Identification and distribution of Pseudomonas stutzeri in clinical material

During the 19 year period ending December 1984, 114 (2.4%) of 4840 strains of Gram-negative non-fermentative bacteria submitted, mainly by laboratories in the UK, to the National Collection of Type Cultures for computer-assisted identification were strains of Pseudomonas stutzeri. These figures suggest that Ps. stutzeri is a relatively uncommon species in clinical material in the UK but that when it does occur laboratories have difficulty in identifying it. The sources from which the strains were isolated and also characteristics of the species by which it may be recognized are reported. The clinical significance of Ps. stutzeri is discussed and also the susceptibility of this species to antimicrobial agents.     

Identification of siderophores of Pseudomonas stutzeri

We have identified two types of siderophores produced by Pseudomonas, one of which has never before been found in the genus. Twelve strains of Pseudomonas stutzeri belonging to genomovars 1, 2, 3, 4, 5, and 9 produced proferrioxamines, the hydroxamate-type siderophores. Pseudomonas stutzeri JM 300 (genomovar 7) and DSM 50238 (genomovar 8) and Pseudomonas balearica DSM 6082 produced amonabactins, catecholate-type siderophores. The major proferrioxamines detected were the cyclic proferrioxamines E and D2. Pseudomonas stutzeri KC also produced cyclic (X1 and X2) and linear (G1 and G2a-c) proferrioxamines. Our data indicate that the catecholate-type siderophores belong to amonabactins P 750, P 693, T 789, and T 732. A mutant of P. stutzeri KC (strain CTN1) that no longer produced the secondary siderophore pyridine-2,6-dithiocarboxylic acid continued to produce all other siderophores in its normal spectrum. Siderophore profiles suggest that strain KC (genomovar 9) belongs to the proferrioxamine-producing P. stuzeri. Moreover, a putative ferrioxamine outer membrane receptor gene foxA was identified in strain KC, and colony hybridization showed the presence of homologous receptor genes in all P. stutzeri and P. balearica strains tested.     

Identification and distribution of Flavobacterium meningosepticum in clinical material

During the 19 year period ending December 1984, 82 (1.7%) of 4840 strains of Gram-negative non-fermentative bacteria submitted to the National Collection of Type Cultures (NCTC) for computer-assisted identification were Flavobacterium meningosepticum. These figures suggest either that F. meningosepticum occurs only rarely in clinical material in the UK, or that when it does occur it is not always recognized. The sources from which the NCTC strains were isolated are reported and also the characteristics by which the species may be identified. The clinical significance of F. meningosepticum is reviewed, particularly its role in neonatal meningitis, of which there have been but two reported cases in the UK, both imported. The susceptibility of the species to antimicrobial agents is discussed and also antimicrobial therapy of neonatal meningitis due to this species.     

Identification and distribution of Flavobacterium meningosepticum in clinical material

During the 19 year period ending December 1984, 82 (1.7%) of 4840 strains of Gram-negative non-fermentative bacteria submitted to the National Collection of Type Cultures (NCTC) for computer-assisted identification were Flavobacterium meningosepticum. These figures suggest either that F. meningosepticum occurs only rarely in clinical material in the UK, or that when it does occur it is not always recognized. The sources from which the NCTC strains were isolated are reported and also the characteristics by which the species may be identified. The clinical significance of F. meningosepticum is reviewed, particularly its role in neonatal meningitis, of which there have been but two reported cases in the UK, both imported. The susceptibility of the species to antimicrobial agents is discussed and also antimicrobial therapy of neonatal meningitis due to this species.     

Biology of Pseudomonas stutzeri

Pseudomonas stutzeri is a nonfluorescent denitrifying bacterium widely distributed in the environment, and it has also been isolated as an opportunistic pathogen from humans. Over the past 15 years, much progress has been made in elucidating the taxonomy of this diverse taxonomical group, demonstrating the clonality of its populations. The species has received much attention because of its particular metabolic properties: it has been proposed as a model organism for denitrification studies; many strains have natural transformation properties, making it relevant for study of the transfer of genes in the environment; several strains are able to fix dinitrogen; and others participate in the degradation of pollutants or interact with toxic metals. This review considers the history of the discovery, nomenclatural changes, and early studies, together with the relevant biological and ecological properties, of P. stutzeri.     

Silver resistance in Pseudomonas stutzeri

Silver resistance was studied in a silver-resistant Pseudomonas stutzeri AG259 strain and compared to a silver-sensitive P. stutzeri JM303 strain. Silver resistance was not due to silver complexation to intracellular polyphosphate or the presence of low molecular weight metal-binding protein(s). Both the silver-resistant and silver-sensitive P. stutzeri strains produced H₂S, with the silver-resistant AG259 strain producing lower amounts of H₂S than the silver-sensitive JM303 strain. However, intracellular acid-labile sulfide levels were generally higher in the silver-resistant P. stutzeri AG259 strain. Silver resistance may be due to formation of silver-sulfide complexes in the silver-resistant P. stutzeri AG259 strain.     

Nitrogen fixation in Pseudomonas stutzeri

A recently developed oxygen gradient system and a complex medium were used to isolate a microaerobically N₂-fixing heterotrophic bacterium from the rhizosphere of a high fixing Sorghum nutans cultivar. The isolate was identified as nif(+) phenotype of Pseudomonas stutzeri on the basis of cultural, physiological and biochemical characteristics, including DNA/DNA hybridization. N₂ fixation was demonstrated by assimilation of ¹⁵N₂ into cellular protein; the physiology of nitrogen fixation was studied. The isolate contains one 30 MD plasmid and can be cured with associated loss of N₂ fixation capability.Dedicated to Prof. Dr. W. Nultsch on the occasion of his 60th birthday     

Biology of Pseudomonas stutzeri.

Pseudomonas stutzeri is a nonfluorescent denitrifying bacterium widely distributed in the environment, and it has also been isolated as an opportunistic pathogen from humans. Over the past 15 years, much progress has been made in elucidating the taxonomy of this diverse taxonomical group, demonstrating the clonality of its populations. The species has received much attention because of its particular metabolic properties: it has been proposed as a model organism for denitrification studies; many strains have natural transformation properties, making it relevant for study of the transfer of genes in the environment; several strains are able to fix dinitrogen; and others participate in the degradation of pollutants or interact with toxic metals. This review considers the history of the discovery, nomenclatural changes, and early studies, together with the relevant biological and ecological properties, of P. stutzeri.     

Silver accumulation and resistance in Pseudomonas stutzeri

Silver (Ag) resistance and accumulation were investigated in Ag-resistant Pseudomonas stutzeri strain AG259 and Ag-sensitive P. stutzeri strain JM303. Both strains exhibited a similar pattern of silver accumulation although to different final concentrations. Energy-dispersive X-ray analyses revealed the association of dense silver deposits with the Ag-resistant strain, but not the Ag-sensitive strain. Toluene permeabilization or incubation of cells at 2°C resulted in decreased Ag accumulation in both strains. This suggests that Ag accumulation may be energy dependent. A decrease in Ag accumulation was observed when cells were pretreated with 2,4-dinitrophenol (2,4-DNP). No decrease was observed using carbonyl cyanide m-chlorphenyl-hydrazone (CCCP). However, it was observed that both 2,4-DNP and CCCP complexed to Ag, making interpretation of accumulation results difficult. Washing of cells incubated in the presence of Ag with ethylenediaminetetraacetic acid (EDTA) or hydrochloric acid did not result in decreased Ag accumulation.     

Pleuropneumonia caused by Pseudomonas stutzeri

Biological characteristics and antibiotic sensitivity of P. stutzeri strain, isolated from a child with pleuropneumonia, are presented. Formation of rugous colonies, growth at 41 degrees C and in the presence of 6.5% of NaCl, the positive results of the oxidase and nitrate reductase tests, the negative signs of arginine hydrolase and lysine decarboxylase activity permit the identification of this Pseudomonas species. The isolated culture has proved to be sensitive to amino glycoside antibiotics, carbonicillin and polymyxin.     

Pyrimidine biosynthesis in Pseudomonas stutzeri ATCC 17588

The de novo pyrimidine biosynthetic enzymes in the denitrifying bacterium Pseudomonas stutzeri ATCC 17588 were assayed and their activities were lower in glucose-grown cells than in succinate-grown cells. When P. stutzeri was grown in the presence of uracil, the de novo enzyme activities in succinate-grown cells were lowered while they remained largely unchanged in glucose-grown cells. A uracil auxotroph of P. stutzeri, deficient for aspartate transcarbamoylase activity, was isolated and its auxotrophic requirement was met by only uracil and cytosine. The inability of pyrimidine ribonucleosides to meet the auxotrophic requirement was related to the limited ability of P. stutzeri to transport uridine and cytidine. Pyrimidine limitation of the auxotroph elevated the de novo enzyme activities indicating that this pathway may be repressible by a uracil-related compound in succinate-grown P. stutzeri cells. Regulation of pyrimidine synthesis in P. stutzeri was similar to that observed for other pseudomonads classified within rRNA homology group I.     

Characterization of dihydropyrimidinase from Pseudomonas stutzeri

Dihydropyrimidinase from Pseudomonas stutzeri ATCC 17588 was purified 100-fold and characterized. It was found that dihydrouracil, dihydrothymine and hydantoin could serve as substrates for the partially purified enzyme. The K _m values for dihydrouracil, dihydrothymine and hydantoin were determined to be 19.6 M, 21.3 M and 36.4 M, respectively, while their respective V _max values were 0.836 mol/min, 0.666 mol/min and 2.21 mol/min. Between pH 7.5 and 9.0, enzyme activity was shown to be maximal. The optimum temperature for enzyme activity was 45 °C. Using gel filtration, the molecular weight of the enzyme was calculated to be approximately 115000 Da. Metal ions were found to influence the level of enzyme activity. Dihydropyrimidinase activity was stimulated by magnesium ions and inhibited by either zinc or copper ions.     

Comparative responses of Pseudomonas stutzeri and Pseudomonas aeruginosa to antibacterial agents

The sensitivity of six strains of Pseudomonas stutzeri (NCIMB 568, 10783, 11358, 11359, JM 302, JM 375) to cationic antiseptics, mercury compounds, the parabens, phenolics, EDTA and various antibiotics was compared with Pseudomonas aeruginosa NCIMB 8626. All Ps. stutzeri strains were highly sensitive to chlorhexidine diacetate, organomercurials and triclosan, but rather less so to quarternary ammonium compounds (QACs). They were also sensitive to other biocidal agents and more sensitive to many antibiotics than the strain of Ps. aeruginosa. There was little correlation between uptake of chlorhexidine diacetate or cetylpyridinium chloride by dense suspensions of organisms, leakage of intracellular constituents and loss of cell viability.     

Biochemical and chemotaxonomic characterization of Pseudomonas stutzeri genomovars

A total of 48 strains representing the seven Pseudomonas stutzeri genomovars (DNA/DNA homology groups) were studied for cellular fatty acid composition, physiological characteristics and protein profiles. All strains were found to be homogeneous with respect to their fatty acid patterns. Numerical analysis of physiological properties demonstrated a considerable phenotypic heterogeneity within the genomovars. Characterization of the individual genomic groups on the basis of biochemical tests was not possible. In a numerical study of cellular protein patterns, two main clusters were obtained, one representing genomovars 1, 6 and 7 characterized by a high G + C content (mean value > 64 mol%), the other representing genomovars 2, 3, 4 and 5 with a low G + G content (< 64 mol%). The standardized cellular protein patterns have potential for differentiation of the genomic groupings within the species Ps. stutzeri as currently circumscribed.     

Pseudomonas stutzeri and related species undergo natural transformation

Cells of Pseudomonas stutzeri are naturally transformed by homologous chromosomal DNA; they do not require chemical treatment to become competent. This capacity to undergo natural transformation was found to be shared by the closely related species P. mendocina, P. alcaligenes, and P. pseudoalcaligenes, but was not detectable in strains of P. aeruginosa, P. perfectomarinus, P. putida, P. fluorescens, or P. syringae. P. stutzeri could be transformed either on plates or in liquid medium. Only double-stranded chromosomal DNA was effective; single-stranded DNA and plasmid DNA were not. DNA fragments larger than 10 kilobase pairs were more effective than smaller fragments. The transformation frequency was proportional to DNA concentration from 1 ng/ml to 1 microgram/ml; higher concentrations were saturating. The maximum frequency, about 10(-4) transformants per recipient cell, was obtained with cells from a culture in the early stationary growth phase. A variety of chromosomal mutations have been transformed, including mutations to auxotrophy and to antibiotic resistance. Other systems for genetic exchange in P. stutzeri have not yet been found; transformation offers a means for the genetic analysis of this metabolically versatile organism.     

Identification and DNA sequencing of a new plasmid (pPST1) in Pseudomonas stutzeri MO-19

A cryptic plasmid, pPST1, was isolated from Pseudomonas stutzeri MO-19 and its complete nucleotide sequence was determined. This plasmid consisted of 1446 bp and could encode a putative polypeptide of 152 amino acid residues (ORF1) in an open reading frame. The putative protein contained a sequence homologous to the sequences found in DNA-binding sites.     

Stability of immobilized maltotetraose-forming amylase from Pseudomonas stutzeri

The stability of immobilized maltotetraose (G(4))-forming amylase (1,4-alpha-D-glucan maltoteraohydrolase, EC 3.2.1.60) from Pseudomonas stutzeri was investigated in both batch and continous processes. The inactivation process of the immobilized enzyme seemed to obey first-order kinetics, and the immobilized enzyme became more stable when coexisting with 20-30 wt % substrate and calcium ions. From intensive studies on the operational stability in the continuous process, the apparent half-life of G(4) productivity in a constant-flow system was mainly affected by the reaction temperature, substrate concentration, and initial immobilized enzyme activity. A new factor, immobilized enzyme stability factor f(s), was proposed to evaluate the half-life of the immobilized enzyme system.