Abstract

The present study aimed to obtain a fungal isolate and enhance its cellulolytic activity through various mutational techniques, focusing on achieving results comparable to those obtained from extensively researched isolates of Trichoderma sp. An Aspergillus niger Tiegh. strain was obtained from environmental samples collected in Vadodara, Gujarat, and its cellulolytic-enzyme production was assessed and found to be akin to Trichoderma viride and Trichoderma reesei. Utilizing rice straw in solid-state fermentation (SSF), this research evaluated optimal conditions for enzyme activity at diverse pH and temperatures for both wild-type and mutant strains modified employing NTG (Methylnitronitrosoguanidine), EMS (Ethyl Methane Sulphonate), and UV radiation treatments. NTG-induced mutations significantly enhanced enzyme yields, particularly at pH 5 and 27°C. The NTG-treated A. niger mutants exhibited remarkable increases in endoglucanase activity, achieving 30.36 Units/mL, which corresponds to an increase of 22.91 Units/mL (4.12-fold) compared to the untreated strain. Similarly, T. viride and T. reesei showed significant increases to 29.18 and 25.58 Units/mL, respectively. Also, A. niger NTG-treated mutants showed avicelase activity of 245.73 ± 14.9 Units/mLat pH 5 and 27°C, compared to untreated strains with 85.62 Units/mL, representing a 2.43-fold increase. Moreover, the addition of cellulose significantly boosted enzymatic activity, increasing endoglucanase activity in A. niger from 4.76 Units/mL to 6.29 Units/mL.The findings of this study highlight the capacity of NTG-mutagenesis to enhance the production of cellulase. This opens up encouraging prospects for optimizing the utilization of enzymes in industrial settings and promoting sustainable waste management via bioconversion technologies.

Key words: A. niger, cellulase, mutagenesis, solid-state fermentation, sustainable waste management