PRODUCCIÓN Y EVALUACIÓN DE Bacillus subtilis Y Trichoderma harzianum PARA EL CONTROL DE LA SARNA DE LA PAPA “Streptomyces spp.”

Abstract

The Potato is one of the main vegetables in Mexico; their cultivation is one of the most important in the food industry. Pests and diseases cause significant losses in yield and quality of this product, among the diseases the most common scab caused by (Streptomyces spp.) is important in the region. The disease affect severely the quality of the tuber, reducing seriously its commercial value. Streptomyces spp infect the tuber potatoes, and can also be transmitted through of the seed tubers. The objective of this work was: The mass production of Bacillus subtilis and Trichoderma harzianum, determining the key physico-chemical factors, using the liquid and solid medium for their propagation. The antagonistic effect against Streptomyces spp.. in vitro was too assessed, as well as its effectiveness to the greenhouse level. The result for in vitro antagonism of B. subtilis against Streptomyces spp., showed a positive effect to inhibit the development of the pathogen, while the in vitro bioassay of T. harzianum against Streptomyces spp. showed also positive antagonistic effects, inhibiting the development of the pathogen to the 72 h. B. subtilis against T. harzianum had negative antagonistic effect among. With regard to the production of Bacillus subtilis and Trichoderma harzianum used a synthetic medium (MM)* allowed good growth of these microorganisms, and the key physic-chemical factors for B. subtilis were: 200 RPM agitation, temperature 30 0C and pH 7, producing a high level of biomass, 14.20 g/l of biomass and a concentration of 2.9x108 UFC/ml. The liquid fermentation of T. harzianum was successful with a synthetic medium (MM)** designed for growth fungus, and the physico-chemical factors were; agitation 150 RPM, temperature 28 0c and pH 5.5, resulting in the collection of biological material (mycelium and chlamydospores); after in solid fermentation were obtained 1.3 x 1010 esp/ml with 98% of spore viability.