Cellulase production by Aspergillus fumigatus MS13.1 mutant generated by heavy ion mutagenesis and its efficient saccharification of pretreated sweet sorghum straw

Abstract

Abstract Developing a potential strain with high cellulase yield and stable fermenting performance is an imperative way to overcome the enzyme costs limitation. A cellulose degrading fungus was isolated from the agricultural wastes and identified as A. fumigatus MS13.1. For further improving the production capacity of enzyme, the original A. fumigatus MS13.1 was subjected to mutagenesis with heavy-ion beams and mutant MS160.53 was selected. The MS160.53 exhibited higher filter paper (1.81 IU/ml) and β-glucosidase (1.65 IU/ml) activities than parent strain MS13.1, which increased by 40.3% and 15.1%, respectively. Soluble protein concentrations in supernatants from strain MS160.53 were reached 1.497 mg/ml at 240 h which were higher than that in the reported literature of A. fumigatus. In addition, the SDS-PAGE profiles revealed that more enzymes of mutant were secreted during fermentation compared with parent strain MS131.1. The crude enzyme were further applied for saccharification of pretreated sweet sorghum straw, where a dosage of 5 IU/g FPase produced high reducing sugar titers of 789.75 mg/g. SEM images revealed the obviously microstructural changes of straw after the pretreatment and enzymatic hydrolysis. Thus, the enzyme cocktails produced by A. fumigatus MS160.53 has great potential for the saccharification of pretreated biomass and further bioethanol production.