The endochitinase ChiA Btt of Bacillus thuringiensis subsp. tenebrionis DSM- 2803 and its potential use to control the phytopathogen Colletotrichum gloeosporioides

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Norma M. de la Fuente-Salcido1,2, Luz E. Casados-Vázquez2,3, Ada P. García-Pérez1, Uriel E. Barboza-Pérez4, Dennis K. Bideshi5,6, Rubén Salcedo-Hernández2,3, Blanca E. García- Almendarez7 & José E. Barboza-Corona2,3
1 Aniversidad Autónoma de Coahuila, Escuela de Ciencias Biológicas, Torreón, Coahuila, 27104 México
2 Posgrado en Biociencias, División de Ciencias de la Vida, Universidad de Guanajuato Campus Irapuato-Salamanca, Irapuato, Guanajuato, 36500 México
3 Departamento de Alimentos, División de Ciencias de la Vida, Universidad de Guanajuato Campus Irapuato-Salamanca, Irapuato, Guanajuato, 36500, México
4 Tecnológico de Monterrey Campus Querétaro, Epigmenio González 500 Fracc, San Pablo, Querétaro, Qro, 76130 México
5 Department of Natural and Mathematical Sciences, California Baptist University, 8432 Magnolia Avenue, Riverside, 92504 California
6 Department of Entomology, University of California, Riverside, California 92521
7 Universidad Autónoma de Querétaro. DIPA, PROPAC, Facultad de Química, Querétaro, Qro, 76010 México
*josebar@ugto.mx
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 (rChiA Btt, ~74 kDa), was purified by a HiTrap Ni affinity column. The K m of rChiA Btt was 0.847 μmol 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 rChiA74 Btt reduced the radial growth and increased the hyphal density of Colletotrichium  gloeosporioides, the etiological agent of “anthracnose” in plants.

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