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Title: Heterotrophic growth of blue-green algae
Author: Khoja, T. M.
ISNI:       0000 0001 3598 7288
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 1973
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Twenty four strains of blue-green algae were screened for their ability to grow heterotrophically in complete darkness with sucrose. Eighteen of these strains proved capable of growth in the dark and all of these latter continued to grow on repeated subculture. Only six strains failed to grow in the dark and of these six, one was still viable after three months incubation in the dark. Among the organic substrates tested, sucrose (0.01M) was found to be the best substrate in allowing a considerable growth of the majority (ten out of eighteen) of the cultures in the dark. Chlorogloea fritschii and four other strains were selected for obtaining their growth rates under different environmental conditions. C. fritschii was further used in a comparison of the dark growth rates of three heterotrophic cultures: material first subcultured from light to dark, material subcultured from dark to dark and material after three years of subculturing in the dark. The growth rates (K) of all three heterotrophic cultures were found to be the same, thus suggesting that no physiological adaptation had taken place as a response to prolonged heterotrophic conditions. The addition of sucrose to cultures of C. fritschii of and of four selected strains in the light (500 lux and up to 4000 lux with C. fritschii) resulted in an increase of the growth rate (2). Growth of five strains incapable of growth in dark was significantly stimulated by sucrose at 500 and 1000 lux. Only Anabaena variabilis did not respond significantly to sucrose. Cultures grown in the dark were pigmented. Pigment analysis showed that the levels of phycocyanin and chlorophyll in dark-grown cells of selected strains are not appreciably lower than those in cells grown photoautotrophically at 500 lux- Unlike the cultures of C. fritschii which consisted of aseriate colonies only in the dark, all other strains consisted of filaments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available