Response surface methodology for optimization of media components for production of lipase from Bacillus Subtilis KUBT4

Abstract

Lipases belong to a class of triacylglycerol hydrolases possessing a lot of potential applications due to their various physical properties. Most of the lipase producers are extracellular in nature are produced using solid-state fermentation and submerged fermentation methods. The fungal, mycelial, and the yeast lipases are produced using various solid substrates through solid-state fermentation method. This method is cost effective and hence widely used in industries to produce lipase using fungi. Whereas lipases from bacteria, were produced using submerged fermentation. The optimization of media is a main requirement for increasing the quantitative yield by overproduction of enzymes. The optimization of media is a main requirement for increasing the quantitative yield by overproduction of enzymes. Different parameters such as pH, temperature, agitation speed, inoculum size, incubation time, carbon and nitrogen sources have been of great importance for the researchers to design economical media. The OFAT is a one-dimensional approach that is laborious and time-consuming and does not consider interactions between the factors. The limitations of OFAT method can be reduced by employing techniques such as Plackett-Burman design (PBD) and response surface methodology (RSM). The PBD is a method to screen the variables that influence the production and remove the non-significant factors to attain a lesser and manageable set of factors. Subsequently, the chosen significant factors are optimized by RSM that assists to study the interactions of different factors. The RSM comprises of central composite design (CCD) to fit a second-order polynomial equation. In this study, the effect of temperature, tryptone, inoculum size and incubation time on the lipase production were analysed by Plackett-Burman design screening experiments. The experiments were designed using four variable Central composite design of RSM using Design Expert software. This model predicted optimal activity of lipase of 58.53 U/mL at 1.5% tryptone, 10 mL inoculum size, incubated for 48 hrs at 34℃. This experiment was further validated and optimal activity of lipase of 57.85 U/mL was observed. Thus, RSM model enhanced the production of lipase and can be applied for the maximum yield of lipase.