanobacterium Anacystis nidulans
Author: Parrott, Linda M.
ISNI:       0000 0001 3472 9172
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1980
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The effects of growth rate and light and carbon dioxide limitation on the growth, macromolecular composition, ultrastructure and carboxylase activity of the cyanobacterium Anacystis nidulans were determined using chemostat continuous-flow culture conditions over the dilution rate range, D-0.02 - 0,19 h ̄1. Under carbon dioxide-limiting conditions the culture showed the characteristic substrate-limited pattern of growth although tinder light-limiting conditions there was a rapid decrease in organism biomass with increasing dilution rate with the biomass concentration being proportional to the reciprocal of the dilution rate. Growth rate in particular had a significant effect on the macromolecular content, in terms of DNA, RNA, protein, pigment and lipid, of A, nidulans whereas the nature of the growth-limiting substrate also had a significant effect on the carbohydrate content indicating that this was the main storage product in this organism. Growth rate also had a significant effect on the RuBPCase activity of A. nidulans which tended to increase with increasing dilution rate under both limitations, except for high values obtained at very low dilution rates under carbon dioxide-limitation. The FEPCase activity tended to show an inverse correlation with that of RuBPCase activity whereas no pyruvate Case activity was obtained under any of the growth conditions examined. Ultrastructure studies showed that this organism had basically the same typical prokaryotic fine structure irrespective of the dilution rate or substrate-limitation. The only exception was the presence of large densely stained inclusion bodies, which were probably polyphosphate granules, at D-O.02 h ̄1 under carbon dioxide- limitation. Some of the cellular components, such as the thylakoids, polyhedral bodies and ribosomes, did, however, alter quantitatively. Competition studies of A. nidulans and the green alga Scenedesmus quadrlcauda showed that tinder carbon dioxide-limitation A. nidulans was the competitive dominant at all the dilution rates examined whereas under light-limitation A. nidulans was dominant at D-O.02 h ̄1 and S. quadricauda at D-0.035 and 0. 045 h ̄1.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology