Semicontinuous sophorolipid fermentation using a novel bioreactor with dual ventilation pipes and dual sieve‐plates coupled with a novel separation system

Abstract

Summary Sophorolipids ( SL s) are biosurfactants with widespread applications. The yield and purity of SL s are two important factors to be considered during their commercial large‐scale production. Notably, SL accumulation causes an increase in viscosity, decrease in dissolved oxygen and product inhibition in the fermentation medium. This inhibits the further production and purification of SL s. This describes the development of a novel integrated system for SL production using Candida albicans O‐13‐1. Semicontinuous fermentation was performed using a novel bioreactor with dual ventilation pipes and dual sieve‐plates ( DVDSB ). SL s were separated and recovered using a newly designed two‐stage separation system. After SL recovery, the fermentation broth containing residual glucose and oleic acid was recycled back into the bioreactor. This novel approach considerably alleviated the problem of product inhibition and accelerated the rate of substrate utilization. Production of SL s achieved was 477 g l −1 , while their productivity was 1.59 g l −1 h −1 . Purity of SL s improved by 23.3%, from 60% to 74%, using DVDSB with the separation system. The conversion rate of carbon source increased from 0.5 g g −1 (in the batch fermentation) to 0.6 g g −1 . These results indicated that the integrated system could improve the efficiency of production and purity of SL s.