PRODUCTION OF EXTRACELLULAR BETA-MANNANASES BY YEASTS AND YEAST-LIKE MICROORGANISMS

A new screening method for simultaneous detection of endo-beta-1,4-man nanase and endo-beta-1,4-xylanase producing microorganisms is describe d. Two differently dyed substrates Ostazin Brilliant Red-galactomannan and Remazol Brilliant Blue-xylan were incorporated into the same agar media. Decolorizing of one or both substrates around the cell colonie s indicates secretion of the corresponding enzyme(s). The method was u sed to screen 449 yeasts and yeast-like microorganisms belonging to 68 different genera. The secretion of endo-beta-1,4-mannanases and/or en do-beta-1,4-xylanases was found within 10 genera (42 positive strains out of 261 tested). A low frequency of occurrence of endo-beta-1,4-man nanase was observed within the genera Cryptococcus (1 positive strain out of 15 tested), Geotrichum (1 of 6) and Pichia (1 of 35). The highe st frequency of occurrence of endo-beta-1,4-mannanases was found withi n the genera Stephanoascus (2 of 2) and Aureobasidium (14 of 14). Stra ins hydrolyzing Ostazin Brilliant Red-galactomannan were cultivated in liquid media containing 1% locust bean gum. The best producers of ext racellular endo-beta-1,4-mannanases were found to be the strains of Au reobasidium pullulans.