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OPTIMIZATION OF VOLUME OF FERMENTATION MEDIUM FOR THE PRODUCTION OF ALKALINE PROTEASE BY AN EMS MUTANT STRAIN OF BACILLUS SUBTILIS IH-72

HAMID MUKHTAR^* AND IKRAM-UL-HAQ

Abstract: The study deals with the effect of volume of culture medium on the enhanced production of alkaline protease by an EMS-mutant culture of Bacillus subtilis in a lab scale bioreactor and shake flasks. The laboratory scale bioreactor of 7.5 L capacity was employed for the microbial cultivation experiments in addition to 250ml Erlenmeyer flasks. The parental strain of Bacillus subtilis was improved by inducing mutations using Ethyl methane sulphonate (EMS). After EMS-mutagenesis, 14 most potent variants showing positive mutations were isolated and screened for enhanced production of alkaline protease in shake flasks. The maximum production of the enzyme was shown by an EMS-mutant viz., EMS-8 that was 9.53U ml^-1 and it was about 100% increase over the parental strain (4.82U ml^-1). The effect of the volume of fermentation medium in shake flasks and fermentor on the production of enzyme by the mutant strain was studied and it was found that optimum volume of fermentation medium in shake flasks and bioreactor was 20% and 60%, respectively. The maximum production of alkaline protease by the wild and mutant strains was 7.98 U ml^-1 and 15.52 U ml^-1, respectively.

Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan.

^*Corresponding author e-mail: hamidmukhtar@gcu.edu.pk