| Autor: |
Castillo BM; El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico. bmoreno@ecosur.edu.mx., Dunn MF; Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico., Navarro KG; El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico., Meléndez FH; El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico., Ortiz MH; Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico., Guevara SE; Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico., Palacios GH; El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico. ghuerta@ecosur.mx. |
| Abstrakt: |
The tropical and mycoparasite strain Streptomyces galilaeus CFFSUR-B12 was evaluated as an antagonist of Mycosphaerella fijiensis Morelet, causal agent of the Black Sigatoka Disease (BSD) of banana. On zymograms of CFFSUR-B12 culture supernatants, we detected four chitinases of approximately 32 kDa (Chi32), 20 kDa (Chi20), and two with masses well over 170 kDa (ChiU) that showed little migration during denaturing electrophoresis at different concentrations of polyacrylamide. The thymol-sulphuric acid assay showed that the ChiU were glycosylated chitinases. Moreover, matrix assisted laser desorption ionization time-of-flight MS analysis revealed that the ChiU are the same protein and identical to a family 18 chitinase from Streptomyces sp. S4 (gi|498328075). Chi32 was similar to an extracellular protein from Streptomyces albus J1074 (gi|478687481) and Chi20 was non-significantly similar to chitinases from five different strains of Streptomyces (P > 0.05). Subsequently, Chi32 and Chi20 were partially purified by anion exchange and hydrophobic interaction chromatography and tested against M. fijiensis. Chitinases failed to inhibit ascospore germination, but inhibited up to 35 and 62% of germ tube elongation and mycelial growth, respectively. We found that crude culture supernatant and living cells of S. galilaeus CFFSUR-B12 were the most effective in inhibiting M. fijiensis and are potential biocontrol agents of BSD. |
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