Cerein 8A production in soybean protein using response surface methodology

In this work a 23 factorial design was performed with the aim of optimizing the bacteriocin (cerein 8A) production by Bacillus cereus 8A, using response surface methodology (RSM). The bacteriocin production was first tested on different substrates, like soybean meal, soybean protein, fish meal, industrial fibrous soybean residue and cheese whey. Soybean protein was the selected medium to test the effect of three variables (temperature, initial pH and soybean protein concentration) by RSM. Statistical analysis of results showed that, in the range studied, the three variables have a significant effect on cerein 8A production. Response-surface data showed maximum bacteriocin production at initial pH between 6.5 and 9.0, temperature between 22 and 34 °C and soybean protein concentration higher than 20 g l−1. It was not possible to determine a relation between bacteriocin production and optimal conditions for bacterial growth in terms of pH and temperature, although increased bacteriocin yields and bacterial growth were obtained with higher soybean protein concentration.