Cellulases and xylanase of an anaerobic rumen fungus grown on wheat straw, wheat straw holocellulose, cellulose and xylan
The activities of cellulolytic and xylanolytic enzymes produced by an anaerobic fungus (RI) which resembled Neocallimastix sp. were investigated. Carboxymethylcellulase (CMCase), cellobiase, and filter paper (FPase) activities had pH optima of 6.0, 5.5 and 6.0, respectively. CMCase and cellobiase activities both had a temperature optimum of 50 degrees C, whereas FPase had an optimum of 45 degrees C. The pH and temperature optima for xylanase activity were pH 6.0 and 50 degrees C, respectively. Growth of the fungus on wheat straw, wheat straw holocellulose, or cellulose resulted in substantial colonization, with at least 43 to 58% losses in substrate dry matter and accumulation of comparable amounts of formate. This end product was correlated to apparent loss of substrate dry weight and could be used as an indicator of fungal growth. Milling of wheat straw did not enhance the rate or extent of substrate degradation. Growth of the RI isolate on the above substrates or xylan also resulted in accumulation of high levels of xylanase activity and lower cellulase activities. Of the cellulases, CMCase was the most active and was associated with either low or trace amounts of cellobiase and FPase activities. During growth on xylan, reducing sugars, including arabinose and xylose, rapidly accumulated in the medium. Xylose and other reducing sugars, but not arabinose, were subsequently used for growth. Reducing sugars also accumulated, but not as rapidly, when the fungus was grown on wheat straw, wheat straw holocellulose, or cellulose. Xylanase activities detected during growth of RI on media containing glucose, xylose, or cellobiose suggested that enzyme production was constitutive. Xylanase activity was mainly cell associated in these cultures, but there was a considerable increase in activity during fungal autolysis. (Refs. 33).
- Research Organization:
- Univ. Manchester, Manchester M13 9PL. Microbiology Group, Dept. of Cell and Structural Biology, School of Biological Sciences; Animal and Grassland Research Institute, Hurley, Maidenhead, Berkshire SL6 5LR, UK
- OSTI ID:
- 5537593
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 53:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CELLULASE
TEMPERATURE DEPENDENCE
FUNGI
CELLULOLYTIC ACTIVITY
GLYCOSYL HYDROLASES
XYLANASE
ARABINOSE
CELL CULTURES
CELLULOSE
ENZYME ACTIVITY
GLUCOSE
PH VALUE
SACCHARIFICATION
STRAW
TEMPERATURE EFFECTS
WHEAT
XYLANS
XYLOSE
ALDEHYDES
CARBOHYDRATES
CEREALS
CHEMICAL REACTIONS
DECOMPOSITION
ENZYMES
GRASS
HEMICELLULOSE
HEXOSES
HYDROLASES
HYDROLYSIS
LYSIS
MONOSACCHARIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
PENTOSES
PLANTS
POLYSACCHARIDES
SACCHARIDES
SOLVOLYSIS
140504* - Solar Energy Conversion- Biomass Production & Conversion- (-1989)