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The study investigated the feasibility of co-production of nanocellulose crystal (CNC) and ethanol using the bleached pine kraft pulp (BPKP) as a substrate by enzymatic hydrolysis. An engineering strain Penicillum oxalicum cEES-XM was constructed to produce suitable cellulase used in enzymatic hydrolysis of BPKP for preparing CNC. The cellulase from Trichoderma reesei SCB18 was used for simultaneous saccharification and fermentation of residues and hydrolysates from enzymatic hydrolysis for producing ethanol. The result showed that the CNC yield reached 7.35 % (w/w) by hydrolysis at 10 % solid content, and the final ethanol concentration was 13.27 mg/mL in fermentation liquor. Using SEM, XRD, TGA, and DLS methods, the characteristics of CNC including, morphology, crystallinity, thermal stability and particle size distribution, were also examined. This work provided a reference for realizing high-efficient application of cellulose in the pulp.

In this study, three endoglucanases (EGs; Cel7B, Cel5B, and Cel12A), one cellobiohydrolase (CBH), and two auxiliary proteins (swollenin: SWO1 and SWO4) were used to hydrolyze microcrystalline cellulose (MCC) for cellulose nanocrystal (CNC) preparation. The mixture experiment of the three EGs showed that high CNC yield was obtained when the ratio of Cel7B and Cel5B is 1:1.11 (protein weight). Moreover, the addition of CBH (1 mg/g) and SWO1 from Trichoderma reesei effectively increased the yield of CNC. On the basis of the results, the cellulase-producing strain of Penicillium oxalicum M12 was engineered to improve its cellulase system. An engineered strain of cEES performed well in CNC preparation. CNC with a yield of 11.79 % and a crystallinity of 83.85 % were produced using the crude enzyme from cEES as a means to hydrolyze MCC, and the size and shape of CNC were uniform and fusiform.