Enhanced production of cellulase by Escherichia coli engineered with UV-mutated cellulase gene from Aspergillus niger UVMT-I

Abstract

Enhanced cellulase production was studied with ultraviolet mutagenesis and the mutated cellulase gene in E. coli DH5α was cloned for production under controlled conditions. Aspergillus niger inoculum was exposed to UV radiation for different time intervals. The UV exposure of 10 min to A. niger yielded 330 μmol/min/mg specific activity. The mRNA of mutant A. niger yielding maximum enzyme activity was isolated and used for the synthesis of cDNA. The cDNA prepared from mRNA was used for the PCR amplification of mutated cellulase gene with primers designed on the basis of a cellulase gene database from A. niger. The amplified cellulase gene was cloned into E. coli DH5α followed by expression in E. coli BL21. The cellulase activity by wild type A. niger, A. niger UVMT-I, and recombinant E. coli was compared by analysis of variance test. The specific activity of cellulase by recombinant E. coli was maximum (441 μmol/min/mg), followed by A. niger UVMT-I (330 μmol/min/mg) and wild type A. niger (96 μmol/min/mg).