AUTHOR=Wang Jianrong , Li Xiaoming , Chen Hao , Lin Bilian , Zhao Liangzhong TITLE=Heterologous Expression and Characterization of a High-Efficiency Chitosanase From Bacillus mojavensis SY1 Suitable for Production of Chitosan Oligosaccharides JOURNAL=Frontiers in Microbiology VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.781138 DOI=10.3389/fmicb.2021.781138 ISSN=1664-302X ABSTRACT=

Chitosanase plays an important role in enzymatic production of chitosan oligosaccharides (COSs). The present study describes the gene cloning and high-level expression of a high-efficiency chitosanase from Bacillus mojavensis SY1 (CsnBm). The gene encoding CsnBm was obtained by homologous cloning, ligated to pPICZαA, and transformed into Pichia pastoris X33. A recombinant strain designated X33-C3 with the highest activity was isolated from 120 recombinant colonies. The maximum activity and total protein concentration of recombinant strain X33-C3 were 6,052 U/ml and 3.75 g/l, respectively, which were obtained in fed-batch cultivation in a 50-l bioreactor. The optimal temperature and pH of purified CsnBm were 55°C and 5.5, respectively. Meanwhile, CsnBm was stable from pH 4.0 to 9.0 and 40 to 55°C. The purified CsnBm exhibited high activity toward colloidal chitosan with degrees of deacetylation from 85 to 95%. Furthermore, CsnBm exhibited high efficiency to hydrolyze different concentration of colloidal chitosan to produce COSs. The result of this study not only identifies a high-efficiency chitosanase for preparation of COSs, but also casts some insight into the high-level production of chitosanase in heterologous systems.