Strain improvement of Trichoderma viride for increased cellulase production by irradiation of electron and (12)C(6+)-ion beams.

Abstract

To improve cellulase production and activity, Trichoderma viride GSICC 62010 was subjected to mutation involving irradiation with an electron beam and subsequently with a (12)C(6+)-ion beam. Mutant CIT 626 was the most promising cellulase producer after preliminary and secondary screening. Soluble protein production and cellulase activities were increased mutifold. The optimum temperature, pH and culture time for the maximum cellulase production of the selected mutant were 35°C, pH 5 and 6days. The highest cellulase production was obtained using wheat bran. The prepared cellulases from T. viride CIT 626 had twice the hydrolytic performance with sawdust (83%) than that from the parent strain (42.5%). Furthermore, molecular studies demonstrated that there were some key mutation sites suggesting that some amino acid changes in the protein caused by base mutations had led to the enhanced cellulase production and activity. Mutagenesis with electron and (12)C(6+)-ion beams could be developed as an effective tool for improvement of cellulase producing strains.