Efficient conversion of α-chitin by multi-modular chitinase from Chitiniphilus shinanonensis with KOH and KOH-urea pretreatment

Abstract

Enzymatic conversion of α-chitin to high-value chitooligosaccharides (COS) was up to 7.2 % by a slow-acting endo-chitinase (uni-modular) after KOH or KOH-urea pretreatment. Here, we report a better source for efficient conversion of α-chitin, with KOH/KOH-urea (20K2 or 20KU2) pretreatment, by a multi-modular chitinase (CsChiG) from Chitiniphilus shinanonensis. The CsChiG and its catalytic domain (Cat-CsChiG) converted 20KU2 substrate to soluble COS with an efficiency of 43.1 % and 11.8 %, respectively. Deletion of the chitin binding domain has reduced the conversion of untreated and colloidal chitin substrates by 4−5 folds, and for 20K2 and 20KU2 substrates it was only two folds decrease. A combination of KOH or KOH-urea pretreatment, followed by enzymatic hydrolysis with multi-modular chitinases, thus appears a promising approach to convert the abundantly available chitin to highly useful COS.