Transcriptome profiling of Issatchenkia orientalis under ethanol stress

Yingjie Miao,Peifang Weng,Guotong Xiong,Xin Zhang,Zufang Wu,Ruoyun Li

doi:10.1186/s13568-018-0568-5

Abstract

Issatchenkia orientalis, a non-Saccharomyces yeast that can resist a wide variety of environmental stresses, has potential use in winemaking and bioethanol production. Little is known about gene expression or the physiology of I. orientalis under ethanol stress. In this study, high-throughput RNA sequencing was used to investigate the transcriptome profile of I. orientalis in response to ethanol. 502 gene transcripts were differentially expressed, of which 451 were more abundant, and 51 less abundant, in cells subjected to 4 h of ethanol stress (10% v/v). Annotation and statistical analyses suggest that multiple genes involved in ergosterol biosynthesis, trehalose metabolism, and stress response are differentially expressed under these conditions. The up-regulation of molecular chaperones HSP90 and HSP70, and also genes associated with the ubiquitin–proteasome proteolytic pathway suggests that ethanol stress may cause aggregation of misfolded proteins. Finally, ethanol stress in I. orientalis appears to have a nitrogen starvation effect, and many genes involved in nutrient uptake were up-regulated.

Highlights

Fruit wines are fermented alcoholic beverages that derive their flavors from raw materials as well as from the fermentation process
Ergosterol is an important component of the yeast cytoplasmic membrane and is thought to be involved in stress response
Issatchenkia orientalis, a non-Saccharomyces yeast that can tolerate a variety of stressful environments, is potentially useful in winemaking and bioethanol production

Summary

Introduction

Fruit wines are fermented alcoholic beverages that derive their flavors from raw materials (fruits, and often flowers and herbs) as well as from the fermentation process. The wine yeast Saccharomyces cerevisiae is primarily responsible for alcoholic fermentation and the synthesis of secondary metabolites, while non-Saccharomyces yeasts or non-conventional wine yeasts contribute additional flavor, texture, and nutritional qualities (Archana et al 2015). The role of non-Saccharomyces wine yeasts in fruit wine fermentation has attracted increasing interest (Ciani et al 2010). Several studies have focused on multi-strain fermentation and mixed yeast culture (Fleet 2003; Giovani et al 2012; Sadoudi et al 2012), and some non-Saccharomyces yeasts have been suggested for use in mixed starter cultures with S. cerevisiae (Masneufpomarede et al 2015). The non-conventional wine yeast Issatchenkia orientalis was first described in 1960 but was reclassified to P. kudriavzevii in 1965 (Kurtzman et al 2008). Because of its resistance to multiple stress factors, I. orientalis has potential application in bioethanol production and succinic acid production (Kitagawa et al 2010; Kwon et al 2011; Xiao et al 2014)

Methods

Results

Conclusion