Effect of manganese ions on ethanol fermentation by xylose isomerase expressing Saccharomyces cerevisiae under acetic acid stress

ABSTRACTDevelopment of acetic acid-resistantSaccharomyces cerevisiaeis important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target,WHI2(encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance inS. cerevisiae. Overexpression ofWHI2significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. TheWHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression ofWHI2gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 inS. cerevisiae. Meanwhile, thewhi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response inS. cerevisiae. Additionally, overexpression ofWHI2and of a cognate phosphatase gene,PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production.

Download Full-text

Effect of by-Products from Wet-Oxidation Explosion on the Growth and Fermentation of Saccharomyces cerevisiae

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.724-725.1116 ◽

2013 ◽

Vol 724-725 ◽

pp. 1116-1121

Author(s):

Mei Zhen Gong ◽

Ru Ming Zhao ◽

Zhi Jun Li ◽

Juan Yao ◽

Da Chun Gong

Keyword(s):

Saccharomyces Cerevisiae ◽

Acetic Acid ◽

Energy Metabolism ◽

Formic Acid ◽

Ethanol Fermentation ◽

Wet Oxidation ◽

The Impact ◽

By Products ◽

Minimum Impact

Effect of by-products from wet-oxidation explosion, such as formic acid, acetic acid, and furfural on the growth and fermentation, glycolysis and energy metabolism, cytomembrane integrality ofSaccharomyces cerevisiaewere studied. The results showed that the maximum tolerated concentra tion ofS. cerevisiaewas 1.8 g/L formic acid , 6.0 g/L acetic acid,2.5g/ furfural, respectively. The inhibition strengths of the typical inhibitors to ethanol fermentation were in the order of formic acid , acetic acid , furfural. When the concentration of these typical inhibitors is 1×IC80, acetic acid has the minimum impact on glycolysis and energy metabolism . When the concentration of these typical inhibitors was 2×IC80, furfural had minimum impact on glycolysis and energy metabolism. However , formic acid can inhibit strongly the glycolysis and energy metabolism ofSaccharomyces cerevisiaewith any concentration . When compared with ethanol, the impact of these typical inhibitors onS. cerevisiae's cytomembrane integrality was not very significant. When the concentration of these typical inhibitors varied from 1×IC80to 3×IC80, the results of the leak of Mg2+was 11%-20% formic acid, 5%-12% acetic acid, 4.5%-8.4% furfural, respectively. However, the result of ethanol that leaded to the leak of Mg2+was 55%.

Download Full-text

Effect of Dissolved Oxygen and Acid on the Yield of 2,3-butanediol by Saccharomyces Cerevisiae W141

10.21203/rs.3.rs-118278/v1 ◽

2020 ◽

Author(s):

ZiLiang Yin ◽

DeAn Liu ◽

ZeMing Ye ◽

Jingping Ge

Keyword(s):

Saccharomyces Cerevisiae ◽

Fatty Acids ◽

Acetic Acid ◽

Dissolved Oxygen ◽

Oxygen Content ◽

Acid Stress ◽

Redox Balance ◽

Short Chain Fatty Acids ◽

Short Chain ◽

Chain Fatty Acids

Abstract Background: The yeast Saccharomyces cerevisiae is a promising host cell to produce 2,3-butanediol (2,3-BDO). However, the fermentation environment restricts 2,3‑BDO yield, productivity, and titre from engineered yeast. In the present study, we propose a strategy in which a suitable dissolved oxygen content and acid stress level can improve the 23-BDO yield of S. cerevisiae W141. Five different concentrations of short-chain fatty acids were evaluated and noxE overexpression was performed to disrupt the intracellular redox balance and alter the NADH content associated with 2,3‑BDO synthesis, which can significantly increase or inhibit 2,3‑BDO yield.Results: The five assayed short-chain fatty acids have different effects on the fermentation characteristics of yeast, were formic, butyric and valeric acids can inhibit the synthesis of 2,3‑BDO. Only low concentrations of acetic and propionic acids could significantly increase the yield of 2,3‑BDO, especially when 1 g/L acetic acid was added, which stimulated the expression of acid stress-related genes in S. cerevisiae W141 (haa1p and hog1p) and increase the 2,3-BDO yield by 29.74%. To further verify that acid stress primarily disrupts the intracellular redox balance by altering the NADH content, we constructed a S. cerevisiae strain, W141-E, which overexpresses the noxE gene of Lactobacillus. After adding 1 g/L acetic acid, the 2,3‑BDO yield from in S. cerevisiae W141-E increased by 43.64%, confirming the validity of our strategy. When the optimized fermentation oxygen content was 0.6 vvm, the 2,3‑BDO yield from S. cerevisiae was greatly improved after the addition of acetic acide.Conclusions: In the present study, we demonstrated that a suitable dissolved oxygen and acid stress are highly effective for increasing the 2,3-BDO yield from S. cerevisiae W141. 2,3-BDO biosynthesis was heavily dependent on the intracellular NADH content, which is closely associated with glycolysis and the TCA cycle and is likely important for the production of 2,3-BDO by S. cerevisiae.

Download Full-text

Study the Effect of pH on the Fermentation Anaerobic-Aerobic Siwalan (Borassus flabellifer L.) Sap to Produce Acetic Acid

EKSAKTA Berkala Ilmiah Bidang MIPA ◽

10.24036/eksakta/vol21-iss1/220 ◽

2020 ◽

Vol 21 (1) ◽

pp. 29-35

Author(s):

Elly Agustiani ◽

Destri Susilaningrum ◽

Atiqa Rahmawati ◽

Fibrillian Z.L. ◽

Dimas L.R.

Keyword(s):

Saccharomyces Cerevisiae ◽

Acetic Acid ◽

Ethanol Fermentation ◽

Anaerobic Fermentation ◽

Acetobacter Aceti ◽

Aerobic Fermentation ◽

Acetic Acid Production ◽

Acid Product ◽

Fermentation Time ◽

Reducing Sugar Concentration

This research is to study the effect of ethanol fermentation aerobic pH on acetic acid product. Anaerobic fermentation uses saccharomyces cerevisiae to produce ethanol, and aerobic fermentation uses acetobacter acetic for acetic acid production. In aerobic ethanol fermentation using pH 3; 3.5; 4 and 5. The ethanol concentration was evaluated using GC ULTRA Scientific Gas Chromatography, DSQ II detector, and MS 220 column. Acetic acid produced was analyzed using an alkalymetric method. Anaerobic fermentation uses Saccharomyces cerevisiae with 1-day log phase, while aerobic fermentation uses acetobacter aceti with a 5-day log phase. Fermentation using saccharomyces cerevisiae within 24 hours so that reduction sugar could stably decrease, optimum ethanol could be got at optimum pH 6 which could decrease 55 % of reducing sugar concentration to produce 8,20583 %v/v ethanol. Fermentation acetate acid content observed in 3 days at pH 6 and 30 ⁰C will produce 6,659 g/l also shows that pH 4-6 at 30 ⁰C will produce 6,605 g/l acetate acid. Aerobic fermentation of acetate acid in 3 days shows that pH 4-6 is highly affected by temperature at 30⁰C. Statistical analysis shows, in ethanol production pH and fermentation time give significant effect, but interaction has no significant effect.

Download Full-text

Biochar-mediated enhanced ethanol fermentation (BMEEF) in Zymomonas mobilis under furfural and acetic acid stress

Biotechnology for Biofuels ◽

10.1186/s13068-020-1666-6 ◽

2020 ◽

Vol 13 (1) ◽

Cited By ~ 2

Author(s):

Wei-ting Wang ◽

Li-chun Dai ◽

Bo Wu ◽

Bu-fan Qi ◽

Tian-fang Huang ◽

...

Keyword(s):

Acetic Acid ◽

Ethanol Fermentation ◽

Zymomonas Mobilis ◽

Acid Stress

Download Full-text

Enhanced acetic acid stress tolerance and ethanol production in Saccharomyces cerevisiae by modulating expression of the de novo purine biosynthesis genes

Biotechnology for Biofuels ◽

10.1186/s13068-019-1456-1 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 19

Author(s):

Ming-Ming Zhang ◽

Liang Xiong ◽

Ya-Jie Tang ◽

Muhammad Aamer Mehmood ◽

Zongbao Kent Zhao ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Acetic Acid ◽

Ethanol Production ◽

Stress Tolerance ◽

De Novo ◽

Acid Stress ◽

Purine Biosynthesis ◽

De Novo Purine Biosynthesis

Download Full-text

A CRISPRi screen of essential genes reveals that proteasome regulation dictates acetic acid tolerance in Saccharomyces cerevisiae

10.1101/2021.04.06.438748 ◽

2021 ◽

Author(s):

Vaskar Mukherjee ◽

Ulrika Lind ◽

Robert P St. Onge ◽

Anders Blomberg ◽

Yvonne Nygård

Keyword(s):

Saccharomyces Cerevisiae ◽

Acetic Acid ◽

High Resolution ◽

Acid Stress ◽

Transport Processes ◽

Essential Genes ◽

26S Proteasome ◽

Organelle Transport ◽

Biomass Hydrolysis ◽

Cell Factories

CRISPR interference (CRISPRi) is a powerful tool to study cellular physiology under different growth conditions and this technology provides a means for screening changed expression of essential genes. In this study, a Saccharomyces cerevisiae CRISPRi library was screened for growth in medium supplemented with acetic acid. Acetic acid is a growth inhibitor challenging the use of yeast for industrial conversion of lignocellulosic biomasses. Tolerance towards acetic acid that is released during biomass hydrolysis is crucial for cell factories to be used in biorefineries. The CRISPRi library screened consists of >9,000 strains, where >98% of all essential and respiratory growth-essential genes were targeted with multiple gRNAs. The screen was performed using the high-throughput, high-resolution Scan-o-matic platform, where each strain is analyzed separately. Our study identified that CRISPRi targeting of genes involved in vesicle formation or organelle transport processes led to severe growth inhibition during acetic acid stress, emphasizing the importance of these intracellular membrane structures in maintaining cell vitality. In contrast, strains in which genes encoding subunits of the 19S regulatory particle of the 26S proteasome were downregulated had increased tolerance to acetic acid, which we hypothesize is due to ATP-salvage through an increased abundance of the 20S core particle that performs ATP-independent protein degradation. This is the first study where a high-resolution CRISPRi library screening paves the way to understand and bioengineer the robustness of yeast against acetic acid stress.

Download Full-text