Optimization of cultivation conditions for the production of phytate-degrading enzymes by Enterobacter sakazakii ASUIA279 isolated from Malaysian maize root

The production of extracellular phytase by Enterobacter sakazakii ASUIA279 was optimized using response surface methodology with full-factorial faced centred central composite design. Two sets of experiments were carried out to optimize the five most profound factors of the cultivation conditions in order to maximize phytase production. Incubation temperature, initial pH of the media and percentage of rice bran supplemented into the media were optimized in Erlenmeyer flasks while agitation and aeration effect were controlled in a bioreactor. This design reduced the number of actual experiment performed to optimize phytase production and allowed the study of possible interactions among the factors. In the first set of experiments linear and quadratic effect of initial pH was determined to be the most significant factor affecting phytase production. In the bioreactor both linear effects of agitation and aeration, were identified to be highly significant (> 99 %) in respect to phytase yields. Optimal phytase production was observed at a incubation temperature of 39.7 ºC, an initial pH of 7.1, supplementation with 13.6 % rice bran , 320 rpm of agitation and 0 vvm of aeration.