Exogenous Acetic Acid Research Articles

Sexually dimorphic acetyl-CoA biosynthesis and utilization in response to drought and exogenous acetic acid.

Female willows exhibit greater drought tolerance and benefit more from exogenous acetic acid (AA)-improved drought tolerance than males. However, the potential mechanisms driving these sex-specific responses remain unclear. To comprehensively investigate the sexually dimorphic responsive mechanisms of willows to drought and exogenous AA, here, we performed physiological, proteomic, Lys-acetylproteomic, and transgenic analyses in female and male Salix myrtillacea exposed to drought and AA-applicated drought treatments, focusing on protein abundance and lysine acetylation (LysAc) changes. Drought-tolerant females suffered less drought-induced photosynthetic and oxidative damage, did not activate AA and acetyl-CoA biosynthesis, TCA cycle, fatty acid metabolism, and jasmonic acid signaling as strongly as drought-sensitive males. Exogenous AA caused overaccumulation of endogenous AA and inhibition of acetyl-CoA biosynthesis and utilization in males. However, exogenous AA greatly enhanced acetyl-CoA biosynthesis and utilization and further enhanced drought performance of females, possibly determining that AA improved drought tolerance more in females than in males. Interestingly, overexpression of acetyl-CoA synthetase (ACS) could reprogram fatty acids, increase LysAc levels, and improve drought tolerance, highlighting the involvement of ACS-derived acetyl-CoA in drought responses. In addition, drought and exogenous AA induced sexually dimorphic LysAc associated with histones, transcription factors, and metabolic enzymes in willows. Especially, exogenous AA may greatly improve the photosynthetic capacity of S. myrtillacea males by decreasing LysAc levels and increasing the abundances of photosynthetic proteins. While hyperacetylation in glycolysis, TCA cycle, and fatty acid biosynthesis potentially possibly serve as negative feedback to acclimate acetyl-CoA biosynthesis and utilization in drought-stressed males and AA-applicated females. Thus, acetyl-CoA biosynthesis and utilization determine the sexually dimorphic responses of S. myrtillacea to drought and exogenous AA.

Acetic acid delays fresh-cut cassava browning through fine-tunning redox homeostasis

Cassava is one of the important commercial crops in tropical and subtropical regions. However, cassava browning is an important factor restricting its postharvest storage, shelf life and quality. Therefore, suitable approaches are needed to control fresh-cut cassava browning. Acetic acid alleviates the effects of different abiotic stresses and prolongs the shelf life of food. The study aimed to study the effects of exogenous acetic acid on postharvest browning in fresh-cut cassava. The results showed that acetic acid treatment strongly delayed the discoloration during storage through reducing the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), and inhibiting the generation of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as accelerating loss of total phenolic and flavonoid. Notably, acetic acid treatment markedly promoted the accumulation of acetic acid, delayed loss of total starch and had slight impact on jasmonic acid (JA). In addition, JA treatment also delayed discoloration during cassava storage. These findings suggested that the delay of cassava browning via acetic acid treatment could be attributed to maintenance of redox homeostasis by modulating repair of oxidatively damaged proteins, providing a new way to prevent the browning of fresh-cut cassava and elucidates the anti-browning mechanism of acetic acid treatment.

Acetic acid enhances drought tolerance more in female than in male willows.

Drought is an important stress factor that limits plant growth and development. Female willows generally display stronger drought tolerance than males. The application of exogenous acetic acid (AA) has emerged as an efficient and eco-friendly approach to facilitate drought tolerance in willows. However, whether AA exerts sexually different effects on willows remains undefined. In this study, we comprehensively performed morphological and physiological analyses on three willow species, Salix rehderiana, Salix babylonica, and Salix matsudana, to investigate the sexually different responses to drought and AA. The results indicated that willow females were more drought-tolerant than males. AA application effectively enhanced willows' drought tolerance, and females applied with AA displayed greater root distribution and activity, stronger osmotic and antioxidant capacity and photosynthetic rate but less reactive oxygen species, or abscisic acid-mediated stomatal closure than males. In addition, AA application enhanced the jasmonic acid signaling pathway in females but inhibited it in males, conferring stronger drought defense capacity in female willows than in males. Overall, AA application improves drought tolerance more in female than in male willows, further enlarging the sexual differences in willows under drought-stressed conditions.

Optimizing Acetic Acid Application Strategy Can Effectively Promote the Remediation Performance of Oilseed Sunflower on Cd-Contaminated Soils

Applying exogenous organic acids is an effective method to improve the remediation efficiency of Cd-contaminated soils. To investigate the effects of exogenous acetic acid on Cd forms in rhizosphere soils and phytoremediation performance for Cd-contaminated soils, a potted experiment was performed with oilseed sunflower as the extractive plant. Acetic acid was applied at 1, 2, 3, 4, 5, and 6 mmol/kg at 20, 30, 40, and 50 days after seedling emergence. Soil without acetic acid was used as a control (CK). Emblematic chemical properties and different Cd forms in rhizosphere soils were inspected. Results showed that adding acetic acids improved the biomass of shoot and root; it increased firstly and then decreased with the increase of acetic acid concentrations. For all treatments, acetic acids increased sucrase activity and catalase activity but decreased amylase activity in rhizosphere soils. At 30 or 40 days after seedling emergence, the exchangeable Cd content, Fe-Mn oxide Cd content, and organic Cd content were lower, while the carbonate Cd content was greater. Adding acetic acids improved the removal rate of Cd, and when 1 mmol/kg acetic acid was applied at 40 days after seedling emergence, it was increased by 60%, which was the highest compared to CK. RDA showed that catalase activity, sucrase activity, carbonate Cd, and pH could promote the growth of oilseed sunflower, while organic Cd, Fe-Mn oxide Cd, total Cd, exchangeable Cd, and amylase activity inhibited the growth of oilseed sunflower. These findings suggest that acetic acid can improve the efficiency of phytoremediation in Cd-contaminated soils. In particular, the treatment with 1 mmol/kg acetic acid at 40 days after seedling emergence had the most obvious effect.

Mitigation effects of exogenous acetic acid on drought stress in Cunninghamia lanceolata

Mitigation effects of exogenous acetic acid on drought stress in Cunninghamia lanceolata

Acetic acid alters rhizosphere microbes and metabolic composition to improve willows drought resistance

The adverse effects of drought on plants are gradually exacerbated with global climatic change. Amelioration of the drought stress that is induced by low doses of acetic acid (AA) has been caused great interest in plants. However, whether AA can change soil microbial composition is still unknown. Here, we investigated how exogenous AA regulates the physiology, rhizosphere soil microorganisms and metabolic composition on Salix myrtillacea under drought stress. The physiological results showed that AA could improve the drought tolerance of S. myrtillacea. Azotobacter and Pseudomonas were enriched in the rhizosphere by AA irrigation. AA significantly increased the relative contents of amino acid metabolites (e.g., glycyl-L-tyrosine, l-glutamine and seryl-tryptophan) and decreased the relative contents of phenylpropane metabolites (e.g., fraxetin and sinapyl aldehyde) in soils. The enrichments of Azotobacter and Pseudomonas were significantly correlated with glycyl-L-tyrosine, l-glutamine, seryl-tryptophan, fraxetin and sinapyl aldehyde, which could increase the stress resistance by promoting nitrogen (N) uptake for willows. Furthermore, inoculation with Azotobacter chroococcum and Pseudomonas fluorescens could significantly improve willows drought tolerance. Therefore, our results reveal that the changes of plant physiology, rhizosphere soil microorganisms and metabolic composition induced by AA can improve willows drought resistance by enhancing N uptake.

Effect of Endogenous and Exogenous Butyric Acid on Butanol Production From CO by Enriched Clostridia.

Butanol is a potential renewable fuel. To increase the selectivity for butanol during CO fermentation, exogenous acetic acid and ethanol, exogenous butyric acid or endogenous butyric acid from glucose fermentation have been investigated using CO as reducing power, with a highly enriched Clostridium sludge. Addition of 3.2 g/L exogenous butyric acid led to the highest 1.9 g/L butanol concentration with a conversion efficiency of 67%. With exogenous acetate and ethanol supply, the butanol concentration reached 1.6 g/L at the end of the incubation. However, the presence of acetic acid and ethanol favoured butanol production to 2.6 g/L from exogenous butyric acid by the enriched sludge. Finally, exogenous 14 g/L butyric acid yielded the highest butanol production of 3.4 g/L, which was also among the highest butanol concentration from CO/syngas fermentation reported so far. CO addition triggered butanol production from endogenous butyric acid (produced from glucose, Glucose + N2) with as high as 58.6% conversion efficiency and 62.1% butanol yield. However, no efficient butanol production was found from glucose and CO co-fermentation (Glucose + CO), although a similar amount of endogenous butyric acid was produced compared to Glucose + N2. The Clostridium genus occupied a relative abundance as high as 82% from the initial inoculum, while the Clostridia and Bacilli classes were both enriched and dominated in Glucose + N2 and Glucose + CO incubations. This study shows that the supply of butyric acid is a possible strategy for enhancing butanol production by CO fed anaerobic sludge, either via exogenous butyric acid, or via endogenous production by sugar fermentation.

Comprehensive evaluation for the one-pot biosynthesis of butyl acetate by using microbial mono- and co-cultures

BackgroundButyl acetate has shown wide applications in food, cosmetics, medicine, and biofuel sectors. These short-chain fatty acid esters can be produced by either chemical or biological synthetic process with corresponding alcohols and acids. Currently, biosynthesis of short chain fatty acid esters, such as butyl butyrate, through microbial fermentation systems has been achieved; however, few studies regarding biosynthesis of butyl acetate were reported.ResultsIn this study, three proof-of-principle strategies for the one-pot butyl acetate production from glucose through microbial fermentation were designed and evaluated. (1) 7.3 g/L of butyl acetate was synthesized by butanol-producing Clostridium acetobutylicum NJ4 with the supplementation of exogenous acetic acid; (2) With the addition of butanol, 5.76 g/L of butyl acetate can be synthesized by acetate-producing Actinobacillus succinogenes130z (ΔpflA); (3) Microbial co-culture of C. acetobutylicum NJ4 and A. succinogenes130z (ΔpflA) can directly produce 2.2 g/L of butyl acetate from glucose by using microbial co-culture system with the elimination of precursors. Through the further immobilization of A. succinogenes130z (ΔpflA), butyl acetate production was improved to 2.86 g/L.ConclusionDifferent microbial mono- and co-culture systems for butyl acetate biosynthesis were successfully constructed. These strategies may be extended to the biosynthesis of a wide range of esters, especially to some longer chain ones.

Exogenous acetic acid pre-treatment increases drought tolerance of two Indonesian foxtail millet (Setaria italica) accessions

Abstract. Nisa C, Jadid N. 2021. Exogenous acetic acid pre-treatment increases drought tolerance of two Indonesian foxtail millet (Setaria italica) accessions. Biodiversitas 22: 2117-2124. Drought is one of the external factors that affect the productivity of food crops. Some biotechnological approaches had been developed to increase plant resistance to drought stress. Moreover, an adjustment in plant cultivation system is also reported as alternative way to enhance plant resistance to water deficit conditions, especially during their initial vegetative phase. This study aimed to determine the effect of exogenous acetic acid pre-treatment on some Indonesian foxtail millet (Setaria italica) accessions under drought stress conditions. Two different foxtail millet accessions were used in this study: Gambir Manis and Polman Kuning. Morphological and physiological parameters were observed during this study, including plant height, number of leaves, root length, relative water content, total chlorophyll and carotenoid content, and panicle weight. Our results showed that all foxtail millet accessions survived drought stress condition after being pre-treated with exogenous acetic acid. Yet, some morphological parameters were significantly affected. Meanwhile, physiological parameters were not significantly affected. Overall, our data suggest that exogenous acetic acid pre-treatment could enhance drought avoidance in S. italica accessions. This might be due to acetic acid-induced jasmonic acid modulation and secondary metabolites production in S. italica during water deficit exposure.

Insights on acetate-ethanol fermentation by hydrogen-producing Ethanoligenens under acetic acid accumulation based on quantitative proteomics

Ethanoligenens, a novel ethanologenic hydrogen-producing genus, is a representative fermenter in its unique acetate-ethanol fermentation and physiology. Acetic acid accumulation is one of major factors that affect H2-ethanol co-production. However, sufficient information is unavailable on the tolerance mechanisms of hydrogen-producing bacterium in acetic acid stress. The fermentation process of Ethanoligenens harbinense YUAN-3 was significantly slowed down in the selection stress of exogenous acetic acid. The maximum gas production rate of strain YUAN-3 decreased from 192.15 mL·(L-culture)−1·h−1 to 75.2 mL·(L-culture)−1·h−1 with increasing exogenous acetic acid from 0 mM to 30 mM, the batch fermentation period was correspondingly expanded from 66 h to 136 h. Through iTRAQ-based quantitative proteomic approach, 78, 121 and 216 proteins were differentially expressed after strain YUAN-3 was cultured in the medium supplemented with exogenous acetic acid of 10 mM, 20 mM and 30 mM. The up-regulated proteins were mainly involved in β-alanine and pyrimidine metabolism, oxidative stress response, while the down-regulated proteins mainly participated in phosphotransferase system (PTS), fructose and mannose metabolism, phosphate uptake, ribosome, and flagellar assembly. These proteins help to maintain balance between fermentation process and alleviation of intracellular acidification in strain YUAN-3. The study indicated that response to acetic acid stress in strain YUAN-3 was a complex process, which involved multiple metabolic pathways. Reductive pyrimidine catabolic pathway played an important role in the acetic acid resistance of E. harbinense.

Butyric acid production with high selectivity coupled with acetic acid consumption in sugar-glycerol mixture fermentation by Clostridium tyrobutyricum ATCC25755

Butyric acid-producing strain Clostridium tyrobutyricum ATCC25755 produces acetic acid as a byproduct, which lowers butyric acid yield and selectivity. Supplementing glycerol would be a rational approach to enhance a NADH-requiring metabolite butyric acid selectivity by increasing NADH availability; however, there has been no report butyric acid production using glycerol as either a sole carbon source or a co-substrate with C. tyrobutyricum. In this study, glycerol was supplemented along with sugar to increase NADH availability facilitating the production of butyric acid. C. tyrobutyricum was found to simultaneously consume glucose and glycerol only when acetic acid was present. Notably, acetic acid was not produced but consumed. The amount of glycerol consumption was linearly dependent on the amount of acetic acid consumption. When mixed sugars (glucose 80 g/L and xylose 30 g/L) and crude glycerol were used, not only exogenous acetic acid consumption but also acetic acid reassimilation were clearly observed, resulting in significantly enhanced butyric acid production (54.79 g/L), yield (0.464 g/g), and selectivity (98.3%) compared to sugar-only fermentation (production, 35.42 g/L; yield, 0.339 g/g; selectivity, 69.1%). Therefore, this study would pave the way for selective and cost-effective butyric acid production using sugars and glycerol from biodiesel facility.

Phosphorylation by the stress-activated MAPK Slt2 down-regulates the yeast TOR complex 2.

Saccharomyces cerevisiae target of rapamycin (TOR) complex 2 (TORC2) is an essential regulator of plasma membrane lipid and protein homeostasis. How TORC2 activity is modulated in response to changes in the status of the cell envelope is unclear. Here we document that TORC2 subunit Avo2 is a direct target of Slt2, the mitogen-activated protein kinase (MAPK) of the cell wall integrity pathway. Activation of Slt2 by overexpression of a constitutively active allele of an upstream Slt2 activator (Pkc1) or by auxin-induced degradation of a negative Slt2 regulator (Sln1) caused hyperphosphorylation of Avo2 at its MAPK phosphoacceptor sites in a Slt2-dependent manner and diminished TORC2-mediated phosphorylation of its major downstream effector, protein kinase Ypk1. Deletion of Avo2 or expression of a phosphomimetic Avo2 allele rendered cells sensitive to two stresses (myriocin treatment and elevated exogenous acetic acid) that the cell requires Ypk1 activation by TORC2 to survive. Thus, Avo2 is necessary for optimal TORC2 activity, and Slt2-mediated phosphorylation of Avo2 down-regulates TORC2 signaling. Compared with wild-type Avo2, phosphomimetic Avo2 shows significant displacement from the plasma membrane, suggesting that Slt2 inhibits TORC2 by promoting Avo2 dissociation. Our findings are the first demonstration that TORC2 function is regulated by MAPK-mediated phosphorylation.

Biosynthesis and accumulation of GABA in rice plants treated with acetic acid.

Rice seedlings (Oryza sativa) that have died from drought cannot be rescued by watering afterward, but pre-treatment with exogenous acetic acid enabled the plants to produce shoots again after being watered (hereinafter referred to as "drought resilience"). To elucidate the metabolism of acetic acid, we treated rice plants with 13C-labeled acetic acid and traced 13C-labeled metabolites using LC-MS and 13C-NMR techniques. The LC-MS and 13C-NMR spectral data of the root extracts indicated that the acetic acid treatment was absorbed into the plants and then was metabolized to gamma-aminobutyric acid (GABA) by glutamic acid decarboxylase (GAD). GABA accumulation in the roots took place in advance of that in the shoots, and the survival rate against drought stress increased in proportion to the amount of GABA accumulated in the shoots. Therefore, GABA accumulation in shoots may be a key step in drought resilience induced by the acetic acid treatment.

Acetate-mediated novel survival strategy against drought in plants.

Water deficit caused by global climate changes seriously endangers the survival of organisms and crop productivity, and increases environmental deterioration1,2. Plants' resistance to drought involves global reprogramming of transcription, cellular metabolism, hormone signalling and chromatin modification3-8. However, how these regulatory responses are coordinated via the various pathways, and the underlying mechanisms, are largely unknown. Herein, we report an essential drought-responsive network in which plants trigger a dynamic metabolic flux conversion from glycolysis into acetate synthesis to stimulate the jasmonate (JA) signalling pathway to confer drought tolerance. In Arabidopsis, the ON/OFF switching of this whole network is directly dependent on histone deacetylase HDA6. In addition, exogenous acetic acid promotes de novo JA synthesis and enrichment of histone H4 acetylation, which influences the priming of the JA signalling pathway for plant drought tolerance. This novel acetate function is evolutionarily conserved as a survival strategy against environmental changes in plants. Furthermore, the external application of acetic acid successfully enhanced the drought tolerance in Arabidopsis, rapeseed, maize, rice and wheat plants. Our findings highlight a radically new survival strategy that exploits an epigenetic switch of metabolic flux conversion and hormone signalling by which plants adapt to drought.

Enhanced isopropanol and n-butanol production by supplying exogenous acetic acid via co-culturing two clostridium strains from cassava bagasse hydrolysate.

The focus of this study was to produce isopropanol and butanol (IB) from dilute sulfuric acid treated cassava bagasse hydrolysate (SACBH), and improve IB production by co-culturing Clostridium beijerinckii (C. beijerinckii) with Clostridium tyrobutyricum (C. tyrobutyricum) in an immobilized-cell fermentation system. Concentrated SACBH could be converted to solvents efficiently by immobilized pure culture of C. beijerinckii. Considerable solvent concentrations of 6.19g/L isopropanol and 12.32g/L butanol were obtained from batch fermentation, and the total solvent yield and volumetric productivity were 0.42g/g and 0.30g/L/h, respectively. Furthermore, the concentrations of isopropanol and butanol increased to 7.63 and 13.26g/L, respectively, under the immobilized co-culture conditions when concentrated SACBH was used as the carbon source. The concentrations of isopropanol and butanol from the immobilized co-culture fermentation were, respectively, 42.62 and 25.45% higher than the production resulting from pure culture fermentation. The total solvent yield and volumetric productivity increased to 0.51g/g and 0.44g/L/h when co-culture conditions were utilized. Our results indicated that SACBH could be used as an economically favorable carbon source or substrate for IB production using immobilized fermentation. Additionally, IB production could be significantly improved by co-culture immobilization, which provides extracellular acetic acid to C. beijerinckii from C. tyrobutyricum. This study provided a technically feasible and cost-efficient way for IB production using cassava bagasse, which may be suitable for industrial solvent production.

Metabolism of poly-beta-hydroxybutyrate and acetoin in Bacillus cereus.

Kominek, Leo A. (University of Illinois, Urbana), and H. Orin Halvorson. Metabolism of poly-beta-hydroxybutyrate and acetoin in Bacillus cereus. J. Bacteriol. 90:1251-1259. 1965.-The synthesis of poly-beta-hydroxybutyrate (PHB) in Bacillus cereus strain T begins after the cessation of logarithmic growth. Its accumulation is preceded by the formation of acetoacetyl coenzyme A reductase, an enzyme used for its biosynthesis. Exogenous acetic acid present in the medium owing to incomplete glucose oxidation serves as the carbon source for polymer formation during the initial stages of its synthesis. Pyruvic acid is converted to acetoin by an enzyme system that is formed during vegetative growth. The formation of this enzyme system is dependent on a low pH in the medium. As the cells enter the sporulating stage, they lose the ability to form acetoin. The acetoin that accumulates is utilized via the 2,3-butanediol cycle which begins to function late in the sporulation stage. This cycle generates acetic acid which is used for PHB synthesis and is also oxidized to carbon dioxide. PHB accumulation reaches a maximum just prior to the formation of spores, and it is degraded during the process of sporulation. The effect of sporulation inhibitors and pH on PHB and acetoin metabolism are discussed.