Harrison, Lesley Ann (1985) The characterisation of a cellulolytic microbial community isolated from soil. PhD thesis, University of Warwick.

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Abstract

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.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QK Botany Q Science > QR Microbiology S Agriculture > SB Plant culture
Library of Congress Subject Headings (LCSH):	Soil microbial ecology -- Research, Aspergillus fumigatus, Penicillium, Fusarium
Official Date:	June 1985
Dates:	Date Event June 1985 Submitted
Institution:	University of Warwick
Theses Department:	Department of Environmental Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Parry, J. B. ; Slater, J. H. ; Lynch, J. M.
Extent:	xiii, 176 leaves : illustrations, charts
Language:	eng

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