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PubMed1996

Hydroxylation of quinaldic acid: quinaldic acid 4-monooxygenase from Alcaligenes sp. F-2 versus quinaldic acid 4-oxidoreductases.

The N-heterocycles quinaldic acid (quinoline 2-carboxylic acid), kynurenic acid (4-hydroxyquinoline 2-carboxylic acid), 2-oxo-1,2-dihydroquinoline, and xanthine are utilized by Alcaligenes sp. F-2 as sole source of carbon and energy. Although quinoline did not serve as growth substrate, 8-hydroxy-2-oxo-1,2-dihydroquinoline and 8-hydroxycoumarin, metabolites of the 'coumarin pathway' of quinoline catabolism, were isolated from the culture fluid during growth on 2-oxo-1,2-dihydroquinoline. Contrary to Serratia marcescens 2CC-1 and Pseudomonas sp. AK-2 (Sauter et al. (1993) Biol. Chem. Hoppe-Seyler 374, 1037-1046), which possess different molybdenum-containing hydroxylases catalysing the 4-hydroxylation of quinaldic acid to kynurenic acid with incorporation of oxygen derived from water and concomitant reduction of an electron acceptor, Alcaligenes sp. F-2 contains an inducible quinaldic acid 4-monooxygenase that catalyses the very same conversion in the presence of O2 and NADH. The activity of the monooxygenase was enhanced 1.5-fold by Fe2+ ions. The extremely thermolabile enzyme (apparent molecular mass: 155 kDa) exclusively accepted quinaldic acid as substrate. The 'pseudosubstrates' menadione, 8-hydroxyquinoline, and 8-hydroxy-2-oxo-1,2-dihydroquinoline effected consumption of NADH and oxygen without being hydroxylated. Quinaldic acid 4-monooxygenase was inhibited by sulfhydryl modifying and chelating agents, and by various divalent metal ions, whereas reducing agents did not affect enzymatic activity.

Alcaligenes↗
PubMed1993

Characterization of a temperate phage hosted by Alcaligenes eutrophus strain A5.

Nineteen strains of Alcaligenes eutrophus were tested for the presence of prophages. One strain that lysed upon mitomycin C treatment produced a phage which could not form plaques on any of the strains available. DNA extracted from partially purified phage lysates was digested with various restriction enzymes which showed that the 42 kb long viral double-stranded DNA circularizes by means of cohesive ends. To our knowledge, this is the first description of a phage for the genus Alcaligenes.

Alcaligenes↗
PubMed2006

Purification and characterization of a novel caffeine oxidase from Alcaligenes species.

Alcaligenes species CF8 isolated from surface water of a lake produced a novel serine type metallo-caffeine oxidase. The optimal medium for caffeine oxidase production by this strain was (w/v) NaNO(3), 0.4%; KH(2)PO(4), 0.15%; Na(2)HPO(4), 0.05%; FeCl(3).6H(2)O, 0.0005%; CaCl(2).2H(2)O, 0.001%; MgSO(4).7H(2)O, 0.02%; glucose, 0.2%; caffeine, 0.05%, pH 7.5. The enzyme was purified to 63-fold by using ammonium sulfate precipitation, dialysis, ion exchange (diethylaminoethyl-cellulose) and gel filtration (Sephadex G-100) chromatographic techniques. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified caffeine oxidase was monomeric with a molecular mass of 65 kDa. The purified caffeine oxidase with a half-life of 20 min at 50 degrees C had maximal activity at pH 7.5 and 35 degrees C. The purified caffeine oxidase had strict substrate specificity towards caffeine (K(m) 8.94 microM and V(max) 47.62 U mg protein(-1)) and was not able to oxidize xanthine and hypoxanthine. The enzyme activity was not inhibited by para-chloromercuribenzoic acid, iodoacetamide, n-methylmaleimide, salicylic acid and sodium arsenite indicating the enzyme did not belong to xanthine oxidase family. The enzyme was not affected by Ca(+2), Mg(+2) and Na(+), but was completely inhibited by Co(+2), Cu(+2) and Mn(+2) at 1mM level. The novel caffeine oxidase isolated here from Alcaligenes species CF8 may be useful in biotechnological processes including waste treatment and biosensor development.

Alcaligenes↗
PubMed1997

Strains of Alcaligenes faecalis from clinical material.

Six strains of Alcaligenes faecalis, unusually isolated from clinical material, are described. Alcaligenes faecalis is a Gram-negative catalase- and oxidase-positive, motile rod. It is commonly found in a watery environment and is rarely isolated from humans. The clinical and laboratory characteristics of the clinical A. faecalis isolates are presented.

Adult↗
PubMed1998

Molecular cloning, sequencing and expression in Escherichia coli of the poly(3-hydroxyalkanoate) synthesis genes from Alcaligenes latus DSM1124.

Fragments of chromosomal DNA from Alcaligenes latus DSM1124 were cloned into Escherichia coli and transformants were screened for poly(D(-)-3-hydroxybutyrate) [P(3HB)] production during excess carbon supply. A plasmid harboring a 5.5-kb insert of A. latus DNA was isolated from a P(3HB)-producing bacterial colony. The insert was partially sequenced and three major open reading frames (ORFs) were found, representing the PHA synthase (phaC), beta-ketothiolase (phaA) and acetoacetyl-CoA reductase (phaB) genes. They show striking homology to the Ralstonia eutropha (formerly Alcaligenes eutrophus) phaC (71%), phaA (77%) and phaB (80%) genes, and are organized in the same way. The only major difference is the replacement of 560 nucleotides by 160 non-homologous nucleotides in the 5' region of phaC in A. latus. The phaC ORF lacks 29 amino acids at the N-terminus, compared to that of R. eutropha, and starts with a GTG codon. The transcription start points of the operon were determined. P(3HB) production of recombinant E. coli strains harboring the pha operons of A. latus DSM1124 or R. eutropha H16 was investigated. Both operons gave rise to less than 5% P(3HB) formation during exponential growth. At the end of the growth phase, the P(3HB) content reached approximately 20% of cell dry mass. Under nitrogen-depleted conditions, the A. latus pha genes gave rise to 50-52% P(3HB), compared to 33-38% for the R. eutropha pha genes. No NADH oxidase activity was detectable in A. latus, indicating an impaired respiratory pathway and a dependence on PHA synthesis for storing reduction equivalents during growth.

Acyltransferases↗
PubMed1997

[Neonatal meningitis caused by Alcaligenes xylosoxydans].

BACKGROUND: Neonatal meningitis due to Alcaligenes xylosoxydans is exceptional; its diagnosis and treatment may be difficult. CASE REPORT: A neonate born at 42 weeks of GA to a mother who worked as a nurse in an intensive care unit was admitted on day 2 for a severe infection. Her cerebrospinal (CSF) contained 1,970 white cell/mm3, polymorphonuclear in majority: direct examination failed to show any germ but the CSF and blood cultures were positive for Alcaligenes xylosoxydans, a strain that was resistant to the initially given antibiotics. The patient was given piperacillin, 300 mg/kg/d for 21 days and completely cured with a follow-up of 6 months. CONCLUSIONS: This case shows that lombar puncture can be necessary in evaluating early neonatal sepsis; it also shows usefulness of piperacillin in some cases.

Alcaligenes↗
PubMed1998

Epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans by antibacterial susceptibility testing, fatty acid analysis, PAGE of whole-cell protein and pulsed-field gel electrophoresis.

Antibacterial susceptibility testing, fatty acid analysis, protein analysis and DNA analysis of Alcaligenes xylosoxidans subsp. xylosoxidans were compared to determine the efficiency of the methods available for strain typing. Thirty isolates were investigated: 20 clinical isolates from a nonsocomial outbreak in Essen (Germany), 9 clinical isolates from sporadic nosocomial cases in Paris (France) and reference strain ATCC 2402. The highest microbiological discriminative power was exhibited by pulsed-field gel electrophoresis (PFGE) yielding nine types, followed by fatty acid methyl ester (FAME) analysis with six types, and antibacterial susceptibility testing and polyacrylamide gel electrophoresis with five types each. By combining the results of the four typing methods, 14 varieties could be differentiated. Protein analysis and fatty acid analysis failed to discriminate between isolates from Essen and Paris and the reference strain, while antibacterial susceptibility testing and DNA analysis clearly discriminated them. It is concluded that a combination of antibacterial susceptibility testing and PFGE typing is most suitable for epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans strains.

Alcaligenes↗
PubMed1974

Studies of the polysaccharide fraction from the lipopolysaccharide of Pseudomonas alcaligenes.

Studies of the lipopolysaccharide of Pseudomonas alcaligenes strain BR 1/2 were extended to the polysaccharide moiety. The crude polysaccharide, obtained by mild acid hydrolysis of the lipopolysaccharide, was fractionated by gel filtration. The major fraction was the phosphorylated polysaccharide, for which the approximate proportions of residues were; glucose (2), rhamnose (0.7), heptose (2-3), galactosamine (1), alanine (1), 3-deoxy-2-octulonic acid (1), phosphorus (5-6). The heptose was l-glycero-d-manno-heptose. The minor fractions from gel filtration contained free 3-deoxy-2-octulonic acid, P(i) and PP(i). The purified polysaccharide was studied by periodate oxidation, methylation analysis, partial hydrolysis, and dephosphorylation. All the rhamnose and part of the glucose and heptose occur as non-reducing terminal residues. Other glucose residues are 3-substituted, and most heptose residues are esterified with condensed phosphate residues, possibly in the C-4 position. Free heptose and a heptosylglucose were isolated from a partial hydrolysate of the polysaccharide. The location of galactosamine in the polysaccharide was not established, but either the C-3 or C-4 position appears to be substituted and a linkage to alanine was indicated. In its composition, the polysaccharide from Ps. alcaligenes resembles core polysaccharides from other pseudomonads: no possible side-chain polysaccharide was detected.

Alanine↗
PubMed1978

The properties of adenosine triphosphatase from exponential and synchronous cultures of Alcaligenes eutrophus H16.

The properties of Alcaligenes eutrophus ATPase (adenosine triphosphatase) were investigated by using subcellular fractions prepared from cells growing in exponential and synchronous cultures. Both the soluble and membrane-bound forms of the ATPase were inhibited non-competitively (K(i) 142mum) by Nbf-Cl (4-chloro-7-nitrobenzofurazan), whereas only the membrane-bound enzyme was inhibited (non-competitive; K(i) 750mum) by NN'-dicyclohexylcarbodi-imide. Neither the activity of the ATPase nor its sensitivity to these two inhibitors varied during exponential growth. However, marked variations in ATPase activity were observed during synchronous growth, which were characterized by maxima at approx. 0.4 and 0.9 of a cell cycle and minima at approx. 0.1 and 0.6 of a cycle. Sensitivity to Nbf-Cl and NN'-dicyclohexylcarbodi-imide also varied during the cell cycle; maximum inhibition by the former occurred at approx. 0.4 and 0.9 of a cell cycle, whereas maximum inhibition by the latter was located at approx. 0.1 and 0.6 of a cell cycle. Proton conductance by whole cells was also periodic during the cell cycle, the lowest rates occurring at approx. 0.15 and 0.55 of a cycle and the highest rates at approx. 0.4 and 0.9 of a cycle, but -->H(+)/O quotients for the oxidation of endogenous substrates remained relatively constant and indicated the presence of four proton-translocating respiratory segments throughout the cell cycle. These results are discussed in terms of ATPase and respiratory-chain structure and function during the cell cycle of Alcaligenes eutrophus.

4-Chloro-7-nitrobenzofurazan↗
PubMed2001

Characterization of (R/S)-mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid]-degrading Alcaligenes sp.CS1 and Ralstonia sp. CS2 isolated from agricultural soils.

The herbicide mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid] is widely applied to corn fields in order to control broad-leaved weeds. However, it is often detected in groundwater where it can be a persistent contaminant. Two mecoprop-degrading bacterial strains were isolated from agricultural soils through their capability to degrade (R/S)-mecoprop rapidly. 16S rDNA sequencing of the isolates demonstrated that one was closely related to the genera Alcaligenes sp. (designated CS1) and the other to Ralstonia sp. (designated CS2). Additionally, these isolates demonstrated ability to grow on other related herbicides, including 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA [4-chloro-2-methyl phenoxy acetic acid] and (R/S)-2,4-DP [2-(2,4-dichlorophenoxy)propionic acid] as sole carbon sources. tfdABC gene-specific probes derived from the 2,4-D-degrading Variovorax paradoxus TV1 were used in hybridization analyses to establish whether tfd-like genes are present in mecoprop-degrading bacteria. Hybridization analysis demonstrated that both Alcaligenes sp. CS1 and Ralstonia sp. CS2 harboured tfdA, tfdB and tfdC genes on plasmids that have approximately > 60% sequence similarity to the tfdA, tfdB and tfdC genes of V. paradoxus. It is therefore likely that tfd-like genes may be involved in the degradation of mecoprop, and we are currently investigating this further.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed1993

Nitrilase in biosynthesis of the plant hormone indole-3-acetic acid from indole-3-acetonitrile: cloning of the Alcaligenes gene and site-directed mutagenesis of cysteine residues.

Indole-3-acetic acid is the major auxin in most plants. In Cruciferae, including Brassicaceae, indole-3-acetic acid is synthesized from indole-3-acetonitrile by nitrilase, after indole-3-acetonitrile is formed from tryptophan via indole-3-acetaldoxime or indole glycosinolates as the intermediate. We cloned and sequenced the gene for nitrilase (EC 3.5.5.1), which catalyzes the hydrolysis of indole-3-acetonitrile to indole-3-acetic acid, from Alcaligenes faecalis JM3. The amino acid sequence deduced from the nucleotide sequence of the nitrilase gene shows 34.7% identity with that of Klebsiella ozaenae nitrilase. A DNA clone containing the nitrilase gene expressed the active enzyme in Escherichia coli with excellent yield. Among five cysteine residues (Cys-40, Cys-115, Cys-162, Cys-163, and Cys-218) in the Alcaligenes nitrilase, only Cys-163 was conserved at the corresponding position in the Klebsiella nitrilase. Two mutant enzymes, in which Cys-162 and Cys-163 were replaced with Asn and Ala, respectively, were constructed by site-directed mutagenesis. A 35% increase of the specific activity and a large reduction of the Km for thiophene-2-acetonitrile (which was used as a standard substrate for the nitrilase) were observed in the Cys-162-->Asn mutant enzyme. The Cys-163-->Ala mutation resulted in complete loss of nitrilase activity, clearly indicating that Cys-163 is crucial for the activity and Cys-162 could not provide the catalytic function of Cys-163.

Alcaligenes↗
PubMed2001

Cloning, sequencing and mutagenesis of the genes for aromatic amine dehydrogenase from Alcaligenes faecalis and evolution of amine dehydrogenases.

The nucleotide sequence of the aromatic amine utilization (aau) gene region from Alcaligenes faecalis contained nine genes (orf-1, aauBEDA, orf-2, orf-3, orf-4 and hemE) transcribed in the same direction. The aauB and aauA genes encode the periplasmic aromatic amine dehydrogenase (AADH) large and small subunit polypeptides, respectively, and were homologous to mauB and mauA, the genes for the large and small subunits of methylamine dehydrogenase (MADH). aauE and aauD are homologous to mauE and mauD and apparently carry out the same function of transport and folding of the small subunit polypeptide in the periplasm. No analogues of the mauF, mauG, mauL, mauM and mauN genes responsible for biosynthesis of tryptophan tryptophylquinone (the prosthetic group of amine dehydrogenases) were found in the aau cluster. orf-2 was predicted to encode a small periplasmic monohaem c-type cytochrome. No biological function can be assigned to polypeptides encoded by orf-1, orf-3 and orf-4 and mutations in these genes appeared to be lethal. Mutants generated by insertions into mauD were not able to use phenylethylamine, tyramine and tryptamine as a source of carbon and phenylethylamine, 3'-hydroxytyramine (dopamine) and tyramine as a source of nitrogen, indicating that AADH is the only enzyme involved in utilization of primary amines in A. faecalis. AADH genes are present in Alcaligenes xylosoxydans subsp. xylosoxydans, but not in other beta- and gamma-proteobacteria. Phylogenetic analysis of amine dehydrogenases (MADH and AADH) indicated that AADH and MADH evolutionarily diverged before separation of proteobacteria into existing subclasses.

Alcaligenes↗
PubMed2003

The nomenclatural type of the genus Deleya and the consequences of Deleya aesta and Alcaligenes aquamarinus being synonyms.

The genus Deleya was created to encompass a number of marine organisms that had previously been classified in diverse genera. Deleya aesta was designated as the type species of the genus. Subsequent work indicated that Deleya aesta, Alcaligenes aquamarinus and Alcaligenes faecalis subsp. homari were heterotypic synonyms. Consequently, Akagawa & Yamasato (Int J Syst Bacteriol 39, 462-466, 1989) concluded that, based on Rules 23a and 51b of the Bacteriological Code (1975 Revision), the oldest legitimate species epithet was aquamarinus and the type species of the genus Deleya should therefore be changed to Deleya aquamarina. Dobson & Franzmann (Int J Syst Bacteriol 46, 550-558, 1996) concluded that it was not possible to distinguish between members of the genus Deleya and members of the genus Halomonas Vreeland et al. 1980, leading them to transfer members of the genus Deleya to the genus Halomonas and resulting in the creation of a new combination, Halomonas aquamarina. Closer examination of some of these changes indicates that they are not all in accordance with the Rules of the Bacteriological Code (1975 or 1990 Revisions).

Alcaligenes↗
PubMed2005

Reclassification of Alcaligenes latus strains IAM 12599T and IAM 12664 and Pseudomonas saccharophila as Azohydromonas lata gen. nov., comb. nov., Azohydromonas australica sp. nov. and Pelomonas saccharophila gen. nov., comb. nov., respectively.

The aim of this study was to clarify the taxonomic position of the nitrogen-fixing and hydrogen-oxidizing bacteria Alcaligenes latus strains IAM 12599T, IAM 12664 and IAM 12665 and Pseudomonas saccharophila IAM 14368T. It was found that the type strain of Alcaligenes latus, IAM 12599T, showed 99 x 9 and 96 x 1 % 16S rRNA gene sequence similarity to strains IAM 12665 and IAM 12664, respectively. A comparison using DNA-DNA hybridization suggested that strains IAM 12599T and IAM 12665 belong to a single species (89 x 7 %) and that strain IAM 12664 (35 x 1 %) forms a separate species. The phenotypic characteristics also support the conclusion that these bacteria should be identified as two species of a new genus: Azohydromonas lata gen. nov., comb. nov. (type strain IAM 12599T=DSM 1122T=LMG 3321T=ATCC 29712T; reference strain IAM 12665=DSM 1123=LMG 3325=ATCC 29714) and Azohydromonas australica sp. nov. (type strain IAM 12664T=DSM 1124T=LMG 3324T=ATCC 29713T). Pseudomonas saccharophila IAM 14368T was found to be closely related to the phototrophic bacterium Roseateles depolymerans, with 96 x 8 % 16S rRNA gene sequence similarity, but the two bacteria are quite different with respect to their metabolism and some significant phenotypic characteristics, suggesting that they cannot be included in a single genus. Further studies on their nifH gene sequences, G+C content of the DNA and cellular fatty acid composition confirm that Pseudomonas saccharophila should be reclassified: the name Pelomonas saccharophila gen. nov., comb. nov. is proposed, with the type strain IAM 14368T (=LMG 2256T=ATCC 15946T).

Alcaligenes↗
PubMed1989

Comparison of the NH2-terminal amino acid sequences of the four non-identical subunits of the NAD-linked hydrogenases from Nocardia opaca 1b and Alcaligenes eutrophus H16.

The cytoplasmic, NAD-linked hydrogenase of the Gram-positive hydrogen-oxidizing bacterium Nocardia opaca 1b was compared with the analogous enzyme isolated from the Gram-negative bacterium Alcaligenes eutrophus H16. The hydrogenase of N. opaca 1b was purified by a new procedure applying chromatography on phenyl-Sepharose and DEAE-Sephacel with two columns in series. A homogeneous enzyme preparation with a specific activity of 74 mumol H2 oxidized.min-1.mg protein-1 and a yield of 32% was isolated. The A. eutrophus enzyme was purified as previously published. Both enzymes are tetrameric proteins composed of four non-identical subunits (alpha, beta, gamma, delta). The four subunits of both of these enzymes were separated and isolated as single polypeptides by preparative polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Immunological comparison of the four subunits of the Nocardia hydrogenase with those of the Alcaligenes enzyme showed that the alpha, beta, gamma, and delta subunits of one organism were serologically related to the analogous subunits of the other organism. Among themselves, the four subunits do not have any serological relationship. The eight individual polypeptides were also compared with respect to the NH2-terminal amino acid sequences determined by automated Edman degradation and to the amino acid compositions. Strong sequence similarities exist between the analogous subunits isolated from the two bacteria. Within the established N-terminal sequences the similarities between both alpha, beta, gamma and delta subunits amount to 63%, 79%, 80% and 65%, respectively. No similarities exist between the different, non-analogous subunits alpha, beta, gamma and delta.

Alcaligenes↗
PubMed1992

Derived amino acid sequences of the nosZ gene (respiratory N2O reductase) from Alcaligenes eutrophus, Pseudomonas aeruginosa and Pseudomonas stutzeri reveal potential copper-binding residues. Implications for the CuA site of N2O reductase and cytochrome-c oxidase.

The nosZ genes encoding the multicopper enzyme nitrous oxide reductase of Alcaligenes eutrophus H16 and the type strain of Pseudomonas aeruginosa were cloned and sequenced for structural comparison of their gene products with the homologous product of the nosZ gene from Pseudomonas stutzeri [Viebrock, A. & Zumft, W. G. (1988) J. Bacteriol. 170, 4658-4668] and the subunit II of cytochrome-c oxidase (COII). Both types of enzymes possess the CuA binding site. The nosZ genes were identified in cosmid libraries by hybridization with an internal 1.22-kb PstI fragment (NS220) of nosZ from P. stutzeri. The derived amino acid sequences indicate unprocessed gene products of 70084 Da (A. eutrophus) and 70695 Da (P. aeruginosa). The N-terminal sequences of the NosZ proteins have the characteristics of signal peptides for transport. A homologous domain, extending over at least 50 residues, is shared among the three derived NosZ sequences and the CuA binding region of 32 COII sequences. Only three out of nine cysteine residues of the NosZ protein (P. stutzeri) are invariant. Cys618 and Cys622 are assigned to a binuclear center, A, which is thought to represent the CuA site of NosZ and is located close to the C terminus. Two conserved histidines, one methionine, one aspartate, one valine and two aromatic residues are also part of the CuA consensus sequence, which is the domain homologous between the two enzymes. The CuA consensus sequence, however, lacks four strictly conserved residues present in all COII sequences. Cys165 is likely to be a ligand of a second binuclear center, Z, for which we assume mainly histidine coordination. Of 23 histidine residues in NosZ (P. stutzeri), 14 are invariant, 7 of which are in regions with a degree of conservation well above the 50% positional identity between the Alcaligenes and Pseudomonas sequences. Conserved tryptophan residues are located close to several potential copper ligands. Trp615 may contribute to the observed quenching of fluorescence when the CuA site is occupied.

Alcaligenes↗
PubMed1993

A comparison of NO and N2O production by the autotrophic nitrifier Nitrosomonas europaea and the heterotrophic nitrifier Alcaligenes faecalis.

Soil microorganisms are important sources of the nitrogen trace gases NO and N2O for the atmosphere. Present evidence suggests that autotrophic nitrifiers such as Nitrosomonas europaea are the primary producers of NO and N2O in aerobic soils, whereas denitrifiers such as Pseudomonas spp. or Alcaligenes spp. are responsible for most of the NO and N2O emissions from anaerobic soils. It has been shown that Alcaligenes faecalis, a bacterium common in both soil and water, is capable of concomitant heterotrophic nitrification and denitrification. This study was undertaken to determine whether heterotrophic nitrification might be as important a source of NO and N2O as autotrophic nitrification. We compared the responses of N. europaea and A. faecalis to changes in partial O2 pressure (pO2) and to the presence of typical nitrification inhibitors. Maximal production of NO and N2O occurred at low pO2 values in cultures of both N. europaea (pO2, 0.3 kPa) and A. faecalis (pO2, 2 to 4 kPa). With N. europaea most of the NH4+ oxidized was converted to NO2-, with NO and N2O accounting for 2.6 and 1% of the end product, respectively. With A. faecalis maximal production of NO occurred at a pO2 of 2 kPa, and maximal production of N2O occurred at a pO2 of 4 kPa. At these low pO2 values there was net nitrite consumption. Aerobically, A. faecalis produced approximately the same amount of NO but 10-fold more N2O per cell than N. europaea did. Typical nitrification inhibitors were far less effective for reducing emissions of NO and N2O by A. faecalis than for reducing emissions of NO and N2O by N. europaea.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1996

The Legionella pneumophila hel locus encodes intracellularly induced homologs of heavy-metal ion transporters of Alcaligenes spp.

We continued characterization of the Legionella pneumophila hel locus. Mutagenesis and DNA sequencing identified three genes similar to the czc and cnr loci of Alcaligenes eutrophus and the ncc locus of Alcaligenes xylosoxidans. On the basis of their similarity to these loci, we designated the L. pneumophila genes helC, helB, and helA. Mutations in the hel genes led to reduced cytopathicity towards U937 cells, although the mutant strains did not appear defective in other assays of virulence. Transcription of the hel locus was induced by the intracellular environment but was not induced by any of a variety of in vitro stress conditions. The function of the hel gene products remains to be determined.

Alcaligenes↗