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摘要
Chitosanase plays an important role on enzymatic preparation of chitosan oligosaccharides (COSs) with different degree of polymerization. High-level expression of chitosanase will provide foundation for its industrial application. Herein, a gene encoding chitosanase (bacsn46) from Bacillus atrophaeus Rkl was cloned and analyzed. The chitosanase from Bacillus atrophaeus Rkl (BaCsn46) was overexpressed by combining codon optimization and co-expression of helper gene. In addition, the biochemical properties of BaCsn46 were characterized. The open reading frame of bacsn46 is 825 bp in length, which encodes a protein of 274 amino acid residues, including a potential signal sequence of 32 amino acid residues. The maximum activity was 7 356 U/mL and total protein content 5.95 g/L, which were obtained in fed-batch cultivation in a 7 L bioreactor. The optimal condition for purified BaCsn46 were 60 °C and pH 6.0. The activity of purified BaCsn46 was stimulated by Mg2+ and Mn2+, respectively. The smallest and most favorable substrates of purified BaCsn46 were chitotetraose and colloidal chitosan with degrees of deacetylation of 95%, respectively. Furthermore, the purified BaCsn46 exhibited high efficiency to hydrolyze colloidal chitosan to prepare COSs with different degree of polymerization. ? 2023 China National Research Institute of Food and Fermentation Industries Co. Ltd.
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