Enhancing the enzymatic saccharification of bamboo shoot shell by sequential biological pretreatment with Galactomyces sp. CCZU11-1 and deep eutectic solvent extraction

In this study, sequential biological pretreatment (BP) with Galactomyces sp. CCZU11-1 at 30 °C for 3 days and deep eutectic solvent (DES) choline chloride: oxalic acid (ChCl:OA, 1 mol/2 mol) extraction at 120 °C for 1.5 h was used for pretreating BSS. It was found that combination pretreatment could effectively remove xylan and lignin for enhancing enzymatic saccharification. The reducing sugars and glucose from the hydrolysis of 100 g/L pretreated BSS with complexed cellulases of Galactomyces sp. CCZU11-1 were obtained in the yields of 81.0% and 74.1%, respectively. The BSS-hydrolyzates had no inhibitory effects on the lipid-accumulating microorganism Bacillus sp. CCZU11-1, and the cell mass and TAG accumulation were 4.8 g CDW/L and 2.2 g TAG/L, respectively. Fatty acids including palmitic acid (C16:0; 25.3%), palmitoleic acid (C16:1; 24.4%), stearic acid (C18:0; 15.1%), and oleic acid (C18:1; 21.6%) were accumulated in cells. Clearly, this combination pretreatment has high potential application in future.