Browsing by Author "Assefa Fassil"

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    Isolation and Characterization of Aerobic Cellulose-Degrading Microorganisns
    (Addis Ababa University, 1983-06) Assefa Fassil
    Seventeen species of cellulose-degrading fungi that fall into fifteen genera were isolated from decomposing plant matter, p;arden soil, arable soil and manure. They were Alternaria sp., Aspergillus ilayus, ~. niger, Cephalospor:ul!', sp., Chaetomium sp., Curvularia sp., Fusarium sp., Geotrichum sp., Helminthosporium sp., Penicillium sp., Pythium sp" Rhizopus sp., Stachbotrys sp., Trichoderml.!. sp. 1, Trichoderma sp. 2, Verticillium sp. and Zygorrhynchus sp. Gr01,th rate determination on filter 1)aper showed that A. niger, Chaetomium sp., ~urvularia sp., Helminthosporium sp., Rhizopu~ sp., Stachybotr12 sp., Trichoderma. sp. I and 2 and Zygorrhynchus sp., displayed abundant growth within 7-21 da~at pH 4.5, 7.2 and B.S. Out of the fungi tested, only eight isolates namely Cephalosporium sp., Curvularia sp., HelminthosporiuJ!l: sp., Pythium sp., Stachybotrys sp., Trichoderma sp. 2., Verticillium sp., and Zygorrhynchu~ sp., were found to elaborate free cellulase in the culture medium. High cellulase activity was found in Zygorrhynchus sp. at pH 7,2 and Stachybotrys sp., at pH 4.5. Low cellulase activity was shown by Cephalosporium sp., at pH 7.2 and Pythium sf., at pH II,S The effect of different cellulosic substrates on cellulase elaboration was tested on these organisms. The influence of cellobiose and glucose on the in vitro cellulase activity of ~ygorrhynchus sp., was tested. The type and concentrations of reducing sugars released in the enzyme hydrolysates of the eight species were evaluated.