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Title: The characterisation of a cellulolytic microbial community isolated from soil
Author: Harrison, Lesley Ann
ISNI:       0000 0001 3539 1919
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1985
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A cellulolytic microbial community consisting of eight fungi and two bacteria was isolated from soil using a continuous flow enrichment technique. Each member of the community was grown in axenic culture and their levels of cellulase activity and rates of cellulose hydrolysis were determined. The strongly cellulolytic organisms were Aspergillus fumigatus and Penicillium simplicissimum. Results suggested that the other community members used the intermediates of cellulose hydrolysis produced by the primary cellulose degraders. The major B-glucosidase producing organisms were three Fusarium strains. Mixed and axenic culture studies indicated that there was no apparent synergism between members of the community during the degradation of either cellulose (Sigiucell type 20).hay or straw. Synergism was also lacking when the fungi were grown under different cultural conditions. The community degraded cellulose at a slower rate than did P. simplicissimum alone, and a lag in cellulase activity was evident. With 1ignocellulose, the community showed similar degradation rates to those of A. fumigatus and P. simplicissimum, although its levels of enzyme activity, with the exception of B-glucosidase, were lower. Culture conditions were found to have a strong influence on cellulase activity. With A. fumigatus, P. simplicissimum and the community grown in an unbuffered medium, increasing the cellulose concentration resulted in a decrease in cellulase activity, although endoglucanase and B-glucosidase levels were unaffected. Increasing the cellulose concentration in cultures grown in a buffered medium resulted in a dramatic increase in B-glucosidase activity. These levels were increased further by increasing the buffer molarity. Increasing the cellulose concentration in the buffered medium also resulted in an increase in the cellulase activity of P. simplicissimum and the community. Increased levels of B-glucosidase were produced by P.simplicissimum grown in a buffered medium with cellobiose as the carbon source. Studies of B-glucosidase location indicated that P. simplicissimum produced predominantly cel 1-associated enzyme activity which was not released into the growth medium until the latter stages of growth.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QK Botany ; QR Microbiology ; SB Plant culture