Multi-objective based superimposed optimization method forenhancement ofL-glutaminase production byBacillus subtilisRSP-GLU

Abstract

L-Glutaminase (L-glutamine amidohydrolase, EC 3.5.1.2) is a deamiding enzyme that has current focus on a therapeutic po-tentials and flavor enhancement agent in food industry. It was noticed that the amidase production was depended on the bacterialgrowth. However, the enhancement of bacterial growth by other substrates suppress the secretion ofL-glutaminase. Governing thegrowth as well as amidase production is challenging task. In this study a multi-objective based superimposed optimization methodwas employed to control the biomass as well as to enhance the production ofL-glutaminase. Various parameters such as volume ofmedium, pH, incubation temperature, inoculum level,L-glutamine concentration and rpm were optimized. The interactive influenceof these parameters with their effect on enzyme and biomass production was analyzed using fractional factorial central compositedesign (FFCCD). The coefficient of determination (R2) was calculated as 0.9862 and 0.9513 forL-glutaminase and biomassproduction respectively. Overlay graphs were plotted by superimposing the contours for the various response surfaces of biomassand enzyme production. Based on superimposing method the cultural conditions obtained was volume of media 85 mL, temperature37C, pH 7.24, inoculum concentration 2.47 mL,L-glutaminase concentration 1.01 g/L and agitation speed of 109 rpm. At theseconditions 225 U/mLL-glutaminase and 0.79 g/L biomass were obtained. The current study provides a good description forbalanced optimization of fermentation process of multi response or objective systems by using FFCCD method.