HYDROLYSIS OF FIBROUS COTTON AND REPRECIPITATED CELLULOSE BY CELLULOLYTIC ENZYMES FROM SOIL MICRO-ORGANISMS

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Abstract
The action of cell-free filtrates from Trichoderma koningii was examined on undergraded cellulose in the form of cotton fibers, on degraded cellulose in the form of cellulose powder reprecipitated from phosphoric acid and on the soluble cellulose derivative CM-cellulose. The cell-free filtrates compare favorably with intact cellulolytic microorganisms in producing complete solubilization of undergraded as well as of degraded types of cellulose. Enzymic solubilization of cotton fibers gives quantitative conversion into glucose. Cellobiase is present. The early enzymic breakdown of cotton fibers is characterized by the formation of very short fibers that increase to a maximum and disappear gradually by conversion into glucose. Disintegration of cotton fibers to short fibers is assisted by shaking, and within 20 hr. the enzyme converts a minor fraction (up to 16%) of substrate into soluble products and a major portion (80%) into insoluble short fibers. Maximum enzymic activity on cotton fibers occurs at about pH 5.0, measured by the formation of short fibers, and at about pH 3.8 on reprecipitated cellulose, measured by solubilization of the substrate. Gluconolactone, glucose and cellobiose fail to produce marked inhibition of the enzymic hydrolysis of cotton fibers to short fibers or of the solubilization of reprecipitated cellulose unless present in amounts comparable with or greater than the initial weight of these 2 forms of cellulose. The heavy-metal ions Cu2+, Hg2+ and Fe3+ at 2m[image] concentration give 80-100% decrease in the enzymic breakdown of cotton fibers, measured by the formation of short fibers. At the same concentration Hg2+ and Fe3+ but not Cu2+ also produce 70-100% inhibition of the solubilization of reprecipitated cellulose. The ability to hydrolyze cotton fibers to short fibers and CM-cellulose to sugars is completely lost after heating enzyme preparations for 10 min. at 71[degree].