Genetics and metabolic engineering of yeast strains for efficient ethanol production

Abstract

Bioethanol production from monomeric sugar is performed by several yeasts. But there are several limitations associated with yeast strains such as their low tolerance to ethanol, toxic inhibitors, and high sugar concentration. Genetic and metabolic engineering of potential yeast strains can overcome the above limitations. The present article summarized current genetic and metabolic engineering approaches for the development of yeast strain for efficient ethanol production. The review systematically examined bioethanol generations based on substrate utilization, criteria for strain selections, strategies for strain improvements including randomized mutagenesis, genetic engineering, metabolic engineering, genome editing, whole genome (re)sequencing, promoter engineering, quantitative trait locus analysis, protein engineering, and evolutionary engineering. Different fermentation technologies employed in hydrolysate fermentation including low gravity (LG), high gravity (HG), and very high gravity (VHG) as well as challenges of yeast strains development and its future prospect have been critically evaluated in this article. Significant engineering efforts are imminent for yeast‐based second‐generation biofuel to leave a demonstration phase through strain improvement and become economically competitive with fossil fuel. Practical Applications This is a comprehensive review of yeast strain development for bioethanol production. The readers should be able to acquire some basic knowledge on: The accompanied substrates for bioethanol generations as well as the technologies and challenges behind them. The criteria to consider in selecting yeast strain for bioengineering development. Different strategies and their reported applications employed in yeast strain development including randomized mutagenesis, genetic engineering, metabolic engineering, genome editing, whole genome (re)sequencing, promoter engineering, quantitative trait locus (QTL) analysis, protein engineering, and evolutionary engineering. Challenges and merits of different fermentation technologies employed in hydrolysate fermentation including LG, HG, and VHG. Possible challenges to encounter in developing yeast strain for bioethanol production. Desirable traits to consider in the selection and development of yeast strains for bioethanol production.

Metabolic engineering of Saccharomyces cerevisiae for ethanol and butanol biofuel production

“…Due to S. cerevisiae's inability to use hemicellulose sugars naturally due to the absence of pentose fermentation enzymes, xylose catabolizing genes from other microorganisms have been expressed heterologous [24]. In Sakamoto et al study, endogenous xylulokinase (XKS), xylose reductase (XR), and xylitol dehydrogenase (XDH) from Scheffersomyces stipitis were expressed in the recombinant strain of S. cerevisiae to carry out simultaneous saccharification and fermentation (SSF) of rice straw hydrolysate made up of several hemicelluloses.…”

Engineered yeasts and lignocellulosic biomaterials: shaping a new dimension for biorefinery and global bioeconomy

“…They include: randomized mutagenesis, genome editing, QTL analysis, whole genome (re)sequencing, evolutionary engineering, promoter, and protein engineering. However, genetic and metabolic engineering have been mostly used [ 158 ]. The goal of metabolic engineering is to systematically investigate – via molecular biology experiments and computational analysis – metabolic and other pathways in order to enhance cellular properties for the synthesis of desired products, which demands to carry out proper genetic alterations (see supplementary Table S3).…”

OMICs-Based Strategies to Explore Stress Tolerance Mechanisms of Saccharomyces cerevisiae for Efficient Fuel Ethanol Production

“…The regularly intrinsic metabolism pathways can be optimized or directedly altered via inverse metabolic engineering (IME) for efficiently producing desired phenotypes, which a systematic process including 1) choosing the target genes, 2) construction of engineered strain, and 3) high-throughput screening and finetuning on strain breeding (Mehmood et al, 2017b;Pereira et al, 2021). Combined with multi-OMICs data analyses, genetic manipulation has been successfully applied in overexpressing decisive genes affecting metabolic flow, gene deletion, or mutation for blocking and alleviating the competing pathway, even heterologous expression (Liu et al, 2013;Chen and Dou, 2016;Roy et al, 2020); additionally, some approaches such as global transcription machinery engineering (gTME) and multiplex automated genome engineering (MAGE) could be selectively utilized to support the IME for increased alcohol fermentation and stress tolerance (Liu and Jiang, 2015;Adebami et al, 2021). Promoted alcohol tolerance is elicited by overexpressing indigenous genes INO1 (encoding an inositol-3-phosphate synthase), HAL1 (encoding a cytoplasmic protein), and DOG1 (encoding 2-deoxyglucose-6-phosphate phosphatase involved in glucose metabolism) of S. cerevisiae or a truncated form of MSN2 in CEN.…”