Biodegradation of methyl and ethyl acetates by immobilized Pseudomonas esterophilus cells

A biofilter was created based on polyvinylformal foam and Pseudomonas esterophilus strain VKM V-1436D cells, which utilize methyl and ethyl acetates as sources of carbon and energy. A complete conversion of methyl and ethyl acetate (2000 mg/l) under flow conditions was reached. Because carboxyl esterase does not exhibit specificity for these esters, no adaptation period was required for switching the biofilter between biodegradation of methyl acetate and ethyl acetate.     

Performance and Microbial Diversity of a Trickle‐Bed Air Biofilter under Interchanging Contaminants

A trickle‐bed air biofilter (TBAB) was evaluated under conditions of interchanging the feed volatile organic compounds (VOCs) in the sequence methyl ethyl ketone (MEK), toluene, methyl isobutyl ketone (MIBK), styrene, and then back to MEK. The obtained performance results revealed that the biofilter provided high removal efficiency within the critical loading of each VOC, which was previously defined in the non‐interchanging VOC fed biofilter. The biofilter easily acclimated to the oxygenated compounds (MEK and MIBK), but re‐acclimation was delayed for the aromatic compounds (toluene and styrene). Ratios of the molar mass of CO₂ produced per molar mass of VOC removed were investigated. It has been found that the ratios for the aromatic compounds closely resembled the theoretical complete chemical oxidation based ratios while larger differences were encountered with the oxygenated compounds. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes was used to assess the impact of interchanging VOCs on the bacterial community structure in the biofilter. The results from denaturing gradient gel electrophoresis (DGGE) showed that the structure of the microbial community in the biofilter was different after each interchange of VOCs.     

Biofiltration of ethyl acetate and amyl acetate using a composite bead biofilter

Biodegradation kinetic behaviors of ethyl acetate and amyl acetate in a composite bead biofilter were investigated. The composite bead was the spherical PVA/peat/KNO(3)/GAC composite bead which was prepared in our previous works. Both microbial growth rate and biochemical reaction rate were inhibited at higher inlet concentration. For the microbial growth process, the microbial growth rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The degree of inhibitive effect was almost the same for ethyl acetate and amyl acetate in this concentration range. The half-saturation constant K(s) values of ethyl acetate and amyl acetate were 16.26 and 12.65ppm, respectively. The maximum reaction rate V(m) values of ethyl acetate and amyl acetate were 4.08 and 3.53gCh(-1)kg(-1) packed material, respectively. Zero-order kinetic with the diffusion limitation could be regarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The inhibitive effect for ethyl acetate was more pronounced than that for AA in this concentration range. The maximum elimination capacity of ethyl acetate and amyl acetate were 82.3 and 37.93gCh(-1)m(-3) bed volume, respectively. Ethyl acetate degraded by microbial was easier than amyl acetate did.     

Biodegradation of volatile organic compounds by five fungal species

Five fungal species, Cladosporium resinae (ATCC 34066), Cladosporium sphaerospermum (ATCC 200384), Exophiala lecanii-corni (CBS 102400), Mucor rouxii (ATCC 44260), and Phanerochaete chrysosporium (ATCC 24725), were tested for their ability to degrade nine compounds commonly found in industrial off-gas emissions. Fungal cultures inoculated on ceramic support media were provided with volatile organic compounds (VOCs) via the vapor phase as their sole carbon and energy sources. Compounds tested included aromatic hydrocarbons (benzene, ethylbenzene, toluene, and styrene), ketones (methyl ethyl ketone, methyl isobutyl ketone, and methyl propyl ketone), and organic acids ( n-butyl acetate, ethyl 3-ethoxypropionate). Experiments were conducted using three pH values ranging from 3.5 to 6.5. Fungal ability to degrade each VOC was determined by observing the presence or absence of visible growth on the ceramic support medium during a 30-day test period. Results indicate that E. lecanii-corni and C. sphaerospermum can readily utilize each of the nine VOCs as a sole carbon and energy source. P. chrysosporium was able to degrade all VOCs tested except for styrene under the conditions imposed. C. resinae was able to degrade both organic acids, all of the ketones, and some of the aromatic compounds (ethylbenzene and toluene); however, it was not able to grow utilizing benzene or styrene under the conditions tested. With the VOCs tested, M. rouxiiproduced visible growth only when supplied with n-butyl acetate or ethyl 3-ethoxypropionate. Maximum growth for most fungi was observed at a pH of approximately 5.0. The experimental protocol utilized in these studies is a useful tool for assessing the ability of different fungal species to degrade gas-phase VOCs under conditions expected in a biofilter application.     

Microbial growth on 2-bromobutane

A member of the genus Arthrobacter was isolated which grew at the expense of 2-bromobutane as sole source of carbon and energy. Evidence is presented which suggests that the initial conversion of 2-bromobutane to 2-butanol is a spontaneous chemical hydrolysis and not mediated by the organism. Further evidence from oxygen consumption experiments indicates that 2-bromobutane is oxidized through 2-butanol, methyl ethyl ketone, ethyl acetate to acetate and ethanol. Results of experiments with cells grown on pathway intermediates reveal that the enzymes necessary for the oxidation of 2-butanol, methyl ethyl ketone, ethyl acetate, ethanol and acetaldehyde are not coordinately, but individually induced by their respective substrates.     

Odoriferous compounds from the flowers of the conifers Picea abies,pinus sylvestris and Larix sibirica

A GC/MS analysis of the volatile constituents from the flowers of Norway Spruce, Picea abies, has been carried out. The volatile constituents of the female flowers were distinctly different from those of the male flowers and the twigs. Characteristic constituents are methyl and ethyl benzoate, methyl and ethyl salicylate, methyl and ethyl butanoate, borneol and bornyl acetate. In the scent from the male flowers we could only detect the same monoterpenes as in the twigs. In Larix sibirica methyl benzoate, methyl salicylate, borneol and bornyl acetate were detected in the female flowers and, in the female flowers of Pinus sylvestris, methyl salicylate was found.     

Transient-state behavior of a biofilter removing mixtures of vapors of MEK and MIBK from air

In the work reported here, selected aspects of the dynamic behavior of biofilters for waste air treatment have been investigated. Emphasis was placed on transient state elimination of mixtures of methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) vapors and on explanation of the observed phenomena. The initial startup, the response of the biofilter to step changes in the pollutant loadings, responses to pollutant pulses, restarting after starvation, and the influence of step changes in gaseous phase oxygen partial pressure are presented and discussed. (c) 1996 John Wiley & Sons, Inc.     

Biofiltration of paint solvent mixtures in two reactor types: overloading by hydrophobic components

Steady-state performance characteristics of a trickle bed reactor (TBR) and a biofilter (BF) in loading experiments with increasing toluene/xylenes inlet concentrations while maintaining a constant loading rate of hydrophilic components (methyl ethyl and methyl isobutyl ketones, acetone, and n-butyl acetate) of 4 g m⁻³ h⁻¹ were evaluated and compared, along with the systems’ dynamic responses. At the same combined substrate loading of 55 g m⁻³ h⁻¹ for both reactors, the TBR achieved more than 1.5 times higher overall removal efficiency (RE_W) than the BF. Increasing the loading rate of aromatics resulted in a gradual decrease of their REs. The degradation rates of acetone and n-butyl acetate were also inhibited at higher loads of aromatics, thus revealing a competition in cell catabolism. A step-drop in loading of aromatics resulted in an immediate increase of RE_W with variations in the TBR, while the new steady-state value in the BF took 6–7 h to achieve. The TBR consistently showed a greater performance than BF in removing toluene and xylenes. Increasing the loading rate of aromatics resulted in a gradual decrease of their REs. The degradation rates of acetone and n-butyl acetate were also lower at higher OL_AROM, revealing a competition in the cell catabolism. The results obtained are consistent with the proposed hypothesis of greater toxic effects under low water content, i.e., in the biofilter, caused by aromatic hydrocarbons in the presence of polar ketones and esters, which may improve the hydrocarbon partitioning into the aqueous phase.     

Induction of chromosome loss by mixtures of organic solvents including neurotoxins

Twenty-three aprotic polar solvents - 3 nitriles, 8 organic esters, 10 ketones and 2 lactones - and LiCl were tested in combination with propionitrile alone or a mixture of ethyl acetate and propionitrile for the induction of mitotic chromosome loss in the D61.M strain of the yeast Saccharomyces cerevisiae. Propionitrile and ethyl acetate are very potent inducers of chromosome loss. Mixtures of propionitrile and ethyl acetate induced chromosome loss at much higher frequencies than was observed with the pure chemicals. To test the potentiating effects of propionitrile or mixtures of propionitrile with ethyl acetate on other chemicals, they were used in concentrations that were at or below the level for induction of chromosome loss. Twenty chemicals when tested in pure form were negative or only marginally active in the test for chromosome loss. Except for amyl propionate and benzyl acetate, the same chemicals showed strong induction in combination treatments with the potentiating chemicals. All the ketones including the neurotoxic methyl ethyl ketone, 2-hexanone and 2.5-hexanedione induced high frequencies of chromosome loss. Only methyl ethyl ketone is capable of inducing high levels of chromosome loss when tested in the pure form at much higher concentrations. 1-Methyl-2-pyrrolidinone and gamma-valerolactone had previously been shown to induce chromosome loss only when the treatment at a growth-supporting temperature was interrupted by a cold shock within a narrow range of low temperatures which prevented growth. Both gave very strong induction in combination treatment performed at a continuous growth-supporting temperature. LiCl is a weak inducer of chromosome loss: strong induction can be achieved in combination treatments.     

Aneuploidy-inducing chemicals in yeast evaluated by the micronucleus test

Chinese hamsters were exposed to acetone, methyl ethyl ketone, ethyl acetate and 2-methoxy ethyl acetate, known to be strong inducers of aneuploidy in the yeast Saccharomyces cerevisiae. All solvents yielded negative results in the micronucleus test, whereas the vinca alkaloid vindesine--used as a positive control substance--proved to act as a spindle poison in mammals in vivo.     

Synthesis of aspartame precursor with an immobilized thermolysin in mixed organic solvents

N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester, a precursor of the synthetic sweetener, aspartame, was synthesized from N-(benzyloxycarbonyl)-L-aspartic acid and L-phenylalanine methyl ester with an immobilized thermolysin (EC 3.4.24.4) in the mixed organic solvent system of tert-amyl alcohol and ethyl acetate. A mixed solvent consisting of tert-amyl alcohol and ethyl acetate at a ratio of 33:67 (v/v) was found to be the most suitable with respect to synthetic rate and stability of the immobilized enzyme. The reaction continued to proceed quite successfully in a column reactor at 40 degrees C and at a space velocity of 3.6 h(-1) with a yield of 99%, using 40 mM Z-Asp and 200 mM PheOMe dissolved in the mixed solvent as the substrate. (c) 1995 John Wiley & Sons, Inc.     

Investigations of aneuploidy-inducing chemical combinations in Saccharomyces cerevisiae

For several years we have been investigating combinations of chemicals for their ability to induce aneuploidy. Earlier published results indicated that combinations of certain chemicals showed a potentiation effect while other combinations did not. We have continued to explore this phenomenon and report additional findings in this communication. Combinations of ethyl acetate and methyl ethyl ketone showed a potentiation effect as did 1-methyl-2-pyrrolidinone-nocodazole combinations. Combinations that did not show a potentiation effect were 2-pyrrolidinone-nocodazole and 1-methyl-2-pyrrolidinone-ethyl acetate. We also found that nocodazole, which is a potent inducer of aneuploidy in yeast extract-peptone-dextrose (YEPD) medium but not in synthetic complete (SC) medium, showed a potentiation effect with ethyl acetate in SC medium. This effect in SC medium is similar to that previously reported for nocodazole with ethyl acetate in YEPD medium. When nocodazole was dissolved in 1-methyl-2-pyrrolidinone as a concentrated stock solution, a potentiation effect occurred even at low concentrations of the solvent.     

Treatment of MEK and toluene mixtures in biofilters: effect of operating strategy an performance during transient loading

In recent years, biofiltration has been increasingly applied as an air pollution control technology to minimize or eliminate emissions of volatile organic compounds from industrial sources and environmental remediation activities. Although the ability of this technology to maintain high removal efficiency during relatively steady loading conditions has been well established for many waste streams, relatively little research has focused on development of operating strategies that could improve treatment performance during transient loading conditions typical of industrial operations. In the research described herein, two operating strategies were evaluated over a period of 295 days in biofilters treating a model waste gas stream containing a two-component mixture of methyl ethyl ketone (MEK) and toluene. One biofilter was operated as a sequencing batch biofilter (SBB), and the other was operated as a conventional continuous-flow biofilter (CFB). During "normal" steady loading conditions, the model waste stream contained MEK concentrations ranging from 80 to 89 ppmv and toluene concentrations ranging from 28 to 30 ppmv. Both biofilter operating strategies resulted in stable long-term performance with greater than 99% contaminant removal during these normal loading conditions. On a regular basis, the influent MEK and toluene concentrations were temporarily increased to five times the normal influent concentration for the duration of 1 h to test performance during transient "shock loading" conditions. Biofilter performance during the model shock loading conditions demonstrate that SBB operating strategies can result in superior treatment in two important areas: (1) overall mass of contaminants removed and (2) minimum instantaneous removal efficiency.     

Extraction with methyl tert-butyl ether overcomes erratic elution patterns of 6-keto-prostaglandin F1 alpha on high pressure liquid chromatography

Solvent extraction of 6-keto-PGF1 alpha from aqueous solutions with ethyl acetate was found to result in variable and irreproducible elution patterns, when the extracts were subjected to high pressure liquid chromatography. These problems could not be resolved satisfactorily by using ethyl acetate from different suppliers, nor by changing acids or pH for acidification. After a number of unsuccessful attempts to resolve this problem, we found that variable and irreproducible elution patterns could be avoided by using methyl t-butyl ether as extraction solvent.     

STUDIES ON ENZYME ACTION : XXXV. LIPASE ACTIONS OF EXTRACTS OF TISSUES OF RABBITS AT DIFFERENT AGES.

The ester-hydrolyzing actions of extracts of a number of tissues of rabbits of different ages were studied under comparable conditions. The ages of the rabbits ranged from 8 days before birth to 2162 days. The esters used included phenyl acetate, glyceryl triacetate, methyl butyrate, benzyl acetate, methyl acetate, ethyl acetate, ethyl butyrate, methyl benzoate, ethyl benzoate, and isobutyl acetate. The following tissues were studied: kidney, liver, lung, skin, leg muscle, heart muscle, brain, spleen, stomach, and small intestine. The results, as in previous communications, are presented in the form of plots for the relative enzyme actions, and in tables for the absolute actions. The changes in the curves of the relative actions as the rabbits became older are considered in some detail. The relations between the embryonic state of certain tissues, as shown by their enzyme actions, and the adult state, are described, and compared with their physiological behavior. The probable reversion to a type approaching the embryonic for the oldest rabbits studied is indicated with some of the tissues. The changes in the absolute enzyme actions of the tissues as the rabbits became older are also discussed. The absolute actions do not form as regular a progression as do the relative actions but, at the same time, show marked regularities with increasing age of the rabbits.     

Synthesis of dipeptide precursors with an immobilized thermolysin in ethyl acetate

N-(Benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (Z-AspPheOMe), a precursor of the aspartame, and N-(benzyloxycarbonyl)-L-phenylalanyl-Lphenylalanine methyl ester (Z-PhePheOMe) were synthesized from the respective amino acid derivatives with an immobilized thermolysin (EC 3.4.24.4) in ethyl acetate. Various factors affecting the synthesis of these dipeptide precursors were clarified. The initial synthetic rate was the highest at the water content of 3.5% for both reactions. The substrate concentration dependencies of the initial synthetic rate of Z-AspkPheOMe and Z-PhePheOMe with the immobilized enzyme in ethyl acetate were different from those in an aqueous buffer solution saturated with ethyl acetate but similar to those in the aqueous/organic biphasic system using the free enzyme. Particularly, the initial synthetic rate of Z-AspPhOMe increased in order higher than first order with respect to the concentration of L-phenylalanine methyl ester (PheOMe), whereas it decreased sharply with the concentration of N-(benzyloxycarbonyl)-L-aspartic acid (Z-Asp). Such kinetic behavior could be explained by regarding the inside of the immobilized enzyme as being a biphasic mode composed from the organic phase and aqueous phase where the enzymatic reaction takes place. The reaction in the aqueous/organic biphasic system using the free enzyme could be simulated by taking into consideration the partition of the substrate and the initial rate of synthesis in the aqueous buffer saturated with ethyl acetate. Based on this analysis, the rate of reaction with the immobilized enzyme in ethyl acetate could also be predicted. Z-AsPheOMe and Z-PhePheOMe were synthesized by the fed-batch method where the acid component of the substrate was intermittently added during the course of reaction and by the batch method. In the synthesis of Z-AspPheOMe, the synthetic rate and maximum yield of reaction as well as the stability of the immobilized enzyme were higher in the fed-batch reaction than those in the batch reaction. In the synthesis of Z-PhePheOMe, the results obtained by both methods were similar. (c) 1994 John Wiley & Sons, Inc.     

榅桲的化学成分及其挥发油的GC-MS分析

采用常规水蒸气蒸馏法提取出榅桲挥发油,经气相色谱／质谱联用方法分析,分离鉴定出18种成分,主要成分有乙酸十二酯、环壬烷酸乙酯、14-十五碳烯酸、7,10,13-十二烷三烯酸甲酯、4．葵烯酸乙酯和5．甲基壬酸乙酯,并用化学方法分析了榅桲的化学成分。     

Effects of chemical combinations on the induction of aneuploidy in Saccharomyces cerevisiae

Nocodazole, ethyl acetate, acetone and methyl ethyl ketone all are known to induce aneuploidy. Treatment of yeast strain D61.M with mixtures containing ineffective low levels of nocodazole and ineffective low levels of these solvents was highly effective in inducing aneuploidy. Ineffective low levels of nocodazole mixed with ineffective low levels of methyl 2-benzimidazolecarbamate also gave elevated frequencies of aneuploidy. Dimethyl formamide, a solvent that does not induce aneuploidy, mixed with low levels of nocodazole gave no increase in aneuploidy frequency above those levels seen in controls.     

Dynamics in Polysaccharide Glasses and Their Impact on the Stability of Encapsulated Flavors

The aim of this work is to examine the correlation between measured instability of model flavor compounds in glassy matrices with the calorimetric relaxation times of the matrices. Spray-dried carbohydrate matrices were chosen as the model compounds for this study. Enthalpy relaxation times were determined for spray-dried carbohydrate matrices using differential and isothermal calorimetric methods. The losses of the volatile methyl acetate, ethyl acetate and limonene, as well as formation of limonene oxidation products, were measured by gas chromatography. Storage conditions were 30 and 40 °C, with samples equilibrated with 11, 23, 33 and 43 % RH at each temperature. A comparison of the relaxation times for temperatures below Tg was made using Modulated DSC (MDSC) and a Thermal Activity Monitor (TAM). TAM yields significantly lower values for relaxation times implying that it is capturing some of the faster dynamics as well as dynamics that are activated near Tg. However, plots of relaxation times as determined by both techniques versus temperature appear to converge at Tg. An increase in the relative humidity results in moderately higher loss of volatiles (methyl acetate, ethyl acetate and limonene) and greater oxidation rates. In general, there is a good correlation between relaxation time and stability, with greater enthalpy relaxation time associated with better stability. Enthalpy relaxation time appears to be a useful predictor of stability for both loss of volatiles and oxidation of limonene.