Screening of alkaline protease production by fungal isolates from different habitats of Sagar and Jabalpur district (M.P)

Fungal isolates were screened for alkaline protease production on casein containing agar plates and identified by clear zones of casein hydrolysis around colonies. Totally 141 fungal isolates were used in primary screening of alkaline protease and out of these, only 108 test fungi were found to produce alkaline protease activity as indicated by production of zone of casein hydrolysis around the fungal colonies grown in pH 9 after 5 d of incubation at 28C. Thirty three test fungi were found to grow on casein containing medium (pH 9) but were unable to produce zone of hydrolysis. For the production of extracellular alkaline proteases in liquid cultures, a total of 10 proteolytic fungi were selected which showed relative enzyme activity (REA) in the range of ≥ 2.29–3 based on the screening results of their REA on solid media. Maximum enzyme activity of 119.48 U/mL was found in Aspergillus versicolor PF/F/107 at pH 9 and temperature of 28oC after an incubation of 96 h in orbital shaker (150 rpm). Enzymes produced from microorganisms that can survive under extreme pH could be particularly useful for commercial applications under high alkaline conditions.