Tel: +86-21-64253021; Tel: +86-21-64253853
E-mail address:
juchu@ecust.edu.cn (Ju Chu), tahfy@163.com (Xiwei Tian)
Keywords: Sophorolipids; multiphase system; ultrasonic enhanced
sedimentation; real-time; in-situ separation
Abbreviations: Sophorolipids: SLs; ultrasonic enhanced
sedimentation technology: UEST; The ratio of rapeseed oil to SLs: O/S;
Abstract
Sophorolipids (SLs) are regarded as
one of the most promising biosurfactants. However, high production costs
are the main obstacle to extended SLs application. Semi-continuous
fermentation, which is based on in-situ separation, is a
promising technology for achieving high SLs productivity. In this study,
the
sedimentation
mechanism of SLs was analyzed.
The
formation of a hydrophobic mixture of SLs and
rapeseed
oil was a key factor in sedimentation. And the hydrophobicity and
density of the mixture determined
SLs
sedimentation rate. On this basis,
ultrasonic
enhanced sedimentation technology (UEST) was introduced, by which the
sedimentation rates were increased by 46.9% to 485.4% with different
ratio of rapeseed oil to
SLs.
UEST-assisted real-timein-situ separation and semi-continuous fermentation were
performed. SLs productivity and yield were 2.15 g/L/h and 0.58 g/g,
respectively, simultaneously the loss ratio of cells, glucose, and
rapeseed oil were significantly reduced. This study provides the new
horizon for optimization of the SLs fermentation process.