New isolate of Trichoderma viride strain for enhanced cellulolytic enzyme complex production

Abstract

Singapore Totalisation Board; Ngee Ann KongsiA new Trichoderma viride stain was isolated from Singapore soil samples. Its mutants were developed by using ethyl methyl sulfonate (EMS) treatment and UV-irradiation followed by a semi-quantitative plate clearing assay on phosphoric-acid-swollen cellulose plates. Mutant EU2-77 proved to be the most promising extracellular cellulase producer among 20 mutants in a screening program performed in shake flask fermentation after plate screening. Soluble protein content, filter paper cellulase (FPase) activity, beta-glucosidase activity and endoglucanase (CMCase) activity of the fermentation broths of the mutant strain were increased to 1.67, 2.49, 2.16, and 2.61 folds, respectively, compared with the wild strain. This enzyme complex produced by mutant EU2-77 contained FPase (2.19 IU/ml), CMCase (16.46 IU/ml), beta-glucosidase (4.04 IU/ml), xylanase (42.37 IU/ml), and beta-xylosidase (0.12 IU/ml). The soluble protein concentration in the enzyme complex was 1.69 mg/ml. The hydrolytic capacities of fermentation supernatants of T. reesei Rut-C30, the wild strain T. vi ride NP13a and mutant T. viride EU2-77 were compared with the commercial enzymes on the hydrolysis of waste newspaper. The crude enzymes prepared by T. vi ride EU2-77 showed much higher hydrolysis performance than that from the commercial strain Rut-C30 and demonstrated much comparable hydrolytic performances with the commercial enzyme mixtures. T. vi ride mutant EU2-77 produced high levels of extracellular cellulases as well as beta-glucosidase, rendering the supplementation of beta-glucosidase unnecessary in waste newspaper hydrolysis. (C) 2010, The Society for Biotechnology, Japan. All rights reserved