Utilization of Renewable Feedstocks for the Production of Sophorolipids by Native Yeasts from Brazilian Cerrado Biome

One of the main constraints of sophorolipid (SL) microbial production is the substrate-associated costs and the lower productivity compared to synthetic surfactants. Nevertheless, SLs have found their potential in multiple markets, including agriculture due to their pesticide and plant-growth-promoting effects. In this sense, this study has aimed in evaluating potential SLs-producing Brazilian native strains of Starmerella bombicola isolated from different biomes, considering their potential of assimilating household residual cooking oil (HCO), which represents a renewable feedstock to aid the issues regarding raw material expenditures. The highest SL production (6.2 g/L) was obtained with S. bombicola Y-6419 which was isolated from the Brazilian Cerrado biome. To analyze the viability of using rice bran aqueous hydrolysate (RBH) as an alternative nutrients source, it was implemented a 2(2) factorial design, thereby, the concentration of HCO (g/L) and the supplementation of RBH (% v/v) were evaluated as manipulated variables; as a response, SL production (g/L) was quantified. The RBH showed promising utilization as an elicitor of SLs production by S. bombicola and the final SL titer comprised 51 g/L, which represents an augmentation of approximately ninefold compared to the medium without RBH. SLs were characterized for their physical-chemical properties and their chemical structures were confirmed by HPLC-MS, TLC, and FTIR. Thus, the utilization of agroindustry byproducts and a renewable lipophilic carbon source exhibited marked potential in the production of biosurfactants by the native S. bombicola strain which enables a step towards the consolidation of the bioprocess in modern biorefineries.