Optimization of cultural conditions using response surface methodology versus artificial neural network and modeling of l-glutaminase production by Bacillus cereus MTCC 1305

Abstract

Response surface methodology and artificial neural network were used to optimize cultural conditions of l-glutaminase production from Bacillus cereus MTCC 1305. ANN model was superior to RSM model with higher value of coefficient of determination (99.97ANN>97.78RSM), predicted distribution coefficient (0.9992ANN>0.896RSM) and lower value of absolute average deviation (1.17%ANN<18.47%RSM). Optimum cultural conditions predicted by ANN were pH (7.5), fermentation time (40h), temperature (34°C), inoculum size (2%), inoculum age (10h) and agitation speed (175rpm) with a maximum predicted production of l-glutaminase 666.97U/l which was close to experimental production of l-glutaminase 667.23U/l at simulated optimum cultural condition. The production of l-glutaminase was enhanced by 1.58-fold after optimization of cultural conditions. Simple kinetic models were developed using Logistic equation for cell growth, Luedeking Piret equation for l-glutaminase production and modified Luedeking Piret equation for glucose utilization indicating that l-glutaminase fermentation is non growth associated process. © 2013 Elsevier Ltd.