Production of cellulolytic enzymes by Myceliophthora thermophila and their applicability in saccharification of rice straw

Optimization of cellulase production by Myceliophthora thermophila BJTLRMDU3 was studied in solid state fermentation. Sequential use of Plackett-Burman and response surface methodology (RSM) resulted in the production of 98.81, 243.19, and 316.48 U/g dry moldy residue (DMR) of FPase, CMCase, and beta-glucosidase, respectively. Statistical optimization has resulted in more than 4.0-fold increase in the production of cellulases. Optimization of saccharification of untreated and pretreated rice straw was carried out by cellulolytic enzymes of thermophilic mold M. thermophila. The liberation of reducing sugars was higher using fungal cellulases in ammonia-pretreated rice straw as compared with untreated biomass. Maximum liberation of reducing sugars was attained at 60 degrees C (224.24 mg/g substrate) and pH 5.0 (246.33 mg/g substrate) after an incubation time of 24 h (345.61 mg/g substrate) using enzyme dose of 20 U/g in ammonia-pretreated rice straw. Supplementation of xylanase further enhanced the saccharification (488.78 mg/g substrate) of pretreated rice straw. Analysis using high-performance liquid chromatography (HPLC) indicated the presence of various monomeric and oligomeric sugars in the enzymatic hydrolysate of pretreated rice straw. Both, Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) revealed the structural changes in rice straw after ammonia pretreatment.

Automated summary

The optimization of cellulase production and saccharification of rice straw by Myceliophthora thermophila BJTLRMDU3 in solid state fermentation was studied. Sequential use of Plackett-Burman and response surface methodology resulted in a significant increase in cellulase production. The saccharification of ammonia-pretreated rice straw was higher compared to untreated biomass. The addition of xylanase further enhanced the saccharification of pretreated rice straw, resulting in the liberation of reducing sugars.