Biocontrol of phytopathogens and increased vigor in tomato seeds (Solanum lycopersicum L.) by Bacillus thuringiensis and its bacteriocins


DE LA FUENTE-SALCIDO, Norma Margarita1 *†, QUISTIÁN MARTÍNEZ, Deyanira2 , VALADEZLIRA, Alberto, BARBOZA-CORONA, José Eleazar3 , LAFUENTE-RINCÓN, David Francisco2

1 Dpto. de Bioprospección y Bioprocesos. Facultad de Ciencias Biológicas, Universidad Autónoma de Coahuila.
2 Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León.
3 División Ciencias de la Vida, Universidad de Guanajuato.


Entomopathogenic bacteria such as Bacillus thuringiensis (Bt) and/or its metabolites have been shown to be beneficial for the biocontrol of pests in agricultural crops. In this research, the antifungal potential of five Bt bacteriocins in vitro against F. oxysporum f.sp. lycopersici (Fol) and the effect of bacteriocins and the strains that produce them to stimulate germination (vigor) in tomato seeds (Solanum lycopersicum L. cv. Rio Grande) was determined. The antifungal activity of bacteriocins (100 μL) was determined by well diffusion method on dextrose potato agar (DPA) incubated at 30 oC for 7 days. Germination was evaluated in batches of seed treated by imbibition for 60 minutes at 28 °C in suspensions of Bt cultures (1×107 cells · mL-1 ) or bacteriocin solutions (500 U · mL-1 ), dried at 30-35 °C and allowed to germinate in total darkness at 28 °C for 96 hours. The germination (%) and also the length (cm), the vigor index and the fresh weight (μg) of the tomato shoots were registered and an principal component analysis (ACP) of the obtained results was carried out. The bacteriocins exerted a fungistatic effect on Fol (55-72 %), with greater effectiveness of thuricin H (m). The ACP indicated the greatest effect on germination by the bacteriocin tolworthcin 524 and the producing strain B. thuringiensis subsp. tolworthi, according to the registered value for the maximum vigor index in the tomato shoots. The strains of B. thuringiensis and their bacteriocins have the capacity to act as biocontrol agents of phytopathogens as fungi (Fol) and as germination stimulants in seeds of tomato type Solanum lycopersicum L. cv. Rio Grande.