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Showing papers on "Acetic acid published in 1999"


Journal ArticleDOI
TL;DR: In this paper, the influence of dilute sulfuric acid hydrolysis of spruce (softwood) on sugar yield and on the fermentability of the hydrolysate by Saccharomyces cerevisiae (Baker's yeast) was investigated.

1,052 citations


Journal ArticleDOI
01 Dec 1999-Polymer
TL;DR: In this paper, the role of protonation on solubilization of chitosan in acetic acid aqueous solution with variable concentration was investigated. But the results were limited to the pK 0.5.

538 citations


Journal ArticleDOI
TL;DR: The results indicated that acetic acid inhibited the fermentation by C. shehatae NJ 23 markedly more than by bakers' yeast, whereas no significant difference in tolerance towards the compounds was detected between the S. cerevisiae strains.
Abstract: The influence of the factors acetic acid, furfural, and p-hydroxybenzoic acid on the ethanol yield (YEtOH) of Saccharomyces cerevisiae, bakers' yeast, S. cerevisiae ATCC 96581, and Candida shehatae NJ 23 was investigated using a 2(3)-full factorial design with 3 centrepoints. The results indicated that acetic acid inhibited the fermentation by C. shehatae NJ 23 markedly more than by bakers' yeast, whereas no significant difference in tolerance towards the compounds was detected between the S. cerevisiae strains. Furfural (2 g L-1) and the lignin derived compound p-hydroxybenzoic acid (2 g L-1) did not affect any of the yeasts at the cell mass concentration used. The results indicated that the linear model was not adequate to describe the experimental data (the p-values of curvatures were 0.048 for NJ 23 and 0.091 for bakers' yeast). Based on the results from the 2(3)-full factorial experiment, an extended experiment was designed based on a central composite design to investigate the influence of the factors on the specific growth rate (mu), biomass yield (Yx), volumetric ethanol productivity (QEtOH), and YEtOH. Bakers' yeast was chosen in the extended experiment due to its better tolerance towards acetic acid, which makes it a more interesting organism for use in industrial fermentations of lignocellulosic hydrolysates. The inoculum size was reduced in the extended experiment to reduce any increase in inhibitor tolerance that might be due to a large cell inoculum. By dividing the experiment in blocks containing fermentations performed with the same inoculum preparation on the same day, much of the anticipated systematic variation between the experiments was separated from the experimental error. The results of the fitted model can be summarised as follows: mu was decreased by furfural (0-3 g L-1). Furfural and acetic acid (0-10 g L-1) also interacted negatively on mu. Furfural concentrations up to 2 g L-1 stimulated Yx in the absence of acetic acid whereas higher concentrations decreased Yx. The two compounds interacted negatively on Yx and YEtOH. Acetic acid concentrations up to 9 g L-1 stimulated QEtOH, whereas furfural (0-3 g L-1) decreased QEtOH. Acetic acid in concentrations up to 10 g L-1 stimulated YEtOH in the absence of furfural, and furfural (0-2 g L-1) slightly increased YEtOH in the absence of acetic acid whereas higher concentrations caused inhibition. Acetic acid and furfural interacted negatively on YEtOH.

417 citations


Journal ArticleDOI
TL;DR: A dynamic model of glucose overflow metabolism in batch and fed‐batch cultivations of Escherichia coli W3110 under fully aerobic conditions is presented and acetate inhibited the specific growth rate according to a noncompetitive model.
Abstract: A dynamic model of glucose overflow metabolism in batch and fed-batch cultivations of Escherichia coli W3110 under fully aerobic conditions is presented. Simulation based on the model describes cell growth, respiration, and acetate formation as well as acetate reconsumption during batch cultures, the transition of batch to fed-batch culture, and fed-batch cultures. E. coli excreted acetate only when specific glucose uptake exceeded a critical rate corresponding to a maximum respiration rate. In batch cultures where the glucose uptake was unlimited, the overflow acetate made up to 9. 0 +/- 1.0% carbon/carbon of the glucose consumed. The applicability of the model to dynamic situations was tested by challenging the model with glucose and acetate pulses added during the fed-batch part of the cultures. In the presence of a glucose feed, E. coli utilized acetate 3 times faster than in the absence of glucose. The cells showed no significant difference in maximum specific uptake rate of endogenous acetate produced by glucose overflow and exogenous acetate added to the culture, the value being 0.12-0.18 g g-1 h-1 during the entire fed-batch culture period. Acetate inhibited the specific growth rate according to a noncompetitive model, with the inhibition constant (ki) being 9 g of acetate/L. This was due to the reduced rate of glucose uptake rather than the reduced yield of biomass.

213 citations


Journal ArticleDOI
TL;DR: The results suggest that E. coli excretes acetate due to the pyruvate flux from PTS and that any method which alleviates the oversupply of acetyl CoA would restore normal growth to the pta mutant.
Abstract: In order to study the physiological role of acetate metabolism in Escherichia coli, the growth characteristics of an E. coli W3100 pta mutant defective in phosphotransacetylase, the first enzyme of the acetate pathway, were investigated. The pta mutant grown on glucose minimal medium excreted unusual by-products such as pyruvate, D-lactate, and L-glutamate instead of acetate. In an analysis of the sequential consumption of amino acids by the pta mutant growing in tryptone broth (TB), a brief lag between the consumption of amino acids normally consumed was observed, but no such lag occurred for the wild-type strain. The pta mutant was found to grow slowly on glucose, TB, or pyruvate, but it grew normally on glycerol or succinate. The defective growth and starvation survival of the pta mutant were restored by the introduction of poly-beta-hydroxybutyrate (PHB) synthesis genes (phbCAB) from Alcaligenes eutrophus, indicating that the growth defect of the pta mutant was due to a perturbation of acetyl coenzyme A (CoA) flux. By the stoichiometric analysis of the metabolic fluxes of the central metabolism, it was found that the amount of pyruvate generated from glucose transport by the phosphoenolpyruvate-dependent phosphotransferase system (PTS) exceeded the required amount of precursor metabolites downstream of pyruvate for biomass synthesis. These results suggest that E. coli excretes acetate due to the pyruvate flux from PTS and that any method which alleviates the oversupply of acetyl CoA would restore normal growth to the pta mutant.

207 citations


Journal ArticleDOI
TL;DR: Wine chemical analyses showed statistically significant differences depending on the yeast strain used, and some strains had peculiar characteristics, such as an uncommonly high concentration of n-propanol and 3-ethoxy Propanol.
Abstract: Nine Saccharomyces cerevisiae and four Saccharomyces bayanus strains used in the production of Trebbiano wine were examined. The aim of this study is to evaluate the different abilities of various yeast strains in wine-making. The possibility of yeast discrimination on the basis of their volatile production is another possibility. Wine chemical analyses showed statistically significant differences depending on the yeast strain used. Some compounds such as 2-phenylethanol, 2-phenethyl acetate, ethyl lactate, 3-ethoxypropanol, and, to a lesser extent, diethyl succinate and propionic acid characterized examined Saccharomyces bayanus yeasts. Moreover, these strains did not produce any undesirable compounds, such as acetic acid and sulfur anhydride. For these reasons and because they synthesized malic acid, they could be more suitable for white wine production. The other yeasts showed great differences, which are difficult to correlate with the strain. However, some strains had peculiar characteristics, such as an uncommonly high concentration of n-propanol and 3-ethoxypropanol.

193 citations


Journal ArticleDOI
TL;DR: In this paper, the changes in pH and density during dissolution, rate of dissolution, and productivity per liter of acid provide a means for selecting the economically optimal process, monitoring the progress, and adjusting the composition of the solution when necessary.
Abstract: When extracting or cleaning phosphatic fossils using acetic acid, the solutions must be buffered with calcium acetate to a pH greater than 3.6 for conodont and many fish taxa, and to a slightly greater pH for some conulariid, shark, and some fish taxa. Diagrams of the changes in pH and density during dissolution, rate of dissolution, and productivity per liter of acid provide a means for selecting the economically optimal process, monitoring the progress, and adjusting the composition of the solution when necessary.

175 citations


Patent
07 Sep 1999
TL;DR: In this paper, a modified water-immiscible solvent is used for the extraction of acetic acid from aqueous streams, which is a substantially pure mixture of isomers of highly branched di-alkyl amines.
Abstract: A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. This solvent is substantially devoid of mono-alkyl amines and alcohols. Solvent mixtures formed of such a modified solvent with a desired cosolvent, preferably a low boiling hydrocarbon which forms an azeotrope with water are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

165 citations


Journal ArticleDOI
TL;DR: In this article, a catalytic cycle has been proposed for the acylation reaction of alcohols, phenols, amines and thiols with acetic anhydride in CH 2 Cl 2 or acetic acid.

161 citations


Journal ArticleDOI
TL;DR: In this article, the photocatalytic oxidations of methanol, ethanol and chloroform, trichloroethylene (TCE), and dichloropropionic acid (DCP) in M/TiO2 aqueous slurries are studied.

142 citations


Journal ArticleDOI
TL;DR: Inducing pH-dependent acid resistance increased the already substantial acid tolerance of stationary-phase E. coli, and Hydrochloric acid was consistently the least damaging to cells; lactic acid was the most detrimental.

Journal ArticleDOI
TL;DR: The addition of acetate to MP2 medium may induce the expression of the sol operon, which ensures solvent production and prevents strain degeneration in Clostridium beijerinckii NCIMB 8052.
Abstract: The addition of sodium acetate to chemically defined MP2 medium was found to increase and stabilize solvent production and also increase glucose utilization by Clostridium beijerinckii NCIMB 8052. RNA and enzyme analyses indicated that coenzyme A (CoA) transferase was highly expressed and has higher activity in C. beijerinckii NCIMB 8052 grown in MP2 medium containing added sodium acetate than in the microorganism grown without sodium acetate. RNA analysis suggested the existence of a sol operon and confirmed the presence of a ptb-buk operon in C. beijerinckii NCIMB 8052. In addition to CoA transferase, C. beijerinckii NCIMB 8052 grown in MP2 medium containing added acetate demonstrated higher acetate kinase- and butyrate kinase-specific activity than when the culture was grown in MP2 medium containing no added acetate. Southern blot analysis with chromosomal DNA isolated from solventogenic and degenerated C. beijerinckii NCIMB 8052 indicated that C. beijerinckii NCIMB 8052 strain degeneration does not involve loss of the CoA transferase genes. The addition of acetate to MP2 medium may induce the expression of the sol operon, which ensures solvent production and prevents strain degeneration in C. beijerinckii NCIMB 8052.

Journal ArticleDOI
TL;DR: In this paper, atmospheric gas and particle-phase carboxylic acids were measured during July 1996, Winter, in an urban area of Sao Paulo, a highly polluted Latin American city.

Journal ArticleDOI
TL;DR: Competition experiments suggest that P450 2E1 binds acetic acid and acetaldehyde with relatively high K d values, which preclude simple tight binding as an explanation for rate-limiting product release, and k cat is similar for both reactions, suggesting a possible common catalytic mechanism.

Patent
22 Dec 1999
TL;DR: In this article, an improved process for producing ethyl acetate comprising contacting acetic acid and ethanol in a reaction zone in the presence of an acid catalyst, distilling formed vapors and condensing to form an organic phase rich in ethanol and an aqueous phase in water, separating the phases and further distilling each phase to obtain a final purified product and a water stream low in organic components.
Abstract: Disclosed herein is an improved process for producing ethyl acetate comprising contacting acetic acid and ethanol in a reaction zone in the presence of an acid catalyst, distilling formed vapors and condensing to form an organic phase rich in ethyl acetate and an aqueous phase rich in water, separating the phases and further distilling each phase to obtain a final purified ethyl acetate product and a water stream low in organic components, the improvement comprising directing the organic phase from the first distillation to the reaction zone. An alternate embodiment involves directing at least a portion of the organic phase from the first distillation to a membrane separation unit which removes water and/or alcohol from the organic phase rich in ethyl acetate.

Journal ArticleDOI
TL;DR: In vitro studies showed that these polymers underwent rapid hydrolytic degradation in 10 days, and extensive biocompatibility study demonstrated their toxicological inertness and biodegradability.
Abstract: Polyanhydrides synthesized from pure ricinoleic acid half-esters with maleic and succinic anhydrides possess desired physicochemical and mechanical properties for use as drug carriers. Ricinoleic acid maleate or succinate diacid half-esters were prepared from the reaction of crude ricinoleic acid (85% content) with succinic or maleic anhydride. The pure diacid monomers were obtained by chromatography purification through silica gel using petroleum ether/ethyl acetate/acetic acid (80/30/1 v/v/v) mixture as eluent. The pure diacid monomers (>99%) were polymerized by melt condensation to yield film-forming polymers with molecular weights exceeding 40,000 with a polydispersity of 2. Extensive biocompatibility study demonstrated their toxicological inertness and biodegradability. Their rate of elimination from rats in the course of about 4-6 weeks was faster than that found for similar fatty acid-based polyanhydrides previously tested. In vitro studies showed that these polymers underwent rapid hydrolytic degradation in 10 days. Methotrexate release from the polymers was not affected by the initial polymer molecular weight in the range of 10,000-35,000. The in vitro drug release correlated with the degradation of the polymers. The fatty acid ester monomers were further degraded to its counterparts, ricinoleic acid and succinic or maleic acid.

Journal ArticleDOI
TL;DR: Synthesis of 6-O-acylate-α-d-glycopyranose from underivatised substrates in anhydrous tert-butanol was achieved using immobilised lipases from Candida antarctica and Mucor miehei using maltose as substrate while with maltotriose no reaction was observed.
Abstract: Synthesis of 6-O-acylate-α-d-glycopyranose from underivatised substrates in anhydrous tert-butanol was achieved using immobilised lipases from Candida antarctica and Mucor miehei. Except for acetic acid, the initial reaction rates with the C. antarctica lipase were independent of acyl donor chain lengths and in a range of 3.9±0.4 μmol glucose converted min−1 g enzyme preparation. The catalytic activity of the M. miehei lipase increased with increasing acyl donor chain length with a maximum for stearic acid of 0.45 μmol min−1 g. Using maltose as substrate, the catalytic activity decreased by a factor of 48 and 20 with the lipase from C. antarctica and M. miehei, respectively, while with maltotriose no reaction was observed.

Journal ArticleDOI
TL;DR: In this paper, a poly(l-lactide) was ring-opening polymerized in the melt by using different organic monocarboxylic iron complexes, such as iron and acetic acid, butyric acid, isobutyric acid and dichloroacetic acid.
Abstract: l-Lactide was ring-opening polymerized in the melt by using different organic monocarboxylic iron complexes. The complexes were those of iron and acetic acid, butyric acid, isobutyric acid, dichloroacetic acid, and trifluoroacetic acid. The polymerization temperature was in the range 170−210 °C, polymerization time between 0.5 and 25 h, and amount of catalyst added varied between 0.12 and 1.20 wt %. Iron butyrate and iron dichloroacetate complexes were low efficient catalysts in the ring-opening polymerization due to hydrolysis during the preparation. Iron acetate, iron trifluoroacetate, and iron isobutyrate complexes were efficient catalysts yielding a high molar mass poly(l-lactide) with a high monomer conversion. Under optimum conditions a poly(l-lactide) with a molar mass (Mw) of ca. 150 000 g/mol could be prepared. Monomer conversions over 85% were obtained in many experiments. High polymerization temperatures are required though with these kinds of iron catalysts, and some racemization of the polyme...

Journal ArticleDOI
TL;DR: The formation of vitisin A, an anthocyanin formed naturally in small quantities in maturing port wines, was studied in model wine solutions at a range of pH values and pyruvate concentrations and on aging, the model solutions changed from a bluish red to a slightly more orange red, attributable to the vitisin compounds.
Abstract: The formation of vitisin A, an anthocyanin formed naturally in small quantities in maturing port wines, was studied in model wine solutions at a range of pH values (2.0−4.5) and pyruvate concentrations [molar ratios of pyruvic acid to total anthocyanins (PA/TA) ranging from 12.20 to 172.40]. Additionally, the effect of vitisin A formation on the color changes of these model wines was evaluated. Vitisin A was formed through the interaction between malvidin 3-glucoside and pyruvic acid, and vitisin A in acylated forms, having the 6-position of the sugar acylated with acetic acid (3-acetylvitisin A) and p-coumaric acid (3-p-coumarylvitisin A), formed through the interaction between pyruvic acid and malvidin 3-acetylglucoside and malvidin 3-p-coumarylglucoside, respectively; their identities were confirmed by spectral analysis and FABMS. The maximum formation of these new anthocyanin derivatives was at pH 2.7−3.0, at the higher pyruvic acid concentration (PA/TA of 172.40 units). The vitisins A caused changes ...

Journal ArticleDOI
TL;DR: In this article, different cellulosic materials (pure cellulose, cotton, tissues and recycling paper) were degraded under the chemical conditions of cement pore water (pH 13.3) and characterized using different separation techniques (HPIEC, HPAEC, GC-MS, MS/MS) and by high resolution 1H-NMR spectroscopy.

Journal ArticleDOI
TL;DR: In this article, the viability of using photocatalytic oxidation with titanium dioxide to degrade Cd-EDTA was examined at concentrations from 2 × 10-5 to 10-3 M at pH from 3 to 8.
Abstract: Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as cadmium. Metal-EDTA chelates are chemically stable and occur in a number of waste situations. The viability of using photocatalytic oxidation with titanium dioxide to degrade Cd-EDTA was examined at concentrations from 2 × 10-5 to 10-3 M at pH from 3 to 8. Initially a portion of the complex was adsorbed onto the TiO2 photocatalyst at low pH. However, independent of the degree of initial adsorption, Cd-EDTA was rapidly destroyed with little dependence on pH. Concurrently, in most cases cadmium was liberated as Cd2+ with no affiliation with organic reaction products; its fate depended on suspension pH. At low pH, Cdaq2+ was released into solution. Also, organic carbon was released into solution as oxidation of adsorbed EDTA occurred. At higher pH the Cd was adsorbed onto the TiO2 at adsorption equilibrium levels. Major products detected include formaldehyde, formic acid, and acetic acid. Nitrate and glyoxylic, malonic, a...

Journal ArticleDOI
TL;DR: It is suggested that dietary vinegar enhanced intestinal calcium absorption by improving calcium solubility and by the trophic effect of the acetic acid contained in vinegar, which would reduce the bone turnover caused by ovariectomy and be helpful in preventing osteoporosis.
Abstract: We studied the effect of dietary vinegar on calcium absorption by using ovariectomized rats fed on a low-calcium diet. The apparent absorption of calcium was higher when the rats were fed on a diet containing 1.6% vinegar for 32 days than when fed on a diet without vinegar (P<0.05). The calcium content in the femur of the rats given diets containing 0.4% and 1.6% vinegar were also higher (P<0.05). The serum parathyroid hormone level was lower and the crypt depth of the duodenum thicker in the rats fed on a diet containing 1.6% vinegar (P<0.05). These results suggest that dietary vinegar enhanced intestinal calcium absorption by improving calcium solubility and by the trophic effect of the acetic acid contained in vinegar, which would reduce the bone turnover caused by ovariectomy and be helpful in preventing osteoporosis.

Journal ArticleDOI
TL;DR: Fumigation with gaseous acetic acid was also lethal to indigenous bacteria and fungi on mung bean seed, and the treatment did not significantly reduce seed germination rates, and no differences in surface microstructure were observed between treated and untreated seed viewed by scanning electron microscopy.

Journal ArticleDOI
TL;DR: A thin-film tin oxide gas sensor was tested in a flow system for the sensitivity to each vapor (10, 10 2, 10 3 ppm in air) of methanol, ethanol, isopropanol, acetone and acetic acid as discussed by the authors.
Abstract: A thin-film tin oxide gas sensor was tested in a flow system for the sensitivity to each vapor (10, 10 2 , 10 3 ppm in air) of methanol, ethanol, isopropanol, acetone and acetic acid. With a change in operating temperature, the sensitivity to each vapor went through a maximum around 450°C. When compared at the same vapor concentration, the sensitivity was in the order of acetic acid>isopropanol>ethanol>acetone>methanol. This sequence was interpreted as resulting from the differences in ability to reduce tin oxide among the vapors.

Journal ArticleDOI
TL;DR: Cell growth and succinic acid production were slightly enhanced at the optimum magnesium ion concentration, and among the seven different complex nitrogen sources examined by Plackett–Burman design, only poylpeptone enhanced succinic Acid production.

Journal ArticleDOI
TL;DR: A new process for acetic acid production by direct oxidation of ethylene which was established and commercialized is described in this article, where the catalyst system consisting of Pd and heteropoly acid exhibits excellent activity and selectivity.
Abstract: A new process for acetic acid production by direct oxidation of ethylene which was established and commercialized is described. The catalyst system consisting of Pd and heteropoly acid exhibits excellent activity and selectivity. The addition of Se or Te to the catalyst system is effective to suppress the formation of carbon dioxide. This new process is applicable to a plant of a wide range of size corresponding to the local demand. Because this new process produces little waste water, it is very friendly to the environment.

Patent
29 Jun 1999
TL;DR: In this paper, a method for removing organometallic and organosilicate residues remaining after a dry etch process from semiconductor substrates is presented, where the substrate is exposed to a conditioning solution of phosphoric acid, hydrofluoric acid and a carboxylic acid, such as acetic acid.
Abstract: A method for removing organometallic and organosilicate residues remaining after a dry etch process from semiconductor substrates. The substrate is exposed to a conditioning solution of phosphoric acid, hydrofluoric acid, and a carboxylic acid, such as acetic acid, which removes the remaining dry etch residues while minimizing removal of material from desired substrate features. The approximate proportions of the conditioning solution are typically 80 to 95 percent acetic acid, 1 to 15 percent phosphoric acid, and 0.01 to 5.0 percent hydrofluoric acid.

Dissertation
01 Jan 1999
TL;DR: Fed-batch fermentation was suggested as a suitable mode of operation for fermenting dilute-acid hydrolyzates from the physiological studies of the inhibitors and a simple feedback control strategy was developed, allowing the feed rate to be determined on-line, without any other input variable than the measured carbon dioxide evolution rate.
Abstract: Fermentative ethanol production from dilute-acid hydrolyzates of wood using the yeast Saccharomyces cerevisiae was investigated. Of known inhibitors in hydrolyzates, acetic acid, furfural and hydroxymethyl furfural (HMF) were found in the highest concentrations (up to about 10 g/l). Physiological effects of these inhibitors were studied in synthetic media. Based on these studies, on-line control of fed-batch cultivation for in-situ detoxification of the hydrolyzates was subsequently developed. The effect of acetic acid on yeast was found to strongly depend on pH. At concentration of undissociated acetic acid higher than 5 g/l, growth stopped. However, presence of the acid in the medium at low concentration (e.g. 1 g/l) increased ethanol yield and decreased the formation of fermentation by-products. Furfural (4 g/l) severely decreases the specific growth rate of S. cerevisiae in pulse addition experiments. However, the yeast was able to convert furfural to less inhibiting products, mainly by reduction to furfuryl alcohol, with a specific conversion rate of 0.6 g/g.sigma.h. A previously unidentified metabolite was also found and was characterized by mass spectrometry. Presumably, the metabolite was formed from pyruvate and furfural. HMF is less inhibiting to yeast than furfural, but remains in the medium for about 4 times longer than furfural due to a lower conversion rate. The yeast converts HMF mainly to hydroxymethyl-furfuryl alcohol and a newly identified compound probably formed from HMF and acetaldehyde. Fed-batch fermentation was suggested as a suitable mode of operation for fermenting dilute-acid hydrolyzates from the physiological studies of the inhibitors. With a suitable feed rate, it was possible to ferment also severely inhibiting spruce and birch hydrolyzates using fed-batch operation without any pretreatment of the hydrolyzates. However, the feed rate was critical in order to obtain a successful operation. A simple feedback control strategy was therefore developed, allowing the feed rate to be determined on-line, without any other input variable than the measured carbon dioxide evolution rate.

Journal ArticleDOI
TL;DR: It is shown that organic acids differ in their inhibitory or lethal activity against acid- Adapted and unadapted E. coli O157:H7 cells, and acid-adapted cells are more tolerant than un Adapted cells when subsequently exposed to reduced pH caused by these acids.

Patent
12 Feb 1999
TL;DR: In this paper, a process for the preparation of esters from alcohols using acetic acid as acetylating agent and clays as catalysts was described, which consisted of the extraction and recovery of the corresponding esters by simple work-up procedure.
Abstract: The present invention relates to a process for the preparation of esters from alcohols using acetic acid as acetylating agent and clays as catalysts, which comprises the preparation of esters in a single step from the reaction of aliphatic, acyclic, cyclic, heterocyclic, α,β-unsaturated and aromatic alcohols with carbon atoms in the range of C 1 to C 10 with acetic acid in a molar ratio of 1:3 to 11 using reusable natural montmorillonite/metal ion-exchanged clay catalysts in the solvent medium of aliphatic, aromatic, or chlorinated hydrocarbons at 30-140° C. for a period in the range of 0.02 to 3.0 hrs, and recovering the corresponding esters by simple work-up procedure.