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

Abstract

SummarySophorolipids (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.

Sunflower Acid Oil‐Based Production of Rhamnolipid Using Pseudomonas aeruginosa and Its Application in Liquid Detergents

“…However, few studies have reported the effect of the viscous nature of the fermentation broth on microbial growth and productivity. An increase in the concentration of hydrophobic substrates causes an increase in broth viscosity, a decrease in dissolved oxygen, and product inhibition in the fermentation medium (Zhang et al, ). In case of SAO, increasing the concentration from 60 to 80 g L −1 leads to a decrease in biomass due to oxygen limitation hence reducing the productivity.…”

Microbial biosurfactant research: time to improve the rigour in the reporting of synthesis, functional characterization and process development

“…It is hard to meet those prerequisites if using the anthrone method on crude culture broth: other sugars, either derived from the supplemented carbon source or from cell wall components, are also present and not every laboratory uses sophorolipid as a standard for the calibration curve. Hence, practices where sophorolipid concentration is determined by applying the anthrone method to measure total carbohydrate, followed by subtraction of glucose concentration obtained by another method, are questionable (Zhang et al ., 2018). Nevertheless, both orcinol and anthrone reagent can be used as detection reagent for glycolipids upon thin‐layer chromatography (TLC) analysis, as discussed below.…”

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

“…Also, as a platform yeast, several new‐to‐nature glucolipids were created such as bolaform sophorolipids that have attractive properties. The highest titer and volumetric productivity being reported currently are 477 g L −1 and 3.7 g L −1 h −1 respectively with specific bioprocessing optimization . However, it is important to consider the highest productivity reported by Gao et al .…”

“…The highest titer and volumetric productivity being reported currently are 477 g L −1 and 3.7 g L −1 h −1 respectively with specific bioprocessing optimization. 35,51 However, it is important to consider the highest productivity reported by Gao et al 51 As they mentioned, their purpose was to verify the feasibility of enhancing volumetric productivity by means of high-cell-density fermentation. Their experimental design was more likely to detect the productivity limitation of S. bombicola.…”

“…Compared with a fed‐batch system, the sophorolipid productivity was increased by 50%. Furthermore, the separation set‐up could resolve the problem of sophorolipid accumulation which increases the viscosity of the broth and subsequently causes a decrease in dissolved oxygen and product inhibition . Figure shows another more systematic design by Zhang et al .…”