Optimization of cellulase complex formulation for peashrub biomass hydrolysis.

To improve efficiency and reduce cost, solid state simultaneous saccharification and fermentation of peashrub woody biomass was investigated under anaerobic conditions at 50 degrees C, with a cellulase-inoculant mixture consisting of Trichoderma koningii cellulase, Aspergillus niger cellulase, and Lactobacillus. Experimental formulations were prepared according to uniform prescription design principles. By crude protein, crude fiber models constructed using multivariate regression in SPSS and solutions analysis through unconstrained mathematical optimization in Microsoft Excel, it was clearly revealed that low pH value (3.8) from lactic acid accumulation produced by Lactobacillus would ultimately limit enzymatic hydrolysis during long-term fermentation (30 days). It was shown that a cellulase complex with filter paper cellulase/carboxymethyl cellulase/cotton lyase/beta-glucosidase/pectinase of activity ratios of 0.6:1:0.3:1:2.6 could effectively break peashrub cell wall structure by biodegradation of easily digested components and, then, release cellular contents to improve crude protein content. Thus, the enzymatic hydrolysis of peashrub biomass by the optimized cellulase complex could improve crude protein content by 45.3% (from 8.45 to 12.28%), although it only biodegraded about 10.90% of the crude fiber (from 44.45 to 40.08%).