Exploring ultraviolet and nitrous acid-induced mutagenesis of Rhizopus oligosporus for extracellular inulinase production under solid-state culture.

Abstract

This study details the synthesis and optimization of extracellular inulinase through solid-state fermentation using improved strain of Rhizopus oligosporus. The wild-type was procured from IIB culture bank and subsequently enhanced through UV-radiation and Nitrous acid treatments. The resulting mutant strain was subjected to further optimization for heightened enzyme production via solid-state fermentation. The substrate, pressmud (20 g), and moisture content (20 mL molasses) were carefully selected. Key parameters such as inoculum size, incubation time, and inulin concentration were optimized to maximize enzyme yield. Mutation procedures involved optimizing spore suspension, UV-radiation exposure duration, and the distance of culture plate from UV rays. Nitrous acid treatment, followed by resistance development using L-cysteine HCl, further refined the mutant strains. Evaluation through UV-Vis spectrophotometry and comprehensive characterization using SEM, FTIR, and XRD were conducted to compare the results between the wild-type and mutant strains. The mutant strain exhibited significantly higher inulinase activity (111 ± 0.49 U/ml) as compared to its wild-type counterpart (59 ± 0.65 U/ml), indicating successful enhancement through the applied mutation techniques. The molecular weight of the inulinase enzyme produced from mutant strain and wild-type was 83 and 86 kDa respectively. These findings suggest potential industrial applications of the improved strain in various biotechnological processes.