THERMOSTABLE DEXTRANASES - SCREENING, DETECTION AND PRELIMINARY CHARACTERIZATION

Screening methods have been developed for detection of micro-organisms producing thermostable dextranases. They utilize the incorporation of Blue Dextran into agar or liquid culture media for isolation of activ e dextranase producers growing at temperatures above 55 degrees C. A v ariety of high temperature environments in sugar factories and natural ly occurring thermal water samples were excellent sources of dextranas e producers. A number of aerobic and anaerobic thermophilic bacteria, isolated from these sources, were found to produce thermostable dextra nases. Dextranases with the greatest thermostability were found in cul tures of anaerobic bacteria grown above 65 degrees C. Temperature opti ma were determined for several crude enzyme preparations, four of whic h exhibited temperature optima in the range 65-85 degrees C.