title: Native soil bacteria isolates in Mexico exhibit a promising antagonistic effect against Fusarium oxysporum f. sp. radicis-lycopersici.
abstract: Sinaloa state accounts for 23% of Mexico's tomato production. One constraint on this important crop is the Fusarium crown and root rot, caused by Fusarium oxysporum f. sp. radicis-lycopersici, which has been reported to reduce crop yield by up to 50%. In this study, we set out to identify bacterial populations which could be used to control this disease through natural antagonism. Five tomato rhizospheric soil samples were collected, dried for 1-week, and homogenized. Sub-samples were used to prepare an aqueous solution used to isolate microorganisms in pure cultures. Organisms were purified and grown separately, and used to generate a collection of 705 bacterial isolates. Thirty-four percent from this bank (254 strains) was screened against Forl, finding 27 bacteria displaying in vitro Forl growth inhibition levels from 5% to 60%. These isolates belonged to the genus Bacillus and their 16Sr DNA sequences showed that they are closely related to seven species and they were putatively designated as: B. subtilis, B. cereus, B. amyloliquefaciens, B. licheniformis, B. thuringiensis, B. megaterium, and B. pumilus. One isolate belonged to the genus Acinetobacter. Two B. subtilis isolates (144 and 151) and one B. cereus isolate (171) showed the best antagonistic potential against FCRRT when evaluated on seedlings. Plate and activity assays indicate that these isolates include a diverse repertoire of functional antagonistic traits that might explain their ability to control FCRRT. Moreover, bacteria showed partial hemolytic activity, and future research will be directed at ensuring that their application will be not harmful for humans and effective against Forl in greenhouse or field conditions.
authors: Departamento de Biotecnología Agrícola, Instituto Politécnico Nacional, CIIDIR-Sinaloa, Guasave, Sinaloa, Mexico.
authors: Jesús Damián
authors: JD
authors: Cordero-Ramírez
authors: Raquel
authors: R
authors: López-Rivera
authors: Alejandro Miguel
authors: AM
authors: Figueroa-Lopez
authors: María Elena
authors: ME
authors: Mancera-López
authors: Juan Carlos
authors: JC
authors: Martínez-Álvarez
authors: Miguel Ángel
authors: MÁ
authors: Apodaca-Sánchez
authors: Ignacio Eduardo
authors: IE
authors: Maldonado-Mendoza
mesh_terms: D000150:Acinetobacter / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000898:Antibiosis; D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D001409:Bacillus cereus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D001410:Bacillus megaterium / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D001412:Bacillus subtilis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001413:Bacillus thuringiensis / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D005670:Fusarium / Q000254:growth & development*; D018551:Solanum lycopersicum / Q000382:microbiology; D008800:Mexico; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D012988:Soil Microbiology
keywords: Bacterial antagonism; FCRRT; Forl; Microorganism collection; Native bacteria