In this work three fermenters were characterized: New Brunswick M-19 of 14 liters, Biocontroller Applikon 1035 of 7 liters and New Brunswick Bioflo III of 7 liters, determining the volumetric coefficient oxygen transfer (KLa), gas hold up (GH) and the mixing time (tM). The fermenter New Brunswick Bioflo III had the best values with a ratio of diameter of the impeller/ vessel (DI/DT) of 0.43, KLa = 9.5-208 h -1 and tM = 1.0-3.0 s, so it was selected for the production of blastospores of Beauveria bassiana, using molasses as carbon source. We studied the mixing conditions, using different combinations of impellers, type Rushton, Lightnin and Maxflo under a factorial experimental design 3 2 . The propagation time was of 4 days, working volume 4l, 10% inoculum (1x10 6 blastospores/ml), temperature 30°C, agitation of 400-500 rpm, aeration 0.5-1.0 vvm, and pH of 5.4. The fungus growth better using a combination of impellers Rushton-Maxflo at 400 rpm and 1.0 vvm (F = 10.324, p ≤ 0.0123) (LSD = 0.585) obtaining a concentration of 1.2x10