Genetic Transformation of Escherichia Coli Cells With Different Degrees of Competence With R-Plasmids

Abstract

Object and research methods. The object of the study was the biomass yield of T. viride KMВ-F-15 depending on the composition of the nutrient medium and the fungistatic activity of the fungal culture filtrate against the phytopathogen Fusarium culmorum IMВ-F-50716. Sucrose, glucose, fructose, maltose, glycerine, green molasses and corn extract at a concentration of 20 g/l were used as carbon sources, and yeast autolysate, corn extract, sodium nitrate, potassium nitrate, ammonium sulphate, ammonium chloride, ammonium nitrate, L-glutamic acid and arginine hydrochloride were used as nitrogen sources in a concentration of 5 g/l. The influence of the composition of the nutrient medium on the growth of Trichoderma was assessed by the yield of dry biomass using the weight method. Fungistatic activity was determined by the level of growth inhibition of F. culmorum on a dense nutrient medium by adding the filtrate of the T. viride culture liquid.Results. It was found that glycerine and green molasses resulted in the highest biomass yield of T. viride КМВ-F-15 (5.0 g/l and 4.9 g/l, respectively). Determination of the fungistatic activity of filtrates of culture liquids obtained from nutrient media with different carbon sources showed that the growth inhibition of F. culmorum IMB-F-50716 compared to the control on 3rd day was in the range of 55.9-70% and reached 94.7-100% on 6th day. However, no significant difference was found between the mean values of the experiments using different carbon sources. The most favourable nitrogen sources were yeast autolysate, in which the yield of dry biomass was 4.4 g/l and ammonium chloride (3.3 g/l). The fungistatic activity of T. viride KMB-F-15 depends on the source of nitrogen nutrition. The highest percentage of phytopathogen growth inhibition was observed when cultivated in a medium with organic nitrogen sources: maize extract, yeast autolysate, or L-glutamic acid (growth inhibition of 48.4-58.7% and 97.8-100% at 3 and 6 days, respectively). Among the inorganic nitrogen sources, ammonium chloride and ammonium sulphate contributed to the manifestation of fungistatic activity (65.9% and 68.8% on the 3rd day, 94% and 88.5% on the 6th day, respectively).Conclusions. For submerged cultivation of T. viride KMВ-F-15 aimed at obtaining a biocontrol agent against phytopathogenic fungi, it is advisable to use glycerol or green syrup as a carbon source and yeast autolysate or ammonium chloride as a nitrogen source, which ensure high biomass yield and a high level of fungistatic activity.