Statistical Optimisation of Rhamnolipid Production using a Pseudomonas putida Strain Cultivated on Renewable Carbon Sources of Waste Vegetable Oils

Abstract Herein, synthesis of rhamnolipid surfactants was performed using a non-pathogenic Pseudomona s putida strain cultured on a variety of waste frying oils (WFOs) under Taguchi multi-objective optimization design. The effect of substrate types, fermentation setups and incubation time on the biomass concentration, rhamnolipid yield and surface tension of the cultivate media has been investigated. The results demonstrate that the multi-objectives investigation helps to document the optimal limits of the process parameters based on Gray relational analysis. After finding the optimal conditions, a validati on run was performed; therein, the rhamnolipid yield increased from 3.4 to 4.1 g/L; the biomass concentration decreased by 4.84% with an additional surface tension reduction of 2.19% due to an increase of rhamnolipids yield. Overall, soybean WFO was observed to be a preferred substrate for P. putida strain both under Taguchi design and the validation run. The present study proposes a low total of runs and optimum product yield under the Taguchi based multi-objective optimization.