SCREENING AND OPTIMIZATION OF CULTURAL PARAMETERS FOR AN ALKALINE PROTEASE PRODUCTION BY ASPERGILLUS TERREUS GR. UNDER SUBMERGED FERMENTATION

Abstract

An alkaline protease-producing fungus was screened from potato grown soil fields of Bangalore and identified as Aspergillus terreus gr. based on morphological and microscopic features. The selected growth medium contained casein (1%) as a sole source of carbon and nitrogen. The pH of the medium was adjusted to 10.0 using sodium carbonate in order to isolate alkalophilic fungi. The best process parameters found after optimization were 5 days of incubation period, initial pH of 10.0, incubation temperature of 37 °C, 2.0% inoculum size, 1.5% casein and 2.0% soybean meal as nitrogen source supplement. All the studied process parameters significantly (p < 0.05) influenced the protease production by the isolate. A 4.949 fold enhancement in protease production was achieved after optimization. The increased alkaline protease production by A. terreus gr. using cheap nitrogen source, its thermostable nature and the alkaline pH are features which suggest its application in the detergent industry.