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

• Published in: Microbial biotechnology 2018-05, Vol.11 (3), p.455-464
• Main Authors: Zhang, Yaguang, Jia, Dan, Sun, Wanqi, Yang, Xue, Zhang, Chuanbo, Zhao, Fanglong, Lu, Wenyu
• Format: Article
• Language: English
• Subjects: Bioreactors; Bioreactors - microbiology; Biosurfactants; Candida albicans - growth & development; Candida albicans - metabolism; Carbon; Carbon sources; Cell growth; Dissolved oxygen; Experiments; Fermentation; Glucose; Oleic acid; Oleic Acids - metabolism; Oxygen - metabolism; Pipes; Plates; Product inhibition; Purification; Purity; Stage separation; Studies; Vegetable oils; Ventilation; Ventilation - methods; Viscosity
• ISSN: 1751-7915; 1751-7915
• DOI: 10.1111/1751-7915.13028

Summary Sophorolipids (SLs) are biosurfactants with widespread applications. The yield and purity of SLs 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 SLs. 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). SLs 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 SLs achieved was 477 g l−1, while their productivity was 1.59 g l−1 h−1. Purity of SLs 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 SLs. A novel fermentatation bioreactor and a two‐stage separation system were conducted for the improvement of SLs production. The integrated fermentation and two‐stage separation technology relieved the product inhibition to perform better in sophorolipids productivity and purity.