Biodegradation of 2-Chlorobenzoic Acid by Enterobacter cloacae: Growth Kinetics and Effect of Growth Conditions

Enterobacter cloacae was originally isolated from soil irrigated with wastewater on the basis of its ability to grow with linear alkylbenzene sulfonate (LAS) as the sole source for carbon and energy. The isolated bacterium was grown in batch cultures using a 2-chlorobenzoic acid (2-CBA)-containing minimal salt medium (MSM). 2-CBA was found to be the sole source for carbon and energy. 2-CBA inhibited the growth rate with a maximum concentration of 10 mM, after which no growth occurred. The Haldane model was used to predict the specific growth rate concentration data. 2-CBA degradation by starved E. cloaca cells was faster than that of nonstarved cells. The maximum growth rates on 2-CBA (2 mM) for starved and nonstarved cells reached only 0.34 and 0.28 h^?1, respectively. Glucose, lactose, sucrose, maltose, succinic acid, and mannitol as additional carbon sources at a fixed concentration (0.2%) caused the degradation rate of 2-CBA to proceed faster at ranges between 1.08- and 1.5-fold higher than that of the control. In contrast, using only fructose and sorbitol as the carbon sources showed catabolic repression of the degradation activity of 2-CBA by E. cloaca cells, although their cell mass was improved. All nitrogen sources supplied caused an increase in cell mass, whereas only lysine, alanine, glutamine, casein, and yeast extract caused a decrease in the degradation rate of 2-CBA, with a range between 12% and 28%. The activity of C120 could be detected in a crude extract of E. cloacae cells, indicating that the chloroaromatic ring fission occurs through the ortho pathways, not through the meta pathways. The data showed that different initial cell (inocula) densities did not affect the induction time for 2-CBA degradation. However, doubling the initial cell densities reduced the time required for reaching the complete degradation. 2-CBA degradation was optimally achieved at a 37°C incubation temperature and a pH of 7.5.     

Metabolism of meta- or/and para-chlorinated benzoic acids by the crude extract of Alcaligenes sp. strain CPE3 grown on 3,4-dichlorobenzoic acid

Summary A crude extract of Alcaligenes sp. CPE3 strain grown on 3,4-dichlorobenzoic acid metabolised 3- and 4-chlorobenzoic acid by reactions requiring O₂ and NADH, and 3,4-dichlorobenzoic acid by a reaction requiring O₂, NADH, FAD and FMN. The specific activity of the extract vs. 3-chlorobenzoic acid was described by the Michaelis-Menten kinetics, that vs. 4-chlorobenzoic acid was described by a substrate inhibitory kinetics and that vs. 3,4-dichlorobenzoic acid exhibited a two-peaked profile.     

Partial Purification and Characterization of A Novel Histidine Decarboxylase from Enterobacter aerogenes DL-1

Histidine decarboxylase (HDC) from Enterobacter aerogenes DL-1 was purified in a three-step procedure involving ammonium sulfate precipitation, Sephadex G-100, and DEAE-Sepharose column chromatography. The partially purified enzyme showed a single protein band of 52.4 kD on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH for HDC activity was 6.5, and the enzyme was stable between pH 4 and 8. Enterobacter aerogenes HDC had optimal activity at 40°C and retained most of its activity between 4 and 50°C. HDC activity was reduced in the presence of numerous tested compounds. Particularly with SDS, it significantly (p < 0.01) inhibited enzyme activity. Conversely, Ca²⁺ and Mn²⁺ showed prominent activation effects (p < 0.01) with activity increasing to 117.20% and 123.42%, respectively. The Lineweaver–Burk plot showed that K _m and V _max values of the enzyme for L-histidine were 0.21 mM and 71.39 µmol/min, respectively. In comparison with most HDCs from other microorganisms and animals, HDC from E. aerogenes DL-1 displayed higher affinity and greater reaction velocity toward L-histidine.     

Two succinate uptake systems inBradyrhizobium japonicum

Succinate uptake inBradyrhizobium japonicum 61-A-101 has a biphasic kinetic, indicating the presence of a high-and low-affinity uptake system. The apparent K_M data are 2.4 M (high-affinity system) and 172 M (low-affinity system). ForEnterobacter aerogenes NCTC 10006, only one uptake system for succinate was found with an apparent K_M of 80 M. InBradyrhizobium japonicum andEnterobacter aerogenes, succinate uptake is carrier mediated and constitutive. 2,4-Dinitrophenol and cyanide severely inhibit uptake, whereas arsenate inhibits only to a lesser extent. In both strains, fumarate is also transported by the succinate uptake system. Glucose has significant effects on succinate uptake or metabolism inEnterobacter aerogenes, but not inBradyrhizobium japonicum.     

Regioselective carboxylation of catechol by 3,4-dihydroxybenzoate decarboxylase of <Emphasis Type="Italic">Enterobacter cloacae</Emphasis> P

3,4-Dihydroxybenzoate decarboxylase in Enterobacter cloacae P241 was induced by adding 3,4-dihydroxybenzoic acid, 3-hydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid or 4-acetamidobenzoic acid to the culture medium. After stabilizing the enzyme activity by adding 5 mM dithiothreitol and 20 mM Na₂S₂O₃ to a cell-free extract, catechol at 50 mM was carboxylated in the presence of 3 M KHCO₃ to 3,4-dihydroxybenzoic acid with a molar conversion ratio of 28% after 14 h at 30°C.     

Conjugative plasmid coding for the metabolism of 2-chlorobenzoic acid byPseudomonas aeruginosa

Summary A 2-chlorobenzoic acid (2-CBA) utilizing strain ofPseudomonas aeruginosa (B₁₆) has been isolated from soil by enrichment with 2-CBA. The trait for utilization of 2-CBA as sole source of carbon and energy was lost spontaneously and by treatment with growth-limiting concentration of mitomycin C. Genes coding for 2-CBA catabolism are transferrable to 2-CBA^– variants through conjugation.

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Code plasmidique conjugué du métabolisme de l'acide 2-chlorobenzoïque

Résumé Une souche dePseudomonas aeruginosa (B₁₆) utilisant l'acide 2-chlorobenzoïque (2-CBA) a été isolée du sol par enrichissement sur le 2-CBA. L'aptitude à utiliser le 2-CBA comme seule source de carbone et d'énergie a été perdue spontanément et par traitement avec une concentration limitant la croissance de mitomycine-C. Les gènes codant pour le catabolisme du 2-CBA sont transférables aux variants 2-CBA^– par conjugaison.

     

Catechol(amine)s as probes of lactoperoxidase catalytic site structure: spectroscopic and modeling studies

 Binding affinities to lactoperoxidase (LPO) of a homologous series of substituted catechol(amine)s [such as catechol, 4-methylcatechol, 3,4-dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, 3-(3,4-dihydroxyphenyl)propionic acid; dopamine, noradrenaline, adrenaline;l-3,4-dihydroxyphenylalanine] were studied by UV-visible spectroscopy and docking simulations. Dissociation constant (K _d) values were calculated by direct fitting of the experimental data and fall in a range of 3–95 mM. Thermodynamic parameters are comparable with those reported for the interaction of LPO with p-substituted phenols, suggesting a similar general mode of binding. Furthermore, the relative contributions to binding energy, described by the unimolecular constant K _u, show that interaction between protein and ligands originates from a relatively large number of groups. Docking and molecular dynamics simulations, in agreement with experimental evidence, predict that the substrate is localized into the access channel in the vicinity of heme distal pocket. This channel is characterized by a hydrophobic patch (six Phe residues) and by a charged contribution (two Glu and one His residues). All of the substrates, except caffeic acid, may approach the protein active site. Positively charged Arg372 acts as a gate above the heme distal pocket and seems to address substrate orientation in relation to the side-chain terminal group. Received: 4 June 1998 / Accepted: 1 October 1998     

Influence of organic and inorganic growth supplements on the aerobic biodegradation of chlorobenzoic acids

The effect of yeast extract and its less complex substituents on the rate of aerobic dechlorination of 2-chlorobenzoic acid (2-ClBzOH) and 2,5-dichlorobenzoic acid (2,5-Cl₂BzOH) by Pseudomonas sp. CPE2 strain, and of 3-chlorobenzoic acid (3-ClBzOH), 4-chlorobenzoic acid (4-ClBzOH) and 3,4-dichlorobenzoic acid (3,4-Cl₂BzOH) by Alcaligenes sp. CPE3 strain were investigated. Yeast extract at 50 mg/l increased the average dechlorination rate of 200 mg/l of 4-ClBzOH, 2,5-Cl₂BzOH, 3,4-Cl₂BzOH, 3-ClBzOH and 2-ClBzOH by about 75%, 70%, 55%, 7%, and 1%, respectively. However, in the presence of yeast extract the specific dechlorination activity of CPE2 and CPE3 cells (per unit biomass) was always lower than without yeast extract, although it increased significantly during the exponential growth phase. When a mixed vitamin solution or a mixed trace element solution was used instead of yeast extract the rate of 4-ClBzOH dechlorination increased by 30%–35%, whereas the rate of 2,5-Cl₂BzOH and 3,4-Cl₂BzOH dechlorination increased by only 2%–10%. The presence of vitamins or trace elements also resulted in a specific dechlorination activity that was generally higher than that observed for the same cells grown solely on chlorobenzoic acid. The results of this work indicate that yeast extract, a complex mixture of readily oxidizable carbon sources, vitamins, and trace elements, enhances the growth and the dechlorination activity of CPE2 and CPE3 cells, thus resulting in an overall increase in the rate of chlorobenzoic acid utilization and dechlorination.     

Purification, characterization, and gene cloning of 4-hydroxybenzoate decarboxylase of Enterobacter cloacae P240

We found the occurrence of 4-hydroxybenzoate decarboxylase in Enterobacter cloacae P240, isolated from soils under anaerobic conditions, and purified the enzyme to homogeneity. The purified enzyme was a homohexamer of identical 60 kDa subunits. The purified decarboxylase catalyzed the nonoxidative decarboxylation of 4-hydroxybenzoate without requiring any cofactors. Its K _m value for 4-hydroxybenzoate was 596 μM. The enzyme also catalyzed decarboxylation of 3,4-dihydroxybenzoate, for which the K _m value was 6.80 mM. In the presence of 3 M KHCO₃ and 20 mM phenol, the decarboxylase catalyzed the reverse carboxylation reaction of phenol to form 4-hydroxybenzoate with a molar conversion yield of 19%. The K _m value for phenol was calculated to be 14.8 mM. The gene encoding the 4-hydroxybenzoate decarboxylase was isolated from E. cloacae P240. Nucleotide sequencing of recombinant plasmids revealed that the 4-hydroxybenzoate decarboxylase gene codes for a 475-amino-acid protein. The amino acid sequence of the enzyme is similar to those of 4-hydroxybenzoate decarboxylase of Clostridium hydroxybenzoicum (53% identity), VdcC protein (vanillate decarboxylase) of Streptomyces sp. strain D7 (72%) and 3-octaprenyl-4-hydroxybenzoate decarboxylase of Escherichia coli (28%). The hypothetical proteins, showing 96–97% identities to the primary structure of E. cloacae P240 4-hydroxybenzoate decarboxylase, were found in several bacterial strains.     

Kinetic Studies on the Inhibition of GABA-T by γ-Vinyl GABA and Taurine

γ-Aminobutyric acid transaminase (GABA-T, EC 2.6.1.19) is a pyridoxal phosphate (PLP) dependent enzyme that catalyzes the degradation of γ-aminobutyric acid. The kinetics of this reaction are studied in vitro, both in the absence, and in the presence of two inhibitors: γ-vinyl GABA (4-aminohex-5-enoic acid), and a natural product, taurine (ethylamine-2-sulfonic acid). A kinetic model that describes the transamination process is proposed. GABA-T from Pseudomonas fluorescens is inhibited by γ-vinyl GABA and taurine at concentrations of 51.0 and 78.5?mM. Both inhibitors show competitive inhibition behavior when GABA is the substrate and the inhibition constant (K_i) values for γ-vinyl GABA and taurine were found to be 26±3?mM and 68±7?mM respectively. The transamination process of α-ketoglutarate was not affected by the presence of γ-vinyl GABA, whereas, taurine was a noncompetitive inhibitor of GABA-T when α-ketoglutarate was the substrate. The inhibition dissociation constant (K_ii) for this system was found to be 96±10?mM. The Michaelis-Menten constant (K_m) in the absence of inhibition, was found to be 0.79±0.11?mM, and 0.47±0.10?mM for GABA and α-ketoglutarate respectively.     

Study of the photodegradation of 2-chlorobenzoic acid by TiO2 and the effects of eutrophicated water on the reaction

The photodegradation of 2-chlorobenzoic acid (2-CBA) in suspensions of TiO₂ was examined under different operational parameters. The optimal condition could be obtained through the experiment, i.e. that the concentration of 2-CBA was 30 mg/L and the dosing quantity of TiO₂ was 0.01 g under UV light in the case of pH 3.5. Above reaction process was in accordance with first order kinetics model. The influence on photocatalytic degradation caused by typical anions in eutrophicated water body such as NO₃⁻ and H₂PO₄⁻ was explored in this work, which revealed that both two anions had inhibitory effect on the degradation process. In addition, alcohol was introduced into the process to identify the degradation mechanism of 2-CBA with TiO₂, and the reaction route of 2-CBA could be predicted through the analysis on the intermediate.     

Investigation of the Effects of Some Drugs and Phenolic Compounds on Human Dihydrofolate Reductase Activity

Dihydrofolate reductase (DHFR) plays a fundamental role in cellular metabolism and cell growth. Inhibition of this enzyme will cause a decrease in the amount of folate that occurs in many metabolic processes, and the deficiency of which may cause various diseases. This study investigated the effects of some drugs and phenolic compounds on DHFR activity in vitro. To determine the inhibitory effect of compounds, enzyme activity was measured with a final concentration of an inhibitor ranging from 10 μM to 51 mM. DHFR was inhibited effectively by naringin, ferulic acid, and levofloxacin with IC₅₀ values under 660 μM. Syringic acid, cefepime, ceftizoxime, cefazolin, ceftriaxone, and ceftazidime exhibited inhibitory effects on the enzyme activity with IC₅₀ values in the range of 3.840–30.224 mM. K_i constants were calculated using the Cheng–Prusoff equation. K_i constants calculated in the range of 0.009–2.024 mM with respect to nicotinamide adenine dinucleotide phosphate oxidase (NADPH) and in the range of 0.060–5.830 mM about FH₂.     

Biosynthesis and cytoplasmic accumulation of a chlorinated catechol pigment during 3-chlorobenzoate aerobic co-metabolism in Pseudomonas fluorescens

A strain of Pseudomonas fluorescens was capable of co-metabolizing 3-chlorobenzoic acid with the production of a chlorinated catechol black pigment. A peroxidase and another enzymatic activity referred to as a polyphenol oxidase were found to be involved in the oxidation of 4-chlorocatechol to 4-chloro-1,2-benzoquinone, i.e. in the production of highly reactive substrates for pigment formation. Therefore, P. fluorescens cells were seen to take an active part not only in 3-chlorobenzoate mineralization but also in overall pigment production. pH was found to be a key parameter in the regulation of the activity of P. fluorescens oxidoreductive enzymes. Ultrastructural investigations showed that electron dense granules of pigment were distributed throughout the cytoplasm of Pseudomonas fluorescens cells grown in presence of 3-chlorobenzoate, as confirmed also by Thiéry cytochemical investigations.In these cells, an extensive contraction of the cytoplasm as well as a significant damage to the cell wall after two days of incubation, suggested that pigment production caused a premature death of the cells accompanied by the leakage of the cell content. Pigment production seemed to occur mostly in the cytoplasmic context where the electron dense material accumulates until it is released in the medium after the cell lysis.Abbreviations 3-CBA 3-chlorobenzoic acid - BA benzoic acid - 4-CC 4-chlorocatechol - 3-CC 3-chlorocatechol - MBTH 3-methyl-2-benzothiazolinone hydrazone - l-DOPA l-3,4-dihydroxyphenyl-alanine - SPB sodium phosphate buffer     

Kinetics of the inhibition of acetylcholinesterase from pigeon brain by procaine hydrochloride

The kinetic parameters of the inhibition of pigeon brain acetylchlolinesterase (AChE) by procaine hydrochloride were investigated. Procaine (0·083–1·67 mM) reversibly inhibited AChE activity (15–83 percent) in a concentration dependent manner, the IC₅₀ being about 0·38 mM. The Michaelis-Menten constant (K_m) for the hydrolysis of acetylthiocholine iodide was found to be 1·53 × 10^?4 M and the V_max was 1·06 μmol min^?1 mg^?1 protein. Dixon as well as Lineweaver-Burk plots and their secondary replots indicated that the nature of the inhibition is of the linear mixed type which is considered to be a mixture of partial competitive and pure non-competitive. The values of K_i(slope) and K_i (intercepts) were estimated as 0·14 mM and 0·22 mM respectively by the primary Dixon and by the secondary replots of the Lineweaver-Burk plot. The K_i′/K_i ratio shows that procaine has a greater affinity of binding for the peripheral than for the active site.     

Influence of chlorobenzoates on the utilisation of chlorobiphenyls and chlorobenzoate mixtures by chlorobiphenyl/chlorobenzoate-mineralising hybrid bacterial strains

Chlorobenzoates (CBA) arise as intermediates during the degradation of polychlorinated biphenyls (PCBs) and some chlorinated herbicides. Since PCBs were produced as complex mixtures, a range of mono-, di-, and possibly trichloro-substituted benzoates would be formed. Chlorobenzoate degradation has been proposed to be one of the rate-limiting steps in the overall PCB-degradation process. Three hybrid bacteria constructed to have the ability to completely mineralise 2-, 3-, or 4-monochlorobiphenyl respectively, have been studied to establish the range of mono- and diCBAs that can be utilised. The three strains were able to mineralise one or more of the following CBAs: 2-, 3-, and 4-monochlorobenzoate and 3,5-dichlorobenzoate. No utilisation of 2,3-, 2,5-, 2,6-, or 3,4-diCBA was observed, and only a low concentration (0.11 mM) of 2,4-diCBA was mineralised. When the strain with the widest substrate range (Burkholderia cepacia JHR22) was simultaneously supplied with two CBAs, one that it could utilise plus one that it was unable to utilise, inhibitory effects were observed. The utilisation of 2-CBA (2.5 mM) by this strain was inhibited by 2,3-CBA (200 M) and 3,4-CBA (50 M). Although 2,5-CBA and 2,6-CBA were not utilised as carbon sources by strain JHR22, they did not inhibit 2-CBA utilisation at the concentrations studied, whereas 2,4-CBA was co-metabolised with 2-CBA. The utilisation of 2-, 3-, and 4-chlorobiphenyl by strain JHR22 was also inhibited by the presence of 2,3- or 3,4-diCBA. We conclude that the effect of the formation of toxic intermediates is an important consideration when designing remediation strategies.Abbreviations PCB Polychlorinated biphenyl - CBA Chlorobenzoate     

The non-oxidative decarboxylation ofp-hydroxybenzoic acid,gentisic acid,protocatechuic acid and gallic acid byKlebsiella aerogenes (Aerobacter aerogenes)

Klebsiella aerogenes adapted to a chemically-defined mineral salts medium with glucose orp-hydroxybenzoate as sole source of carbon and energy possessed constitutive decarboxylases for gentisate (2,5-dihydroxybenzoate), protocatechuate (3,4-dihydroxybenzoate) and gallate (3,4,5-trihydroxybenzoate) whose pH optima were respectively 5.9, 5.6 and 5.8. A decarboxylase for PHB was induced by PHB in both growing and resting cells; the induction was delayed or inhibited by chloramphenicol and by ultrasonic disruption of the bacteria. Crude ultrasonic preparations of PHB decarboxylase had an optimum pH of 6.0, a Michaelis constant of 4mm and an activation energy of 25,500 cal mole^–1 at 28 – 38 C. All four decarboxylations proceeded without O₂ and for every mole of phenolic acid decomposed one mole of CO₂ and one mole of the corresponding phenol were produced. The effects of ultrasonic disruption of the bacteria suggested that permeability barriers limited the rate of decarboxylation of PHB and 2,5-DHB but not of 3,4-DHB or 3,4,5-THB. During ultrasonic disintegration PHB and 3,4-DHB decarboxylases were retained solely by insoluble centrifugeable particles, whereas 2,5-DHB and 3,4,5-THB decarboxylases were gradually released into solution.The decarboxylation of protocatechuic acid is an essential stage in the assimilation ofp-hydroxybenzoic acid byK. aerogenes, whereas the decarboxylation ofp-hydroxybenzoate itself is an injurious side reaction.We wish to thank Mr. P. J. Wragg for technical assistance.     

Competitive growth of slow growingRhizobium japonicum against fast growingEnterobacter andPseudomonas species at low concentrations of succinate and other substrates in dialysis culture

A cultivation system with simultaneous growth of six bacterial cultures in separate bags in dialysis culture was developed. In a medium with no added carbon source (one half concentrated Hoagland solution, water deionized and distilled), cell number ofRhizobium japonicum increased during a 7 day period by a factor of 35, whereas the number ofEnterobacter aerogenes cells decreased to one half. With a concentration of 100 nM succinate as an additional carbon source in the inflow,Rhizobium japonicum 61-A-101 cell number increased by a factor of 50 during an 8 day period, whereas cell number ofEnterobacter cloacae NCTC 10005 only doubled and ofEnterobacter aerogenes NCTC 10006 decreased. At 10 mM concentration of succinate in the inflow, doubling time the twoEnterobacter strains was about 12 h, compared to about 24 h for theRhizobium japonicum strain. Varying the succinate concentration from 10 mM to 100 nM in the inflow,Rhizobium japonicum 61-A-101 surpassed theEnterobacter aerogenes strains in the growth rate between 1 mM and 100 M succinate in the inflowing medium. Three otherRhizobium japonicum strains (fix⁺ and fix^-) did grow with a similar rate as strain 61-A-101 at very low concentrations of substrate. Growth rates for the strains were confirmed by protein data per culture. Growing in competition with twoPseudomonas strains,Rhizobium japonicum RH 31 Marburg (fix^-) did overgrow alsoPseudomonas fluorescens, was however outgrown byPseudomonas putida. In utilizing low concentrations of a¹⁴C labelled organic acid (malonate), three strains ofRhizobium japonicum left 2–4 times smaller amounts of¹⁴C in the medium than two species ofPseudomonas and two species ofArthrobacter.On sabbatical leave at ANU     

Identification of Flavone Compounds in Eighteen Gramineae Species

Conditions for tryptophan synthesis from pyruvic acid, indole and NH₄Cl by Enterobacter aerogenes AHU 1540 having a high tryptophanase activity, were investigated using a reaction mixture containing 1.7% of pyruvic acid. Under optimum conditions, 16.4g/liter of tryptophan was accumulated after 24 hr of incubation.

Agaricus campestris AHU 9382 produced pyruvic acid in amounts of 22 ~ 26.5 g/liter from 5% of glucose after 3-days shaking culture. When E. aerogenes was added to this fermentation broth together with indole and NH₄Cl, pyruvic acid produced was rapidly converted to tryptophan and yields of tryptophan as high as 15 g/liter were obtained after 12 hr of incubation. Furthermore, pyruvic acid fermentation by Saccharomyces exiguus AHU 3110 or Corynebacterium sp. 37-3A could also be used as a pyruvic acid source for subsequent tryptophan production.     

Degradation of mono- and dichlorobenzoic acid isomers by two natural isolates of Alcaligenes denitrificans

Two strains of Alcaligenes denitrificans, designated BRI 3010 and BRI 6011, were isolated from polychlorinated biphenyl (PCB)-contaminated soil using 2,5-dichlorobenzoic acid (2,5-DCBA) and 2,4-DCBA, respectively, as sole carbon and energy sources. Both strains degraded 2-chlorobenzoic acid (2-CBA), 2,3-DCBA, and 2,5-DCBA, and were unable to degrade 2,6-DCBA. BRI 6011 alone degraded 2,4-DCBA. Growth of BRI 6011 in yeast extract and 2,6-DCBA induced pyrocatechase activity, but 2,6-DCBA was not degraded, suggesting the importance of an unsubstituted carbon six of the aromatic ring. Metabolism of the chlorinated substrates resulted in the stoichiometric release of chloride, and degradation proceeded by intradiol cleavage of the aromatic ring. Growth of both strains on 2,5-DCBA induced pyrocatechase activities with catechol and chlorocatechols as substrates. In contrast to dichlorobenzoic acids, growth on 2-CBA, benzoic acid, mono- and dihydroxybenzoic acids induced a pyrocatechase activity against catechol only. Although 2,4-DCBA was a more potent inducer of both pyrocatechase activities, its utilization by BRI 6011 was inhibited by 2,5-DCBA. Specific uptake rates using resting cells were highest with 2-CBA, except when the resting cells had been previously grown on 2,5-DCBA, in which case 2,5-DCBA was the preferred substrate. The higher rates of 2,5-DCBA uptake obtained by growth on that substrate, suggested the existence of a separately induced uptake system for 2,5-DCBA.     

Purpurides B and C,Two New Sesquiterpene Esters from the Aciduric Fungus Penicillium purpurogenum JS03‐21

Purpurides B and C ( 1 and 2 , resp.), two new sesquiterpene alcohol esters generated from a drimane‐type sesquiterpenoid lactone and an amino acid, together with two known analogs, berkedrimane B ( 3 ) and purpuride ( 4 ), were isolated from the aciduric fungus Penicillium purpurogenum JS03‐21. Their structures were elucidated by spectroscopic analysis, X‐ray single‐crystal diffraction, and application of Marfey's method. Compounds 1 – 4 showed modest antifungal activities against Candida albicans with MIC values in the range of 1.2–3.3 μM . Compounds 1 and 2 showed moderate antimicrobial activities against Enterobacter aerogenes and Pseudomonas aeruginosa with MIC values in the range of 1.2–2.6 μM .