title: Antifungal performance of extracellular chitinases and culture supernatants of Streptomyces galilaeus CFFSUR-B12 against Mycosphaerella fijiensis Morelet.
abstract: 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.
authors.affiliation: El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico. bmoreno@ecosur.edu.mx.
authors.forename: Benjamín Moreno
authors.identifier: http://orcid.org/0000-0001-6871-5377
authors.initials: BM
authors.lastname: Castillo
authors.affiliation: Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Dunn
authors.affiliation: El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico.
authors.forename: Karina Guillén
authors.initials: KG
authors.lastname: Navarro
authors.affiliation: El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico.
authors.forename: Francisco Holguín
authors.initials: FH
authors.lastname: Meléndez
authors.affiliation: Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: Magdalena Hernández
authors.initials: MH
authors.lastname: Ortiz
authors.affiliation: Centro de Ciencias Genómicas, Universidad Autónoma de México (UNAM), Campus Morelos, Av. Universidad s/n Col. Chamilpa, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: Sergio Encarnación
authors.initials: SE
authors.lastname: Guevara
authors.affiliation: El Colegio de la Frontera Sur (ECOSUR), Carr. Antiguo Aeropuerto km. 2.5, Apartado Postal 36, 30700, Tapachula, Chiapas, Mexico. ghuerta@ecosur.mx.
authors.forename: Graciela Huerta
authors.initials: GH
authors.lastname: Palacios
mesh_terms: D000898:Antibiosis; D000935:Antifungal Agents / Q000378:metabolism*; D001203:Ascomycota / Q000187:drug effects* / Q000254:growth & development*; D002688:Chitinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002853:Chromatography, Liquid; D004586:Electrophoresis; D008970:Molecular Weight; D028521:Musa / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D002688:Chitinases
keywords: Chitinases; Culture supernatant; Mycosphaerella fijiensis; Streptomyces galilaeus