Multistep mutagenic strain improvement in Aspergillus Carbonarius to enhance pectinase production potential.

ABSTRACT

Pectinase is one of the most important commercially synthesised enzyme having its application in several industrial sectors like food and beverages, fruit clarifications etc. A.carbonarius has the capacity to produce Exo-pectinase 50 U/ml by submerged fermentation process as per the previous study. The present study describes the improvement of previously identified fungal strain Aspergillus carbonarius for enhancement of pectinase production by inducing mutations using physical and chemical mutagens. Aiming to increase the potentiality in pectinase production, the parental strain was treated for three times with four mutagens - UV irradiation, Colchicine, Hydrogen peroxide and Ethidium bromide to obtain mutants. Mutants were selected based on higher enzyme activity, improved growth rates and varied morphology with increased pectinase production. All the surviving mutants were assessed quantitatively after first mutagenic treatment. The stability of the best mutants was tested by repeating the exposures for two times to obtain 3rd generation mutants. These mutants were tested quantitatively to assess the pectinase production. Of all the best mutants E8 showed maximum activity producing 65U/ml pectinase enzyme compared to wild and sister mutants. The wild strain of A. carbonarius is a low pectinase producing organism as per literature. This strain was successfully mutated to increase the productivity rate to 1.8 fold in comparison to wild strain. This overproduction and strain stability may be due to repeated mutagenic treatments.