Improved Production of Bacillus thuringiensis by Intermittent Fed-Batch Culture with Total Cell Retention

Abstract

Intermittent fed-batch culture with total cell retention was evaluated during Bacillus thuringiensis serovar. kurstaki fermentations aiming to enhance biomass and spore concentration yields while maintaining toxicity. This method is derived from the already reported intermittent fed-batch culture and utilized a tangential flow filtration system for cell retention. After 4 pulses, we obtained a biomass of 74.36 g·L-1 and this biomass displayed a half lethal concentration towards neonate Spodoptera frugiperda larvae of 40.53 ng·cm-2, and spore concentration of 4.6 x 1014 CFU mL-1. On the other hand, volumetric productivity was increased seven-fold compared to batch fermentation. Interestingly, we are not aware of higher spore concentrations reported to date for B. thuringiensis cultures.