Resumen
- The genre Azotobacter sp. represents a group of bacteria that can exert positive effects on the stimulation and plant growth promotion in multiples crops, and additionally possess the capacity of asymbiotic nitrogen fixation. In the present work, the biomass production of two strains of A. chroococcum (named Ac1 and Ac10) using liquid fermentation for the further production of a biofertilizer was evaluated. For this, a liquid culture medium previosly optimized (coded as MBR) was used for a liquid fermentation process in a Infors model Minifors laboratoy bioreactor with a capacity of 3.5L, initially a batch type strategy was applied for generate a baseline for this research. In order to increase process efficiency, the effect of reduce the stirring speed was evaluated; therefore, when a stirring speed of 200 rpm was evaluated, while maintaining the air flow and the culture time, under conditions of fed-batch type fermentation, an increase in the cell concentration was observed from 1.54E9 CFU/mL to 4.21E9 CFU/mL for Ac1 strain; an increase of 2.21E9 CFU/mL to 3.92E9 CFU/mL for Ac10 strain; with a simultaneous reduction in energy consumption of 96.7%. Additionally, this increase in cell concentration for both strains also promote a rising of parameters of efficiency, biomass concentration and fermentation productivity, about two times in comparison with the values determined at baseline.