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PubMed1974

Cyanide formation from oxidation of glycine of Pseudomonas species.

With whole cells of a hydrogen cyanide-producing bacterium strain C, of the genus Pseudomonas, it was found that the oxygen necessary for the oxidation of glycine to cyanide could be replaced by various artificial electron acceptors. The order of reactivity was: oxygen > phenazine methosulphate > methylene blue > 2,6-dichlorophenolindophenol > ferricyanide. Cyanide production was inhibited by pyrrolnitrin, a well-known inhibitor of many flavine enzymes. The molar ratio of added glycine to cyanide produced was found to be 1.09. With whole bacteria the apparent K(m) (glycine) for the cyanide production was found to be 5.0 x 10(-4) M.

Acridines↗
PubMed2003

Regulation of antibiotic production in root-colonizing Peudomonas spp. and relevance for biological control of plant disease.

Certain strains of fluorescent pseudomonads are important biological components of agricultural soils that are suppressive to diseases caused by pathogenic fungi on crop plants. The biocontrol abilities of such strains depend essentially on aggressive root colonization, induction of systemic resistance in the plant, and the production of diffusible or volatile antifungal antibiotics. Evidence that these compounds are produced in situ is based on their chemical extraction from the rhizosphere and on the expression of antibiotic biosynthetic genes in the producer strains colonizing plant roots. Well-characterized antibiotics with biocontrol properties include phenazines, 2,4-diacetylphloroglucinol, pyoluteorin, pyrrolnitrin, lipopeptides, and hydrogen cyanide. In vitro, optimal production of these compounds occurs at high cell densities and during conditions of restricted growth, involving (i) a number of transcriptional regulators, which are mostly pathway-specific, and (ii) the GacS/GacA two-component system, which globally exerts a positive effect on the production of extracellular metabolites at a posttranscriptional level. Small untranslated RNAs have important roles in the GacS/GacA signal transduction pathway. One challenge in future biocontrol research involves development of new strategies to overcome the broad toxicity and lack of antifungal specificity displayed by most biocontrol antibiotics studied so far.

Anti-Bacterial Agents↗
PubMed1985

Purification and properties of bromoperoxidase from Pseudomonas pyrrocinia.

A bromoperoxidase was purified and partially characterized from Pseudomonas pyrrocinia ATCC 15958, a bacterium that produces the antifungal antibiotic pyrrolnitrin. The purified enzyme preparation was homogeneous as determined by polyacrylamide gel electrophoresis and ultracentrifugation. The molecular mass of the enzyme was estimated to be 154 kDa +/- 3 kDa as determined by gel filtration and ultracentrifugation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed a single band with the mobility of a 76-kDa species. Therefore, in solution at neutral pH, bromoperoxidase exists as a dimeric species. The isoelectric point was 5.0. The prosthetic group of this procaryotic bromoperoxidase was ferriprotoporphyrin IX. The spectral properties of the native and reduced enzyme are reported. The purified enzyme showed brominating as well as peroxidase and catalase activity.

Electrophoresis, Polyacrylamide Gel↗
PubMed1997

Novel butyrolactones with antifungal activity produced by Pseudomonas aureofaciens strain 63-28.

The bacterium Pseudomonas aureofaciens 63-28 is antagonistic to several plant pathogenic fungi, including Pythium spp. The bacterium produced at least four antifungal metabolites active against Pythium ultimum and Phytophthora cryptogea when tested in culture for antifungal activity. Two of these compounds were identified as the novel butyrolactones (Z)-4-hydroxy-4-methyl-2-(1-hexenyl)-2-butenolide and (Z)-4-hydroxymethyl-2-(1-hexenyl)-2-butenolide, by using NMR and GC-MS. All compounds were different from other antibiotics produced by Pseudomonas spp., including pyoluteorin, pyrrolnitrin, and 2,4-diacetylphloroglucinol, as determined by HPLC. This is the first report of butyrolactones with antifungal activity produced by a saprophytic Pseudomonas spp.

4-Butyrolactone↗
PubMed2000

On the mechanism of action of the myxobacterial fungicide ambruticin.

The myxobacterial fungicide, ambruticin, kills the yeast, Hansenula anomala, with high efficacy (MIC 0.05 microg/ml), but only when the cells are growing. The earliest effect, observed almost immediately after the addition of the antibiotic, is a transient but substantial increase of intracellular glycerol, followed by an accumulation of triacylglycerols and free fatty acids. At about the time when free fatty acids accumulate, the cells become leaky to low molecular weight compounds. We assume that this leakage kills the cells. The mechanism of action of ambruticin thus appears to be the same as that of the phenylpyrroles, e.g., pyrrolnitrin, viz., interference with osmoregulation.

Antifungal Agents↗
PubMedDate not supplied

Chemotherapeutic agents with an imidazole moiety. III. Synthesis and microbiological activity of new 1,4-diarylimidazole and 1,4-pyrrolimidazolphenylene derivatives.

New 1,4-diarylimidazole and 1,4-pyrrolimidazol-phenylene derivatives were prepared in attempt to deepen S.A.R. study on chemotherapeutic agents with an imidazole moiety. Antimicrobial data in comparison with antifungal antibiotic pyrrolnitrin showed that all tested compounds are practically inactive against blastomycetes but some derivatives exhibited selective activity against strains of gram-negative bacteria. The results obtained are discussed on the basis of structure-activity relationships.

Anti-Bacterial Agents↗
PubMed1990

[Erythema multiforme associated with contact sensitization. Description of 6 clinical cases].

Allergic contact dermatitis generally presents itself as an eczematous eruption. However, some allergens, such as plants, exotic woods, topical medications and chemicals have been reported as causing an erythema multiforme-like eruption. We describe 6 patients, 4 women and 2 men ranging from 28 to 66 years. They showed erythematous urticarial papules, plaques and target-lesions similar to the manifestations previously reported as "erythema multiforme-like eruption". On the basis of the positive epicutaneous tests, the aetiological agents of these reactions are presumed to be Idoxuridine, textile dyes, deodorants, paraphenylenediamine and pyrrolnitrin. The clinical pattern, the histopathological features and the pathogenesis are discussed. Finally, the clinical and anamnestic criteria indicating the opportunity of performing patch tests in patients showing an atypical erythema multiforme are suggested.

Aged↗
PubMed1989

[Substances with antibacterial and antifungal activity. VI. Synthesis and microbiologic activity of new derivatives of 1,5-diarylpyrrole and 1,4-pyrrolphenylene].

New 1,5-diarylpyrrole and 1,4-pyrrolphenylene derivatives were prepared to study influence on the microbiological activity of an unsubstituted pyrrole nucleus or of a double identical molecular structure. Antimicrobial data in comparision with antifungal antibiotic pyrrolnitrin showed that all tested compounds exhibited very poor antifungal and antibacterial activity. Only some derivatives showed a selective activity against strains of Candida sp. and against strains of gram-positive or gram-negative bacteria.

Anti-Bacterial Agents↗
PubMed1989

[Substances with antibacterial and antifungal activity. VII. Synthesis and microbiologic activity of new derivatives of 1,5-diarylpyrrole].

The synthesis and antifungal activities of new 1,5-diarylpyrrole derivatives are reported. Antimicrobial data in comparison with pyrrolnitrin show that N-methylpiperazinylamides exhibit very poor activity against Candida albicans and Candida sp. while acid and ester derivatives are inactive. Vice-versa many acid or amide derivatives show interesting antibacterial activity. The results obtained are discussed on the basis of structure-activity relationships.

Anti-Bacterial Agents↗
PubMed1988

[A substance with antibacterial and antifungal activity. IV. Synthesis and microbiological activity of new 1,5-diarylpyrrole derivatives].

The synthesis and antifungal activities of new 1,5-diarylpyrrole derivatives are reported. Antimicrobial data in comparison with pyrrolnitrin show that only carboxamide derivatives exhibit satisfactory antifungal activity. By contrast all tested compounds show very poor antibacterial activity. The displacement of NO2 group from para to meta or ortho position of the aryl at C5 of the pyrrole ring affects the antimicrobial activity.

Anti-Infective Agents↗
PubMed1988

Chemotherapeutic agents with an imidazole moiety. II. Synthesis and biological activities of new 1,4-diarylimidazoles.

The synthesis, antifungal and pharmacological activities of new 1,4-diarylimidazoles are reported. Antimicrobial data in comparison with antifungal antibiotic pyrrolnitrin pointed out that the 1,4-diaryl-2-mercaptoimidazole derivatives were inactive and all 1,4-diarylimidazoles exhibited a weak antifungal activity. Some compounds showed a selective activity against strains of Candida sp. Instead pharmacological data did not evidence any significant antiinflammatory activity. The tested compounds were prepared by reacting appropriate phenacylanilines with potassium thiocyanate in acidic medium to afford 1,4-diaryl-2-mercapto imidazoles which were then transformed into title compounds by treatment with nitric acid.

Animals↗
PubMed1987

[Antibacterial and antifungal compounds. VIII. Synthesis and antifungal activity of pyrrol derivatives similar to trichostatin A].

Some p-methylbenzolpyrrole acrylic acids and related compounds were synthesized. The new pyrrole derivatives have structural features in common with trichostatin A, an antifungal antibiotic. The above acids and derivatives were tested against Candida albicans and Candida sp in comparison with miconazole, pyrrolnitrin and amphotericin B and showed very weak antifungal activities. Occasionally some activity was found against a few strains of Candida albicans and against Candida pseudotropicalis.

Antifungal Agents↗
PubMed1987

Research on antibacterial and antifungal agents. III. Synthesis and antimicrobial activity of 2-methyl-5-aryl-3-furoic acids and 2-methyl-3-imidazolylmethyl-5-aryl furans.

The synthesis and microbiological activities of 2-methyl-5-aryl-3-furoic acids and 2-methyl-3-imidazolyl-methyl-5-aryl-3-furans are reported. Antimicrobial data in comparison with pyrrolnitrin showed an interesting antifungal activity but a very poor antibacterial activity. The presence of an imidazole nucleus does not increase antifungal activity. The introduction of a substituent in the para position of the aryl at a C5 of the furan ring affects antifungal activity.

Anti-Bacterial Agents↗
PubMed1985

Antimycotic 2-alkyldithio, 2-aralkyldithio, 2-aryldithiobenzamides.

Some 2-alkyldithio, 2-aralkyldithio, 2-aryldithio benzoic acids, their methyl esters and N-monosubstituted amides were prepared and tested in vitro against Candida albicans and Trichophyton mentagrophytes. Some N-monosubstituted amides displayed activities similar to those of clotrimazole and pyrrolnitrin. Against Candida albicans, N-monosubstituted amides exhibited a generally higher activity than the corresponding N-monosubstituted amides of 2,2'-dicarboxydiphenyldisulfide.

Amides↗
PubMed1975

Effect of phenethyl alcohol and other organic substances on cellulas production.

Cellulase can be produced from growth in noncellulosic substrate if the growth rate of the producing organism is restricted. Phenethyl alcohol (PEA) is a growth inhibitor and was used to control the growth of M. verrucaria in attempts to obtain increased cellulase production. Cellulase yield was found to be increased without a restriction in growth rate when PEA was present in low concentrations (0.03% v/v). The effect was observed for other organisms but notably L. trabea, which produced considerable enzyme from a small quantity of mycelium. Here increased cellulase synthesis was concomitant with restricted growth. Other chemicals with PEA-like structure (e.g. benzyl alcohol) resulted in similar or more extensive cellulase synthesis. Of the substances tried, propyl alcohol was most effective, followed by acetone. PEA causes a swelling of cell walls and inhibits spore formation. This and other data given suggest that PEA affects the cytoplasmic membrane or the cell wall or both. Cellulase synthesis is considered to take place in the membrane and wall region of the cell.

Acetone↗
PubMed1975

Oscillations of an electrogenic pump in the plasma membrane of Neurospora.

The presence of the poky mutation in Neurospora crassa produces mitochondria which are defective in cytochromes b and aa3 but which compensate by means of an alternate, cyanide-insensitive oxidase. As previously reported (Slayman, Rees, Orchard & Slayman, J. Biol. Chem., 250:396, 1975) cyanide blockade of the poky strain carrying the partial suppressor f results in a metabolic downshift of only 56%, compared with a downshift of 98% in wild-type Neurospora; the downshift is accompanied by exponential decay of ATP in the wild type, but by an undershoot and monotonic recovery of ATP in poky f. Whereas the membrane potential declines with ATP in wild-type Neurospora, it oscillates near the resting level (ca. -- 185 mV) in poky f. Oscillations begin with a depolarizing swing of 30--100 mV, followed by slight hyperpolarization, then by 2--4 damped cycles having a frequency near 1/min. Similar oscillations arise with antimycin, salicyl hydroxamic acid, and several uncoupling agents, and depend on partial maintenance of respiration through either the defective cytochrome chain or the alternate oxidase. Small oscillations (maximally +/- 30% of the control value) in membrane conductance also occur, roughly in phase with the oscillations of membrane potential. The amplitude of these, in comparison with the nonlinearity of the normal current-voltage relationship for the membrane, strongly suggests that they arise as a secondary consequence of the voltage changes. Therefore, since it has previously been argued (Slayman, Long & Lu, J. Membrane Biol. 14:305, 1973) that most of the resting membrane potential in the organism arises from active extrusion of H+ ions, the simolest interpretation of the cyanide-induced voltage oscillations is that current through the H+ pump is modulated cyclically. The ultimate mechanism for this modulation is unresolved, but could plausible involve a metabolic feedback system, oscillations of intracellular pH, or both. In many respects the observed voltage oscillations resemble the well-known oscillations of mitochondrial H+ flux which are produced by sudden metabolic shifts.

Adenosine Triphosphate↗
PubMed2001

Microbial biosynthesis of halometabolites.

Halometabolites are compounds that are commonly found in nature and they are produced by many different organisms. Whereas bromometabolites can mainly be found in the marine environment, chlorometabolites are predominately produced by terrestrial organisms; iodo- and fluorocompounds are only produced infrequently. The halogen atoms are incorporated into organic compounds by enzyme-catalyzed reactions with halide ions as the halogen source. For over 40 years haloperoxidases were thought to be responsible for the incorporation of halogen atoms into organic molecules. However, haloperoxidases lack substrate specificity and regioselectivity, and the connection of haloperoxidases with the in vivo formation of halometabolites has never been demonstrated. Recently, molecular genetic investigations showed that, at least in bacteria, a different class of halogenases is involved in halometabolite formation. These halogenases were found to require FADH2, which can be produced from FAD and NADH by unspecific flavin reductases. In addition to FADH2, oxygen and halide ions (chloride and bromide) are necessary for the halogenation reaction. The FADH2-dependent halogenases show substrate specificity and regioselectivity, and their genes have been detected in many halometabolite-producing bacteria, suggesting that this type of halogenating enzymes constitutes the major source for halometabolite formation in bacteria and possibly also in other organisms.

Anti-Bacterial Agents↗