RECOMBINANT EXTRACELLULAR CHITINASE FROM BREVIBACILLUS LATEROSPORUS FOR BIOLOGICAL CONTROL AND OTHER INDUSTRIAL USES

摘要

The present invention discloses a recombinant, modified extracellular chitinase having an amino acid sequence set forth in SEQ ID NO.4 or SEQ ID NO.5. The recombinant, modified chitinase is derived by inserting two-point mutations at positions 661 and 2158 in the native chitinase gene of Brevibacillus laterosporus LAK 1210 which results in amino acid substitution of tyrosine (Y) residue with histidine (H) at positions 221 and 720. The modified chitinase exhibits both exochitinase and endochitinase activity. The recombinant, modified enzyme is thermoactive with a temperature optimum of 55-60° C. and high thermostability (Tm of 66.7° C.), functions in a broad pH range (pH 3.0-11.0) having a pH optimum of 9.0 and also exhibits improved solubility and enhanced efficacy for control of insects and phytopathogenic fungi. The invention further provides improved methods for large scale production of recombinant modified chitinase and rapid, cost-effective purification method by chitin-adsorption affinity chromatography using powdered crustacean shells.