The endochitinase ChiA Btt of <i>Bacillus thuringiensis</i> subsp. <i>tenebrionis </i><scp>DSM</scp>‐2803 and its potential use to control the phytopathogen <i>Colletotrichum gloeosporioides</i>

Abstract

Abstract Bacillus thuringiensis subsp. tenebrionis DSM ‐2803 has been studied extensively and spore/crystal mixtures of this strain are used widely in commercial products to control coleopteran pests. The endochitinase chiA Btt gene of B. thuringiensis subsp. tenebrionis DSM ‐2803 was cloned and expressed in Escherichia coli . The recombinant 6x‐histidine tagged protein ( rC hiA Btt, ~74 kD a), was purified by a HiTrap Ni affinity column. The K m of rC hiA Btt was 0.847 μ mol L −1 and its optimal activity occurred at pH 7 and ~40°C. Most divalent cations reduced endochitinase activity but only Hg +2 abolished activity of the enzyme. We report for the first time the characterization of a chitinase synthesized by B. thuringiensis subsp. tenebrionis DSM ‐2803, and show that the purified rC hiA74 Btt reduced the radial growth and increased the hyphal density of Colletotrichium gloeosporioides, the etiological agent of “anthracnose” in plants.