Kinetic modeling of biosurfactant production by Bacillus subtilis N3-1P using brewery waste

Abstract

Abstract Costs associated with production of favorable biologically produced surfactants continue to be a significant obstacle to large scale application. Using industrial wastes and by-products as substrate and optimization of cultural conditions are two strategies of producing biosurfactants with a reasonable price. Also, modeling the biosurfactant production bioprocess improves the commercial design and monitoring of biomass growth, biosurfactant production, and substrate utilization. In this study, the indigenous Bacillus subtilis N3-1P strain and a local brewery waste as the carbon source were used to produce a biosurfactant. The batch cultivation was performed under the optimum conditions. Models describing the biomass growth, biosurfactant production, and substrate utilization were developed by fitting the experimental data to the logistic, Contois and Luedeking-Piret models using MATLAB software and regression analysis. The kinetic parameters including the maximum specific growth rates (µ max), the Contois constant (K), parameters of the Luedeking-Piret modelswere calculated. Yields including Y X/S , and Y P/X were found to be 0.143 gX/gS, and 0.188 gP/gX, respectively. The experimental and predicted model showed good agreement. The developed models are a key step in designing reactors for scale up of biosurfactant production.