Biochemical characterization of a GH19 chitinase from Streptomyces alfalfae and its applications in crystalline chitin conversion and biocontrol

• Published in: International journal of biological macromolecules Vol. 167; pp. 193 - 201
• Main Authors: Lv, Chenyin, Gu, Tianyan, Ma, Rui, Yao, Wei, Huang, Yuyang, Gu, Jingang, Zhao, Guogang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2021
• Subjects: Amino Acid Sequence; Anti-fungi; Antifungal Agents - chemistry; Antifungal Agents - pharmacology; Biodegradation, Environmental; Catalysis; Chemical Phenomena; Chitin - chemistry; Chitinases - chemistry; Chitinases - genetics; Chitinases - isolation & purification; Cloning, Molecular; Enzymatic conversion; Enzyme Activation; Gene Expression; GH19 chitinase; Hydrolysis; Models, Molecular; Protein Conformation; Recombinant Proteins; Sequence Analysis, DNA; Streptomyces - enzymology; Streptomyces - genetics; Substrate Specificity; Anti-fungi; Enzymatic conversion; GH19 chitinase
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.11.178

Chitinases play crucial roles in enzymatic conversion of chitin and biocontrol of phytopathogenic fungi. Herein, a chitinase of glycoside hydrolase (GH) family 19, SaChiB, was cloned from Streptomyces alfalfae ACCC 40021 and expressed in Escherichia coli BL21(DE3). The purified SaChiB displayed maximal activities at 45 °C and pH 8.0, and showed good stability up to 55 °C and in the range of pH 4.0–11.0, respectively. It exhibited substrate specificity towards chitin and chitooligosaccharides (degree of polymerization 3–6) with the endo-cleavage manner. In combination with the N-acetyl hexosaminidase SaHEX, it yielded a conversion rate of 95.2% from chitin powder to N-acetyl-D-glucosamine in 8 h and a product purity of >98.5%. Furthermore, the enzyme strongly inhibited the growth of tested pathogenic fungi. These results indicated that SaChiB has the great potential for applications in the conversion of raw chitinous waste in industries as well as the biocontrol of fungal diseases in agriculture. [Display omitted]