Enhanced sophorolipid production by feeding-rate-controlled fed-batch culture.

To develop the easier control method for fed-batch culture of sophorolipid production, we chose rapeseed oil as the most productive oil and compared their productivities in relation to different concentrations of glucose. The optimal concentration of glucose was 30 g/L for sophorolipid production. A fed-batch method was conducted using Candida bombicola ATCC 22214 with rapeseed oil as a secondary substrate. The feeding rate of rapeseed oil was dependent on pH and was calculated by the consumption rate of NaOH and rapeseed oil. The glucose concentration was constantly maintained between 30 and 40 g/L. As a result, we have produced a crude sophorolipid up to 365 g/L for 8 days through a feeding-rate-controlled fed-batch process.