Extracellular amylase activities of Rhizomucor pusillus and Humicola lanuginosa at initial stages of growth.

Among thermophilic fungi, Rhizomucor Pusillus and Humicola lanuginosa have been reported to be among the most prolific producers of amylase, an apparently heat stable enzyme vital to the incorporation of carbon from macromolecular sources such as starch. Yet the highest levels of extracellular amylase in starch-yeast cultures of these fungi were measured after most of the growth had occurred; pre-growth levels appeared to be very small. Since these low levels are the significant ones for growth, a procedure was devised to measure them: 1.162 x 10(-2) units (mg maltose/ml/min) were measured after two days of growth of R. pusillus and 6.230 x 10(-3) units measured after four days of the slower-growing H. lanuginosa. Re-assays of these after dialysis to remove most of the reducing sugars gave 1.689 x 10(-2) units and 1.234 x 10(-2) units, respectively, with all correlation coefficients 0.96 or better.