Kinetics of Growth and Enhanced Sophorolipids Production by Candida bombicola Using a Low-Cost Fermentative Medium

In this study, effect of various parameters on sophorolipid (SL) production by the yeast Candida bombicola was investigated for the enhancing of its production by employing L18 orthogonal array design of experiments. At optimum conditions of sugarcane molasses 50 g l⁻¹, soybean oil 50 g l⁻¹, inoculum size 5% (v/v), temperature 30 °C, inoculum age 2 days, and agitation 200 rpm, the yeast produced almost equal amounts of the product in batch shake flasks and in a 3-l fermentor without any pH control (45 and 47 g l⁻¹, respectively). However, the yield increased to 60 g l⁻¹ in the fermentor under controlled pH environment. Time course of SL production, yeast biomass growth, and utilization of sugarcane molasses and soybean oil at these optimized conditions were fitted to existing kinetic models reported in the literature. Estimated kinetic parameters from these models suggested that conventional medium containing glucose can very well be replaced with the present low-cost fermentative medium.