Isolation of Pseudomonas pickettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols.

Three strains of Pseudomonas pickettii that can grow with 2,4,6-trichlorophenol (2,4,6-TCP) as the sole source of carbon and energy were isolated from different mixed cultures of soil bacterial populations that had been acclimatized to 2,4,6-TCP. These strains released 3 mol of chloride ion from 1 mol of 2,4,6-TCP during the complete degradation of the TCP. Of these strains, P. pickettii DTP0602 in high-cell-density suspension cultures dechlorinated various chlorophenols (CPs). Cells that were preincubated with 2,4,6-TCP converted isomers of 4-CP to the corresponding chloro-p-hydroquinones, but those preincubated with 4-CP converted CPs lacking a chlorine atom(s) at the o position to isomers of chlorocatechol. The ability of DTP0602 to dechlorinate 2,4,6-TCP was induced by 2,6-dichlorophenol, 2,3,6- and 2,4,6-TCP, and 2,3,4,6-tetrachlorophenol and was repressed in the presence of succinate or glucose.     

Cloning and characterization of the genes for p-nitrobenzoate degradation from Pseudomonas pickettii YH105.

Pseudomonas pickettii YH105 was isolated for its ability to utilize p-nitrobenzoate as the sole source of carbon, nitrogen, and energy. Degradation of p-nitrobenzoate by this strain proceeds through a reductive route as evidenced by the accumulation of ammonia in the culture medium during growth on p-nitrobenzoate. Enzyme assays and high-performance liquid chromatography (HPLC) analysis of culture supernatants indicate that p-nitrobenzoate is degraded through p-hydroxylaminobenzoate and protocatechuate. In order to clone the genes responsible for the initial steps in the catabolic pathway, a cosmid library was constructed with P. pickettii YH105 genomic DNA. The library was screened for clones capable of transforming p-nitrobenzoate to protocatechuate, using a plate assay specific for diphenolic compounds. HPLC analysis of culture supernatants confirmed that the cosmid clones did indeed produce protocatechuate from p-nitrobenzoate. Five positive cosmid clones that possessed this activity were identified. Restriction digests of the cosmid clones indicated that all of the clones had two EcoRI fragments in common (3.9 and 1.0 kb). One of these cosmid clones, designated pGJZ1601, was chosen for further analysis. Subcloning and activity assay experiments localized the genes responsible for the conversion of p-nitrobenzoate to protocatechuate to a 1.4-kb SalI-SphI DNA fragment. Further subcloning experiments localized the gene coding for p-nitrobenzoate reductase, responsible for the first enzymatic step in the catabolic pathway, to a 0.8-kb SalI-ApaI DNA fragment. The gene for the second step in the catabolic pathway, coding for hydroxylaminolyase, was located adjacent to the gene for the p-nitrobenzoate reductase.     

Isolation of Pseudomonas pickettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols.

Three strains of Pseudomonas pickettii that can grow with 2,4,6-trichlorophenol (2,4,6-TCP) as the sole source of carbon and energy were isolated from different mixed cultures of soil bacterial populations that had been acclimatized to 2,4,6-TCP. These strains released 3 mol of chloride ion from 1 mol of 2,4,6-TCP during the complete degradation of the TCP. Of these strains, P. pickettii DTP0602 in high-cell-density suspension cultures dechlorinated various chlorophenols (CPs). Cells that were preincubated with 2,4,6-TCP converted isomers of 4-CP to the corresponding chloro-p-hydroquinones, but those preincubated with 4-CP converted CPs lacking a chlorine atom(s) at the o position to isomers of chlorocatechol. The ability of DTP0602 to dechlorinate 2,4,6-TCP was induced by 2,6-dichlorophenol, 2,3,6- and 2,4,6-TCP, and 2,3,4,6-tetrachlorophenol and was repressed in the presence of succinate or glucose.     

Illness associated with contamination of drinking water supplies with phenol.

In January 1984 the River Dee in north Wales was contaminated with phenol, with subsequent contamination of the tap water received by about two million consumers. A retrospective postal survey of 594 households was undertaken to determine whether consumption of this contaminated water was associated with illness. Subjects in areas that received contaminated water reported significantly more gastrointestinal illness than those in a nearby unexposed area (32.6% v 8.7%, p less than 0.00001) as well as reporting a higher incidence of any symptoms (43.6% v 18.4%, p less than 0.00001). Symptoms were consistent with phenol poisoning and bore a strong temporal relation to the pollution of the supply, but they developed at concentrations of phenols previously considered to be safe by the water authorities concerned. Chlorophenols produced during the treatment of water may have aggravated the problem.     

A taxonomic study of clinical isolates of Pseudomonas pickettii, 'P. thomasii' and 'group IVd' bacteria

On the basis of cluster analysis, average similarities within and between groups, and DNA base composition of selected strains, Pseudomonas pickettii appeared to be a distinct species comprising several biotypes. Although some or all of these biotypes, represented by subclusters in our computer study, may ultimately warrant recognition as separate species, our results were not conclusive enough to warrant such a proposal at present. Most strains tentatively named 'P. thomasii' could be included in P. pickettii so that the name P. pickettii, which was validly published whilst 'P. thomasii' was not, takes priority over 'P. thomasii'. Strains of Group Va (Tatum et al., 1974) examined were also included in P. pickettii. Group IVd (King, 1964) did not appear to be a natural group but some of the strains could also be included in P. pickettii.     

Carbon monoxide-insensitive respiratory chain of Pseudomonas carboxydovorans.

Experiments employing electron transport inhibitors, room- and low-temperature spectroscopy, and photochemical action spectra have led to a model for the respiratory chain of Pseudomonas carboxydovorans. The chain is branched at the level of b-type cytochromes or ubiquinone. One branch (heterotrophic branch) contained cytochromes b558, c, and a1; the second branch (autotrophic branch) allowed growth in the presence of CO and contained cytochromes b561 and o (b563). Electrons from the oxidation of organic substrates were predominantly channelled into the heterotrophic branch, whereas electrons derived from the oxidation of CO or H2 could use both branches. Tetramethyl-p-phenylenediamine was oxidized via cytochromes c and a exclusively. The heterotrophic branch was sensitive to antimycin A, CO, and micromolar concentrations of cyanide. The autotrophic branch was sensitive to 2-n-heptyl-4-hydroxyquinoline-N-oxide, insensitive to CO, and inhibited only by millimolar concentrations of cyanide. The functioning of cytochrome a1 as a terminal oxidase was established by photochemical action spectra. Reoxidation experiments established the functioning of cytochrome o as an alternative CO-insensitive terminal oxidase of the autotrophic branch.     

Bacteria associated with the sponge Spongia officinalis as indicators of contamination

A lot of micro-organisms can been found in the sponge body. In the present study, bacteria and fungi were isolated from the massive commercial sponge Spongia officinalis Linnaeus, 1759 (Porifera, Demospongiae). Samples (sponge extract and sea water) were collected from several areas of the Aegean Sea (ports, beaches, eutrophic gulf and open sea) with different levels and types of contamination. Bacteria identified in sponge extract belong to the genera Escherichia, Morganella, Proteus, Pasteurella, Aeromonas, Pseudomonas and Acinetobacter. Two fungal genera, Trichosporum and Fisarium, were identified in sponge extract. Bacterial load was greater in sponge extract than in proximal sea water, reflecting the sponge ability to concentrate bacteria in its body. The assessment of bacteria associated with the sponge S. officinalis as indicators of contamination is proposed.     

Pseudomonas streptomycin resistance transposon associated with R-plasmid mobilization.

Plasmid pMG1 encodes resistance to gentamicin, streptomycin, sulfonamides, and mercuric ions and also mobilizes pRO161, a transfer-deficient plasmid derived from RP1. Upon mobilization, pRO161 acquires streptomycin resistance (Smr) and can subsequently be remobilized by pMG1 at significantly higher frequencies than pRO161 itself. Both the initial acquisition of Smr and the subsequent mobilization of the transfer-deficient plasmid are recA independent: thus, the Smr determinant appears to be located on a transposon, disignated Tn904. Tn904 transposes to a variety of other plasmids, including RP1, FP2, R388, K, pRO1600, and pBR322, and in some cases the acquisition of this transposon accompanied deletions in the target plasmid. When no deletion occurred, target plasmids gained 5.2 kilobase pairs of DNA and new restriction endonuclease cleavage sites for AvaI, BglII, PstI, SmaI, and SstI. Physical analysis of such plasmids showed that the Tn904 termini are inverted repeat DNA sequences of approximately 124 base pairs. After cloning into vector pRO1723, a single site for restriction endonuclease AvaI was identified within the Smr determinant of Tn904. In Escherichia coli, but not in Pseudomonas aeruginosa. Tn904 shows a gene dosage-dependent expression of streptomycin resistance.     

Pseudomonas aeruginosa infections associated with use of contaminated medicaments.

Pseudomonas aeruginosa was recovered from three hospital-prepared medicaments being used on the wards. Sixty-six patients were studied to observe the effect of using these contaminated medicaments. Psaeruginosa was recovered from 29 patients; in five the strains recovered bore a close resemblance to strains previously isolated from the contaminated medicaments.     

Attenuation of DNA-protein interactions associated with intrinsic, sequence-dependent DNA curvature.

Inherently curved DNA segments, associated with short runs of adenines, have been identified in many gene regulatory regions, yet their physiological significance remains unknown. The observations reported in this study indicate that intrinsically bent nucleic acid fragments are characterized by substantially attenuated affinities toward DNA-binding proteins involved in structural functions, such as H1 histone and protamine, as well as toward various DNA-modifying enzymes including ligases and exo- and endonucleases. Two mechanisms might be responsible for the altered binding properties. According to the first mechanism, the attenuated binding affinities and the bending represent two independent consequences of the unique structural parameters exhibited by A-tracts. Indeed, analysis of the degradation products obtained upon exposure of the curved sequences to various chemical nucleases points toward the narrowing of the DNA minor groove, a conformational modulation known to characterize A-tracts and to run along the axially-bent motifs, as a potential determinant of the observed binding attenuation. Alternatively, the conformational constraints which result from the stable bending might act to modulate the strength of DNA-protein interactions. Although the factor directly responsible for the altered binding affinities revealed by the bent sequences cannot as yet be conclusively resolved, it is proposed that a reiteration of this specific factor, being either an A-tract or a bend, in phase with the DNA helical repeat acts to amplify the modulation of the binding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors associated with immediate abortion complications.

OBJECTIVE: To identify factors associated with increased risk of immediate complications from induced abortion. DESIGN: Retrospective analysis of a provincial database. SETTING: All Ontario general hospitals in which abortions are performed and all free-standing abortion clinics in Ontario. POPULATION: Women in Ontario aged 15 to 44 years who underwent an induced abortion in the province (without concurrent sterilization) between Jan. 1, 1992, and Dec. 31, 1993. OUTCOME MEASURES: Recording of complications at the time of the procedure, gestational age, type of procedure, place of abortion (hospital or clinic), and patient''s age, parity and history of previous abortion (spontaneous or induced). RESULTS: During the study period 83 469 abortions were performed that met our inclusion criteria. Immediate complications were reported in 571 cases (0.7%). Multivariate logistic regression analysis revealed that, after other variables were controlled for, the patient''s age, parity and history of previous abortions (spontaneous or induced) were not significant risk factors for immediate complications; however, gestational age, method of abortion and place of abortion were significant risk factors (p < 0.001). The odds ratio (OR) for having a complication from abortion was 1.3 (95% confidence interval [CI] 1.02 to 1.63) between 9 and 12 weeks, compared with having one after abortion at 9 weeks or earlier, and increased to 3.3 (95% CI 2.23 to 5.00) after abortion between 17 and 20 weeks. Compared with surgical dilatation and curettage (D&C), instillation of saline and instillation of prostaglandins were more likely to be associated with immediate complications (OR 24.0, 95% CI 13.22 to 43.70, and OR 11.7, 95% CI 6.43 to 21.18, respectively), whereas both suction D&C and insertion of a laminaria tent were less likely to be associated with immediate complications (OR 0.4, 95% CI 0.26 to 0.67, and OR 0.3, 95% CI 0.19 to 0.52, respectively). Compared with women who had an abortion in a free-standing clinic, the risk for immediate complications was greater among those who had an abortion in a hospital, especially a teaching hospital (OR 1.9, 95% CI 1.38 to 2.58), a nonteaching hospital with 200 to 399 acute care beds (OR 3.1, 95% CI 2.27 to 4.21) and a nonteaching hospital with fewer than 200 acute care beds (OR 5.9, 95% CI 4.04 to 8.64). CONCLUSION: The risk of immediate complications from induced abortion is very low. Unlike in previous studies, the woman''s age, parity and history of previous spontaneous or induced abortions were not found to be risk factors. However, advancing gestational age and procedures involving instillation of saline or prostaglandins were predictive factors of immediate complications.     

Membrane-bound respiratory chain of Pseudomonas aeruginosa grown aerobically.

The electron transport chain of the gram-negative bacterium Pseudomonas aeruginosa, grown aerobically, contained a number of primary dehydrogenases and respiratory components (soluble flavin, bound flavin, coenzyme Q9, heme b, heme c, and cytochrome o) in membrane particles of the organism. Cytochrome o, about 50% of the b-type cytochrome, seemed to function as a terminal oxidase in the respiratory chain. The electron transport chain of P. aeruginosa grown aerobically was suggested to be lined up in order of primary dehydrogenase, b, c1, c, o, and oxygen.     

Factors associated with outcome of renal transplantation.

To explore the associations between a number of preoperative risk factors and the failure of renal grafts 99 consecutive patients were followed for up to 7 years after transplantation. The patients had all received their grafts from nonliving donors; the operations were performed at one hospital. Statistical analysis in relation to several outcomes showed that rapidly progressive glomerulonephritis, pre-existing cardiovascular disease, the degree of presensitization to histocompatibility antigens and the donor''s being of blood group B were associated with an increased risk of graft rejection or death after transplantation. The risks of acute and accelerated rejection were associated with different factors, which suggests that distinct pathogenetic processes may be involved. The risk of technical failure was associated with immunologic factors, which suggests the possibility that this outcome was not caused by surgical difficulties alone.     

Factors contributing to the survival of a strain of Pseudomonas cepacia in chlorhexidine solutions

Adsorption of Pseudomonas cepacia onto the surface of glass containers enables cells to survive in the presence of user strength chlorhexidine (0.05% w/v). The organisms were found to be firmly attached to the glass and colonised glass slides could be used to infect uncontaminated chlorhexidine solutions. The efficacy of chlorhexidine against Ps. cepacia decreased with decreasing pH. Storing infected solutions at low temperatures reduced the toxicity of chlorhexidine and promoted longer survival.