Starmerella bombicola: recent advances on sophorolipid production and prospects of waste stream utilization

Sophorolipids are among the most extensively studied microbial biosurfactants. Starmerella bombicola is the most productive strain known for sophorolipid production, with volumetric productivity of up to 3.7 g L⁻¹ h⁻¹. This review focuses on the two most important aspects that have an influence on sophorolipid commercialization. Firstly, the metabolic engineering achievements of S. bombicola in the last decade are summarized. Secondly, three improvements of the bioprocess are described, including alternative feedstock, fermentation strategy and specially designed bioreactor. Discussion is made on the waste sources that have been used as feedstock for sophorolipid production, and the review also emphasizes the potential of food waste as nutrient source. Fermentation strategies that correlate with the specially designed bioreactors for commercialization are also discussed in detail.