Nonionic surfactants and their effects on asymmetric reduction of 2-octanone with Saccharomyces cerevisiae

Yunquan Zheng,Xianai Shi,Liangbin Li,Feng Li,Zhijian Huang,Jianmin Yang,Yanghao Guo

doi:10.1186/s13568-018-0640-1

Abstract

In an aqueous buffer system, serious reverse and side reactions were found in the asymmetric reduction of 2-octanone with Saccharomyces cerevisiae. However, some nonionic surfactants added to the aqueous buffer system improved the bioreduction process by decreasing the reverse and side reaction rates in addition to effectively increasing the average positive reaction rate. Further, a shorter carbon chain length of hydrophilic or hydrophobic moieties in surfactants resulted in a higher yield of (S)-2-octanol. The alkylphenol ethoxylate surfactants had a less influence than polyoxyethylenesorbitan trialiphatic surfactants on the product e.e. It suggested that the product e.e. resulting from the change of carbon chain length of the hydrophobic moieties varied markedly compared with the change of carbon chain length of the hydrophilic moiety. Emulsifier OP-10 and Tween 20 markedly enhanced the yield and product e.e. at the concentration of 0.4 mmol L−1 with a yield of 73.3 and 93.2%, and the product e.e. of 99.2 and 99.3%, respectively, at the reaction time of 96 h.

Highlights

The yeast Saccharomyces cerevisiae contains alcohol dehydrogenases and other redox enzymes (Berlowska et al 2006; Heidlas et al 1991; Leskovac et al 2002; Xu et al 2005; De Smidt et al 2008, 2012) which can catalyze bioreduction of ketones to optically active alcohols (Hummel 1997; Heidlas and Tressl 1990; Jung et al 2010; Gonzalez et al 2000)
Emulsifier octylphenol polyoxyethylene (OP)-6 consists of alkylphenol ethoxylates (APEO) and does not dissociate in water
To investigate the effect of surfactants in asymmetric reduction of 2-octanone with S. cerevisiae, we introduced surfactants into the aqueous media and the yield and product e.e. value of the reaction were analyzed

Summary

Introduction

The yeast Saccharomyces cerevisiae contains alcohol dehydrogenases and other redox enzymes (Berlowska et al 2006; Heidlas et al 1991; Leskovac et al 2002; Xu et al 2005; De Smidt et al 2008, 2012) which can catalyze bioreduction of ketones to optically active alcohols (Hummel 1997; Heidlas and Tressl 1990; Jung et al 2010; Gonzalez et al 2000). Surfactants are associated with these functions, (1) solubilization of hydrophobic substrates and products in the medium (Ganesh et al 2006; Mahdi et al 2011; Wang et al 2004; Walters and Aitken 2001) to avoid their enrichment in the cell membranes, which reduce their concentration in cells; (2) formation of mixed micelles including surfactants and cell membranes (Hu et al 2012; Liu et al 2016; Kurakake et al 2017), which affecting the structure and permeability of cell membrane, leading to altered physiology of cells and transmembrane transportation of substrates and products; (3) interaction of surfactants and intracellular enzymes, which changes the enzymatic characteristics and shifts enzymatic activities

Methods

Results

Conclusion