Optimization of ß-Galactosidase production in stirred tank bioreactor using Kluyveromyces lactis NRRL Y-8279

This paper investigates the production and optimization of ß-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in stirred tank bioreactor. Response surface methodology was used to investigate the effects of fermentation parameters on ß-galactosidase enzyme production. Maximum specific enzyme activity of 4,622.7 U/g was obtained at the optimum levels of process variables (aeration rate 2.21 vvm, agitation speed 173.4 rpm, initial sugar concentration 33.8 g/L, incubation time 24.0 hr). The optimum temperature and pH of the ß-galactosidase enzyme produced under optimized conditions were 37°C and pH 7.0, respectively. The enzyme was stable over a pH range of 6.0-7.5 and a temperature range of 25-37°C. The Km and Vmax values for O-nitrophenol-ß-D-galactopyranoside (ONPG) were 1.20 mM and 1,000 µmol/min·mg protein, respectively. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in ß-galactosidase enzyme production. Hence, this study fulfills the lack of using mathematical and statistical techniques in optimizing the ß-galactosidase enzyme production in stirred tank bioreactor. © The Korean Society of Food Science and Technology.