Cellulolytic enzymes from Penicillium funiculosum MRJ-16 mutants and their application in the hydrolysis of pretreated rice straw

The viability of 2G ethanol depends on low-cost enzymes and efficient biomass hydrolysis. The quality of cellulolytic enzymes also plays a crucial role. The cost of enzyme in 2G ethanol process is up to 20%. In view of the urgency of biofuels and demand for cellulolytic enzymes, good hyper-cellulolytic strains are needed. The present study aims to further improve the available fungal mutant. To improve fungal strain, protoplasts of previously developed Penicillium funiculosum MRJ-16 strain were subjected to UV and chemical mutagen. Isolated mutants were evaluated for their ability to secrete cellulases and xylanases using glucose or cellulose or pre-treated rice straw as a substrate. At 7.5 L reactor scale, one of the mutant MPA-F9 produces 7.99 FPU/ml enzyme activity. Mutants were also assessed for their ability to hydrolyze acid-pre-treated rice straw at 15% total solid loading. The MPA-F9 mutant produced a maximum total sugar of 70.5 g/L, compared to 62.9 g/L for its parent strain MRJ-16. Secretome analysis by LC-MS/MS revealed that MPA-F9 has a few other secretory proteins, including glucanase, swollenin, and low levels of dipeptidyl peptidase. This study shows that the mutant strain is a promising candidate for cellulolytic enzyme production, aiding cost-effective conversion of biomass to sugars.