DESIGN AND EVALUATION OF LIQUID MEDIA FOR THE PRODUCTION OF BLASTOSPORES OF Beauveria bassiana

Abstract

Background. The nitrogen source in a liquid culture medium for the propagation of entomopathogenic fungi is considered an essential element in fermentation, however, it is one of the most expensive, which makes the search for alternative sources of this nutrient important. Objective. This research compared the production of blastospores obtained by designing different culture media for the GHA strain of Beauveria bassiana based on the nitrogen source used. Methodology. Six media were designed in liquid form, made with various nitrogen sources (sesame flour, amaranth flour, canary seed flour, linseed flour, peanut pericarp flour, oatmeal) with glucose corn as a carbon source for all of them. Additionally, the yield of blastospores obtained at different incubation times, the pH and the viability of the post-fermentation propagules were evaluated. Results. The M8 medium made with peptone and yeast extract as nitrogen sources was the one that obtained the highest concentration with 1.28 × 109 blastospores / mL at 168 hours of incubation. Regarding the fermentation parameters evaluated, the pH ranged between 5.1- 5.5 and the determination of this parameter did not present significant difference with respect to the culture medium used or the day on which it was determined (p ≥ 0.05) while post-fermentation viability was determined. In two solid media, and according to the results in potato dextrose agar the viability ranged between 31-90% on average while in water agar it was 25-90%, the determination of this parameter did not present significant difference with respect to the medium of culture for production of blastospores or to the solid medium in which it was determined (p ≥ 0.05). Implications. The alternate nitrogen sources used did not significantly increase the production of blastospores compared to conventional sources such as peptone and yeast extract, which in a synergistic effect did manage to enhance the production of blastospores. Conclusion. The use of yeast extract and casein peptone in conjunction can increase the yield of blastsopores in a liquid culture medium.