Zmo0994, a novel LEA-like protein from Zymomonas mobilis , increases multi-abiotic stress tolerance in Escherichia coli
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Biotechnology for Biofuels Open Access
RESEARCH
Zmo0994, a novel LEA‑like protein from Zymomonas mobilis, increases multi‑abiotic stress tolerance in Escherichia coli Jungwoo Yang1, Ha Eun Kim1, Young Hoon Jung2, Jungyeon Kim1, Do Hyoung Kim1, Adrian R. Walmsley3 and Kyoung Heon Kim1*
Abstract Background: Pretreatment processes and subsequent enzymatic hydrolysis are prerequisites to utilize lignocellulosic sugar for fermentation. However, the resulting hydrolysate frequently hinders fermentation processes due to the presence of inhibitors and toxic products (e.g., ethanol). Thus, it is crucial to develop robust microbes conferring multi-stress tolerance. Results: Zmo0994, a functionally uncharacterized protein from Zymomonas mobilis, was identified and characterized for the first time. A major effect of Zmo0994 was a significant enhancement in the tolerance to abiotic stresses such as ethanol, furfural, 5′-hydroxymethylfurfural and high temperature, when expressed in Escherichia coli. Through transcriptome analysis and in vivo experiments, the cellular mechanism of this protein was revealed as due to its ability to trigger genes, involved in aerobic respiration for ATP synthesis. Conclusions: These findings have significant implications that might lead to the development of robust microbes for the highly efficient industrial fermentation processes. Keywords: Abiotic stress, Inhibitors, Multi-stress tolerance, Zmo0994, Zymomonas mobilis Background Recent climate changes due to the long-term use of fossil fuels have necessitated the development of renewable non-fossil fuels, such as bioethanol, to meet increasing global energy needs [1]. Bioethanol is a product of microbial fermentation of sugars from starch and, more recently, lignocellulosic biomass [2]. Lignocellulosic biomass is generally referred to as non-food biomass and is obtained from other organic sources such as wood, grass, and various wastes, which are recalcitrant to natural degradation [2]. Thus, pretreatment and subsequent enzymatic hydrolysis are prerequisites to *Correspondence: [email protected] 1 Department of Biotechnology, Graduate School, Korea University, Seoul 02841, Republic of Korea Full list of author information is available at the end of the article
utilizing the lignocellulosic sugar for fermentation [3]. This pretreatment, using such as dilute acid at an elevated temperature, is effective for the hydrolysis of pentose polymers in hemicellulose, increasing the access of cellulases to cellulose fibers [4]. However, the resulting hydrolysate by this diluted acid pretreatment, which is most widely employed on an industrial scale, frequently hinders fermentation processes due to the presence of inhibitors, such as furfural and 5′-hydroxymethylfurfural (HMF) [5]. In addition to the presence of such inhibitors, hydrolysate fermentation on an industrial scale generally occurs under environmental stresses, such as temperature fluctuation, hyper-osmosis, and accumulation of toxic end products that inhibit fermentation, thereby resulti
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