Effect of -mannanase domain from Trichoderma reesei on its biochemical characters and synergistic hydrolysis of sugarcane bagasse

BACKGROUND-mannanase is a key enzyme for hydrolyzing mannan, a major constituent of hemicellulose, which is the second most abundant polysaccharide in nature. Different structural domains greatly affect its biochemical characters and catalytic efficiency. However, the effects of linker and carbohydrate-binding module (CBM) on -mannanase from Trichoderma reesei (Man1) have not yet been fully described. The present study aimed to determine the influence of different domains on the expression efficiency, biochemical characteristics and hemicellulosic deconstruction of Man1. RESULTSThe expression efficiency was improved after truncating CBM. Activities of Man1 and Man1CBM (CBM) in the culture supernatant after 168h of induction were 34.5 and 42.9IU mL(-1), although a value of only 0.36IU mL(-1) was detected for Man1LCBM (lacking CBM and linker). Man1 showed higher thermostability than Man1CBM at low temperature, whereas Man1CBM had a higher specificity for galactomannan (K-m=2.5mg mL(-1)) than Man1 (K-m=4.0mg mL(-1)). Both Man1 and Man1CBM could synergistically improve the hydrolysis of cellulose, galactomannan and pretreated sugarcane bagasse, with a 10-30% improvement of the reducing sugar yield. CONCLUSIONLinker and CBM domains were vital for mannanase activity and expression efficiency. CBM affected the thermostability and adsorption ability of Man1. The results obtained in the present study should help guide the rational design and directional modification of Man with respect to improving its catalytic efficiency. (c) 2017 Society of Chemical Industry