Rational high-throughput screening system for high sophorolipids production in Candida bombicola by co-utilizing glycerol and glucose capacity

Yumeng Lin,Xiwei Tian,Ju Chu,Qianhui Li,Yang Chen

doi:10.1186/s40643-019-0252-x

Yumeng Lin, Xiwei Tian + Show 3 more

Open Access

https://doi.org/10.1186/s40643-019-0252-x

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Abstract

BackgroundA rational and high-performance high-throughput screening system effectively improves the efficiency of strain screening.ResultsA rapid and efficient method was developed to detect carbon sources. And then by using glucose analog as screening pressure and two indexes for sophorolipids (SLs) production and glycerol consumption, a mutant of Candida bombicola L1.3 was successfully selected among 3000 mutants. It produces high SLs titer and co-utilizes glucose and glycerol simultaneously.ConclusionsCompared to the wild-type strain, L1.3 exhibited 15.06% higher SLs titer and 35.69% higher glycerol consumption capacity in a 5-L bioreactor. We believe that L1.3 can potentially be used for the efficient industrial production of SLs with simple downstream processing for separating SLs and glycerol.

Highlights

Sophorolipids (SLs) are biologically derived surfactants harboring a high biodegradability and low toxicity, being widely applied in food, cosmetic, pharmaceutical, and oil industries (Jezierska et al 2018)
Glucose and oil are used as important hydrophilic and hydrophobic substrates, respectively, that are used in the fermentation of SLs (Shah et al 2017)
Bioprocess. (2019) 6:17 concentration of glycerol is usually determined by the periodate oxidation method, gas chromatography (GC), or high-performance liquid chromatography (HPLC) (Wu et al 2011)

Summary

Results

Development of high‐throughput analytical method for carbon sources detection Evaluation of the Cu(OH) method for carbon sources detection After fermentation in a 24-well microplate, 1 M NaOH was added to the broth to obtain an alkaline pH so that the lactone-form of SLs would be hydrolyzed into the acidic-form displaying a relatively high-water solubility. Validation of the fermentation performances of L1.1, L1.3, and L1.5 little changes were observed between the mutants and wild strain regarding cell growth, SLs production and glycerol consumption were significantly increased (Fig. 5). Glucose consumption by L1.1, L1.3, and L1.5 was not significantly different from the wild-type strain, leading to the increase of the ratio between SLs production and total substrate consumption (YSLs/S) These ratios were increased by 3.53, 15.79, and 7.10% for L1.1, L1.3, and L1.5, respectively (Table 1). The oil consumptions of L1.3 and the wild-type strain were 2.88 g/L and 2.51 g/L, respectively, Fig. 3 Effects of different concentrations of 2-deoxy-d-glucose on cell growth. The oil consumptions of L1.3 and the wild-type strain were 2.88 g/L and 2.51 g/L, respectively, Fig. 3 Effects of different concentrations of 2-deoxy-d-glucose on cell growth. a Shake flask; b solid plate indicating that L1.3 consumed more oil than the control, other than the additional glycerol

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Introduction

Materials and methods

Discussion

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