Optimization of medium and cultivation conditions forl-amino acid oxidase production byAspergillus fumigatus

Abstract

A fungal strain was selected from the microbial repository of the North-East Institute of Science and Technology, Jorhat, India, which could produce a high yield of l-amino acid oxidase. 18SrRNA, ITS1, 5.8SrRNA ITS2, and partial 28 S rRNA sequencing and phenotypic characteristics indicate that it belong to the species Aspergillus fumigatus (designated as P13). Maximum production of enzyme (59.55 × 10−3 U/mg dry cell mass) was obtained in a medium containing 10 g/L glucose, 4 g/L yeast extract, and 4 g/L ammonium sulfate, with 20 mmol/L of l-threonine as the inducer. The optimum temperature for enzyme production was 30 °C at pH 7.0, with a shaking speed of 200 r/min. At 96 h, the enzyme activity was maximum. The A. fumigatus P13 l-amino acid oxidase accepts a broad substrate range, and the maximum enzyme activity (20.41 × 10−3 U/mg dry cell mass) was obtained with 50 mmol/L of dl-tyrosine. In the literature, no reports have been found regarding the production of l-amino acid oxidase by A. fumigatus. The enzyme showed enantiomerically pure amino acid formation, which has tremendous demand in industrial applications.