Influencia del medio de cultivo, el tipo de inóculo y las condiciones de agitación-aireación en la reproducción de dos cepas de Bacillus thuringiensis (Berl.) en fermentadores de diferentes volúmenes

the behavior of bacillus thuringiensis strain lbt-3 was determinate in fermentation equipment of 30 and 100 l of effective capacity, and for strain lbt-13 by using equipment of 5, 30,100 and 500 l. the parameter obtained by shaker in laboratory level were confirmed when yield of 1-3 x 109 spores and toxins crystal/ml were obtained after 28-32 hours. the two types of inoculums (log cultures and spores) with lbt-3 strain did not show difference in the deferent fermentation scale in relation with the concentration of spores and crystals, but the time of process was lower when log cultures was used. a higher aeration and agitation regimen allowed increase the yield of spores and crystals. in the four scales of fermentation used with lbt-13 strain, the time of the process increase in relation with the volume of fermentation. higher concentration of yields was obtained by using 100 l fermentation equipment and also increased the process time. variations of ph, microbiological characteristics and biomass did not show differences with lbt-13 strain in both 100 and 500 l fermentation equipments. the affectivity of cultures was demonstrated by bioassays.