共查询到20条相似文献,搜索用时 15 毫秒
1.
A bacterial strain identified as Pseudomonas aeruginosa was isolated from a soil consortium able to mineralize pentane. P. aeruginosa could metabolize methyl t-butyl ether (MTBE) in the presence of pentane as the sole carbon and energy source. The carbon balance for this strain, grown
on pentane, was established in order to determine the fate of pentane and the growth yield (0.9 g biomass/g pentane). An inhibition
model for P. aeruginosa grown on pentane was proposed. Pentane had an inhibitory effect on growth of P. aeruginosa, even at a concentration as low as 85 μg/l. This resulted in the calculation of the following kinetic parameters (μ max = 0.19 h −1, K
s = 2.9 μg/l, K
i = 3.5 mg/l). Finally a simple model of MTBE degradation was derived in order to predict the quantity of MTBE able to be degraded
in batch culture in the presence of pentane. This model depends only on two parameters: the concentrations of pentane and
MTBE.
Received: 16 July 1998 / Received revision: 11 November 1998 / Accepted 31 November 1998 相似文献
2.
The catabolism of eugenol in Pseudomonas sp. strain HR199 (DSM7063) proceeds via coniferyl alcohol, coniferyl aldehyde, ferulic acid, vanillin, vanillate and protocatechuate,
which is further degraded by the ortho-cleavage pathway. The vanillin dehydrogenase of Pseudomonas sp. strain HR199, which catalyses the NAD +-dependent oxidation of vanillin to vanillate, was inactivated by the insertion of omega elements into the vdh gene, which was characterized recently. Omega elements conferring resistance against kanamycin (ΩKm) or gentamycin (ΩGm)
were constructed by polymerase chain reaction amplification of the aminoglycoside 3′- O-phosphotransferase gene and the gentamycin- 3-acetyltransferase gene, using the plasmids pSUP5011 and pBBR1MCS-5 respectively
as template DNA. A 211-bp BssHII fragment of the vdh gene was substituted by ΩKm or ΩGm, and the functional vdh gene was replaced by vdhΩKm or vdhΩGm in Pseudomonas sp. strain HR199 by homologous recombination. Cells of the mutant Pseudomonas sp. strain HR vdhΩKm, pregrown on gluconate, accumulated up to 2.9 mM vanillin during incubation in mineral medium with 6.5 mM eugenol. As
a result of another vanillin dehydrogenase activity (VDH-II), the accumulated vanillin was further degraded, when coniferyl
aldehyde was exhausted from the medium. Characterization of the purified VDH-II revealed the identity of this enzyme with
the recently characterized coniferyl-aldehyde dehydrogenase.
Received: 19 March 1999 / Received revision: 31 June 1999 / Accepted: 5 July 1999 相似文献
3.
Pseudomonas aeruginosa outer membrane protein F was purified by extraction from polyacrylamide gels of cell envelope proteins of an Escherichia coli strain expressing the cloned gene for protein F. Antisera directed against protein F purified from P. aeruginosa PAO1 reacted with this E. coli strain by immunofluorescence assay and immunoblotting, whereas these antisera were nonreactive with E. coli strains lacking the Pseudomonas protein F gene. The protein F purified from this E. coli strain was used to immunize mice by intramuscular injection of 10 µg of protein F preparation on days 1 and 14, followed by burn and challenge of the mice on day 28. As compared with control mice immunized with E. coli K-12 lipopolysaccharide, immunization with the E. coli-derived protein F afforded significant protection against subsequent challenge with heterologous Fisher-Devlin immunotype 5 and 6 strains of P. aeruginosa. Antisera from mice immunized with the E. coli-derived protein F reacted at bands corresponding to protein F and 2-mercaptoethanol-modified protein F upon immunoblotting against cell envelope proteins of the PAO1, immunotype 5, and immunotype 6 strains of P. aeruginosa and the E. coli strain containing the cloned F gene, but failed to react at these sites in an E. coli strain lacking the F gene. These data demonstrate that P. aeruginosa protein F produced in E. coli through genetic engineering techniques retains its vaccine efficacy in the complete absence of any P. aeruginosa lipopolysaccharide. 相似文献
4.
A novel method for the determination of microbial growth kinetics on hydrophobic volatile organic compounds (VOC) has been
developed. A stirred tank reactor was operated as a fed-batch system to which the VOC was continuously fed via the gas phase,
assuring a constant VOC concentration in the mineral medium. A flow of air was saturated with the VOC, and then mixed with
a further flow of air, to obtain a predetermined VOC concentration. Thus, different VOC concentrations in the mineral medium
could be obtained by altering the VOC concentration in the feed gas. The growth kinetics of Xanthobacter autotrophicus GJ10 on 1,2-dichloroethane (DCE) and of Pseudomonas sp. strain JS150 on MonoChloroBenzene (MCB) were assessed using this method. The growth of strain JS150 was strongly inhibited
at MCB concentrations higher than 160 mg l −1, and the results were fitted using a piecewise function. The growth kinetics of strain GJ10 were described by the Luong model
where maximum growth rate μ max = 0.12 h −1, substrate saturation constant K
S = 7.8 mg l −1, and maximum substrate concentration S
m (above which growth is completely inhibited) = 1080 mg l −1. Varying nitrogen and oxygen flows enabled the effect of oxygen concentration on the growth kinetics of Pseudomonas JS150 to be determined.
Received: 30 November 1998 / Received revision: 19 March 1999 / Accepted: 20 March 1999 相似文献
5.
Comamonas testosteroni strain R5 is a phenol-degrading bacterium which expresses a phenol-oxygenating activity that is characterized by low K
s (the apparent half-saturation constant in Haldane's equation) and low K
SI (the apparent inhibition constant) values. We have now cloned the gene cluster encoding a phenol hydroxylase ( phcKLMNOP) and its cognate regulator ( phcR) from strain R5. Transformation of Pseudomonas aeruginosa PAO1c (Phenol − Catechol +) with pROR502, a derivative of pRO1614 containing the cloned genes, confers the ability to grow on phenol as the sole carbon
source. The K
s and K
SI values for the phenol-oxygenating activity of PAO1c(pROR502) are almost identical to those of strain R5, suggesting that
the phcKLMNOP genes encode the major phenol hydroxylase in strain R5. A phylogenetic analysis shows the phenol hydroxylase from strain
R5 to be more closely related to toluene/benzene-2-monooxygenase (Tb2m) from Pseudomonas sp. JS150 than to the phenol hydroxylases from P. putida CF600 and BH, or to the phenol hydroxylase from Ralstonia eutropha E2. Analysis of the substrate specificity of PAO1c(pROR502) and PAO1c derivatives expressing phenol hydroxylase from P. putida BH or from R. eutropha E2 indicates that these phenol hydroxylases catalyze the oxidation not only of phenol and cresols but also of toluene and
benzene.
Received: 29 March 1999 / Accepted: 18 July 1999 相似文献
6.
A Pichia pastoris strain with stereoselective nitrile hydratase activity has been constructed by engineering the co-expression of three genes
derived from Pseudomonas putida. Using a technique that could be widely applicable, the genes encoding nitrile hydratase α and β structural subunits and
P14K accessory protein were first assembled as individual expression cassettes and then incorporated onto one plasmid, which
was integrated into the P. pastoris chromosome. The resulting strain can be used as a catalyst for bioconversions requiring stereospecific nitrile hydrolysis.
Received: 3 November 1998 / Received revision: 25 February1999 / Accepted: 14 March 1999 相似文献
7.
Pseudomonas sp. 61-3 accumulated a blend of poly(3-hydroxybutyrate) [P(3HB)] homopolymer and a random copolymer consisting of 3-hydroxyalkanoate
(3HA) units of 4–12 carbon atoms. The genes encoding β-ketothiolase (PhbA Re) and NADPH-dependent acetoacetyl-CoA reductase (PhbB Re) from Ralstoniaeutropha were expressed under the control of promoters for Pseudomonas sp. 61-3 pha locus or R. eutropha phb operon together with phaC1
Ps gene (PHA synthase 1 gene) from Pseudomonas sp. 61-3 in PHA-negative mutants P. putida GPp104 and R. eutropha PHB −4 to produce copolyesters [P(3HB- co-3HA)] consisting of 3HB and medium-chain-length 3HA units of 6–12 carbon atoms. The introduction of the three genes into
GPp104 strain conferred the ability to synthesize P(3HB- co-3HA) with relatively high 3HB compositions (up to 49 mol%) from gluconate and alkanoates, although 3HB units were not incorporated
at all or at a very low fraction (3 mol%) into copolyesters by the strain carrying phaC1
Ps gene only. In addition, recombinant strains of R. eutropha PHB −4 produced P(3HB- co-3HA) with higher 3HB fractions from alkanoates and plant oils than those from recombinant GPp104 strains. One of the recombinant
strains, R. eutropha PHB −4/pJKSc46- pha, in which all the genes introduced were expressed under the control of the native promoter for Pseudomonas sp. 61-3 pha locus, accumulated P(3HB- co-3HA) copolyester with a very high 3HB fraction (85 mol%) from palm oil. The nuclear magnetic resonance analyses showed that
the copolyesters obtained here were random copolymers of 3HB and 3HA units.
Received: 12 July 1999 / Received revision: 1 October 1999 / Accepted: 2 October 1999 相似文献
8.
Bioaugmentation has previously been unreliable for the in situ clean-up of contaminated soils because of problems with poor
survival and the rapid decline in activity of the bacterial inoculum. In an attempt to solve these problems, a 500-l batch
fermenter was investigated for its ability to deliver inoculum repeatedly to contaminated soils via irrigation lines. In a
field experiment, mesocosms were filled with 350 kg soil containing 100 mg kg −1 atrazine, and inoculated one, four or eight times with an atrazine-degrading bacterial consortium that was produced in the
fermenter. After 12 weeks, no significant degradation of atrazine had occurred in soil that was inoculated only once; whereas,
mesocosms inoculated four and eight times mineralized 38% and 72% of the atrazine respectively. Similar results were obtained
in a laboratory experiment using soil contaminated with 100 mg kg −1 [ 14C]atrazine. After 35 days, soil that was inoculated once with 10 8 cfu ml −1 of the consortium or with the atrazine-degrading bacterium, Pseudomonas sp. strain ADP, mineralized 17% and 35% of the atrazine respectively. In comparison, microcosms inoculated every 3 days with
the consortium or with Pseudomonas sp. (ADP) mineralized 64% or 90% of the atrazine over this same period. Results of these experiments suggest that repeated
inoculation from an automated fermenter may provide a strategy for bioaugmentation of contaminated soil with xenobiotic-degrading
bacteria.
Received: 20 November 1998 / Received revision: 8 February 1999 / Accepted: 12 February 1999 相似文献
9.
Pseudomonas aeruginosa depends on its quorum sensing (QS) system for its virulence factors’ production and biofilm formation. Biofilms of P. aeruginosa on the surface of indwelling catheters are often resistant to antibiotic therapy. Alternative approaches that employ QS inhibitors alone or in combination with antibiotics are being developed to tackle P. aeruginosa infections. Here, we have studied the mechanism of action of 3-Phenyllactic acid (PLA), a QS inhibitory compound produced by Lactobacillus species, against P. aeruginosa PAO1. Our study revealed that PLA inhibited the expression of virulence factors such as pyocyanin, protease, and rhamnolipids that are involved in the biofilm formation of P. aeruginosa PAO1. Swarming motility, another important criterion for biofilm formation of P. aeruginosa PAO1, was also inhibited by PLA. Gene expression, mass spectrometric, functional complementation assays, and in silico data indicated that the quorum quenching and biofilm inhibitory activities of PLA are attributed to its ability to interact with P. aeruginosa QS receptors. PLA antagonistically binds to QS receptors RhlR and PqsR with a higher affinity than its cognate ligands N-butyryl-l-homoserine lactone (C4–HSL) and 2-heptyl-3,4-dihydroxyquinoline (PQS; Pseudomonas quinolone signal). Using an in vivo intraperitoneal catheter-associated medaka fish infection model, we proved that PLA inhibited the initial attachment of P. aeruginosa PAO1 on implanted catheter tubes. Our in vitro and in vivo results revealed the potential of PLA as anti-biofilm compound against P. aeruginosa. 相似文献
10.
Pseudomonas sp. D7-4 and Pseudomonas sp. B13 FR1(pFRC20P) degraded mixtures of chloro- and methyl-substituted benzoates exclusively via an extended ortho pathway, whereas in Pseudomonas putida WR201 both ortho and meta fission were induced by mixtures of 3-chloro- and 3-methylbenzoate or even by 3-chlorobenzoate alone. The competition behaviour
of these strains was compared in batch and in chemostat cultures. Despite misrouting of metabolites, strain WR201 was competitive,
in a lot of the competition experiments, with mixtures of these substrates. Only in a narrow range of the mixing ratio of
chloro- and methylbenzoate was the presence of both the meta and ortho pathways a disadvantage for competitiveness. Outside these ranges other attributes, such as high growth rates or short lag
periods, of a respective strain were even more essential for one strain to outcompete another.
Received: 13 February 1998 / Received revision: 28 April 1998 / Accepted: 30 April 1998 相似文献
11.
According to the Centers for Disease Control and Prevention, biofilms cause 65% of infections in developed countries. Pseudomonas aeruginosa biofilm cause life threatening infections in cystic fibrosis infection and they are 1,000 times more tolerant to antibiotic
than the planktonic cells. As quorum sensing, hydrophobicity index and extracellular polysaccharide play a crucial role in
biofilm formation, extracts from 46 marine bacterial isolates were screened against these factors in P. aeruginosa. Eleven extracts showed antibiofilm activity. Extracts of S6-01 ( Bacillus indicus = MTCC 5559) and S6-15 ( Bacillus pumilus = MTCC 5560) inhibited the formation of PAO1 biofilm up to 95% in their Biofilm Inhibitory Concentration(BIC) of 50 and 60 μg/ml
and 85% and 64% in the subinhibitory concentrations (1/4 and 1/8 of the BIC, respectively). Furthermore, the mature biofilm
was disrupted to 70–74% in their BIC. The antibiofilm compound from S6-15 was partially purified using solvent extraction
followed by TLC and silica column and further characterized by IR analysis. Current study for the first time reveals the antibiofilm
and antiquorum-sensing activity of B. pumilus, B. indicus, Bacillus arsenicus, Halobacillus trueperi, Ferrimonas balearica, and Marinobacter hydrocarbonoclasticus from marine habitat. 相似文献
12.
Pseudomonas sp. strain M285 immobilized on diatomaceous earth beads was used to remove 3,5,6-trichloro-2-pyridinol (TCP) from industrial
wastewater. Batch studies showed that immobilized Pseudomonas sp. strain M285 mineralized [2,6- 14C]TCP rapidly; about 75% of the initial radioactivity was recovered as 14CO 2. Transformation of TCP was inhibited by high concentrations of salt, and addition of osmoprotectants (proline and betaine
at 1 mM) did not reduce the adverse effect of salt. TCP-containing wastewater (60–140 mg/l) was passed through columns containing
immobilized Pseudomonas sp. strain M285 at increasing flow rates and increasing TCP concentrations; TCP removal of 80%–100% was achieved. Addition
of nutrients, such as glucose and yeast extract, retarded TCP degradation. Growing cell cultures were found to be better inocula
for immobilization than resting cells.
Received: 5 February 1996 / Received last revision: 12 August 1996 / Accepted: 24 August 1996 相似文献
13.
Pseudomonas strain Ptm + grew on α-hexa-chlorocyclohexane (HCH, CAS no. 319846), using it as the sole source of carbon and energy. In a replacement-culture
study, with the non-insecticidal α-HCH, γ-HCH (CAS no. 58899) was the first metabolite noticed at 6 h, and transient accumulation
of insecticidal γ-HCH occurred for up to 18 h. Although delta- (CAS no. 319868) and beta-isomers (CAS no. 319857) were also
detected, their concentrations were very low. By 18 h of incubation, about 23% of the α-HCH added was transformed into the
gamma-isomer. Subsequently, the concentration of γ-HCH in the medium fell. Thin-layer chromatography, gas chromatography,
gas chromatography-mass spectrometry and mosquito-larval bioassay analyses confirmed the formation of γ-HCH. This was associated
with the formation of three more metabolites.
Received: 6 April 1999 / Received revision: 3 August 1999 / Accepted: 6 August 1999 相似文献
14.
Wild-type Streptomyces sp. strains, able to utilise both naturally occurring and synthetic organophosphonates, were isolated. High levels of inorganic
phosphate were necessary for their growth in complete medium as well as in medium, supplemented with phosphonates as the sole
carbon or nitrogen source. Isolate StA expressed detectable enzymatic activity against 2-aminoethylphosphonate in vivo. Streptomycete
StC had a surprising ability to degrade N-phosphonomethylglycine (glyphosate) in a phosphate-independent manner via C–P bond cleavage accompanied by sarcosine formation.
Received: 5 January 1999 / Received revision: 8 March 1999 / Accepted: 14 March 1999 相似文献
15.
A pentachlorophenol(PCP)-degrading Pseudomonas sp. strain UG30 was encapsulated in κ-carrageenan for use in PCP degradation. Free and encapsulated cells were compared for
their ability to dechlorinate and mineralize 100–800 μg/ml sodium pentachlorophenate in broth. Dechlorination was measured
with a chloride ion electrode, and mineralization was measured by 14CO 2 evolution from radiolabelled [U- 14C]PCP. Free and encapsulated Pseudomonas sp. UG30 cells mineralized up to 200 μg/ml and 600 μg/ml PCP, respectively, after 21 days. Encapsulation of UG30 cells provided
a protective effect, allowing dechlorination and mineralization of high levels of PCP to occur.
Received: 3 May 1996 / Received revision: 4 September 1996 / Accepted: 13 September 1996 相似文献
16.
The growth adaptability to increasing concentration of the biocide 2-phenoxyethanol (PE) was determined in Pseudomonas aeruginosa PAO1 ( P.a.) as part of efforts to understand and control the biocide tolerance and its effect on cross-resistance to other biocides
and resistance to antibiotics. After repeated subculturing in media containing increasing sub-minimum-inhibitory PE concentration,
P.a. exhibited an adaptive resistance indicated by two-fold increase in MIC at the 10th passage. The resistance was stable and
remained after passaging the strain in further 7 successive passages in PE-free growth media. The strain showed cross-resistance
towards dissimilar biocides and displayed increased susceptibility to antibiotics, which was not influenced by the presence
of the efflux inhibitor ‘carbonyl cyanide m-chlorophenyl hydrazone’. Outer membranes of adapted strain showed altered protein profile when examined by SDS-PAGE. 相似文献
17.
The present work was devoted to the study of the biosorption capacities of various microbial species ( Bacillus subtilis, Pseudomonas aeruginosa, Ralstonia metallidurans CH34 previously Alcaligenes eutrophus CH34, Mycobacterium smegmatis, Saccharomyces cerevisiae) for ions of the lanthanide gadolinium (Gd 3+). The uptake by sand of this element was also measured. Saturation curves and Scatchard models were established for all biosorbants
used in this work. The results enabled us to determine the binding affinities and the maximum capacities for biosorption of
Gd 3+, which ranged from 350 μmol g −1 for B. subtilis to 5.1 μmol g −1 for S. cerevisiae. This study demonstrated the usefulness of optimisation of experimental conditions in biosorption investigations. Experimental
results showed that biosorption could be influenced by the growth stage and by the composition of the growth medium of microbial
cells. Finally, particular attention was given to the transfer of gadolinium ions from a loaded sand to a bacterial suspension.
Received: 8 November 1999 / Received revision: 3 February 2000 / Accepted: 4 February 2000 相似文献
18.
The long-term influence of silicone oil 200 cSt (SO200) and 2, 2, 4, 4, 6, 8, 8-heptamethylnonane (HMN) on the cell surface
hydrophobicity (CSH) of a hexane-degrading Pseudomonas aeruginosa strain and a toluene-degrading Pseudomonas putida strain was assessed in two-phase partitioning bioreactors under batch and continuous operation. CSH was evaluated using a
modified BATH method based on optical density (CSH OD) and colony-forming unit (CSH CFU) measurements. In the presence of HMN, P. aeruginosa turned hydrophobic over the time course as shown by the gradual increase in CSH OD (61 ± 1%) and CSH CFU (53 ± 3%) under batch degradation and in CSH OD (49 ± 0%) under continuous operation. However, P. putida turned hydrophobic only under continuous operation (CSH OD = 28 ±2% {\hbox{CS}}{{\hbox{H}}_{\rm{OD}}} = 28 \pm 2\% ). On the other hand, no significant CSH enhancement was observed in both Pseudomonas strains in the presence of SO200. These results suggested that CSH is species, non-aqueous phase, and cultivation mode dependant,
and an inducible property of bacteria. Maximum hexane elimination capacities increased by 2 and 3 in the presence of SO200
and HMN, respectively. Based on the absence of CSH in P. aeruginosa in the presence of SO200, the higher elimination capacities recorded were likely due to an improved hexane mass transfer
(physical effect). However, in the presence of HMN, a direct hexane uptake from the non-aqueous phase (biological effect)
might have also contributed to this enhancement. 相似文献
19.
A two-phase organic/aqueous reactor configuration was developed for use in the biodegradation of benzene, toluene and p-xylene, and tested with toluene. An immiscible organic phase was systematically selected on the basis of predicted and experimentally
determined properties, such as high boiling points, low solubilities in the aqueous phase, good phase stability, biocompatibility,
and good predicted partition coefficients for benzene, toluene and p-xylene. An industrial grade of oleyl alcohol was ultimately selected for use in the two-phase partitioning bioreactor. In
order to examine the behavior of the system, a single-component fermentation of toluene was conducted with Pseudomonas sp. ATCC 55595. A 0.5-l sample of Adol 85 NF was loaded with 10.4 g toluene, which partitioned into the cell containing 1 l
aqueous medium at a concentration of approximately 50 mg/l. In consuming the toluene to completion, the organisms were able
to achieve a volumetric degradation rate of 0.115 g l −1 h −1. This system is self-regulating with respect to toluene delivery to the aqueous phase, and requires only feedback control
of temperature and pH.
Received: 16 November 1998 / Received revision: 28 March 1999 / Accepted: 9 April 1999 相似文献
20.
Pseudomonas aeruginosa secretes an extracellular lipase (EC 3.1.1.3), which has been isolated from culture media of either industrial fermentation
of wild-type P. aeruginosa PAC1R or an overexpressing P. aeruginosa strain carrying a plasmid with the cloned lipase gene. Both culture supernatants contained enzymatically active lipase protein,
as demonstrated by determination of hydrolytic activity using p-nitrophenylpalmitate and 1,2- O-dilauryl- rac-glycero-3-glutaric acid resorufin ester as substrates and analysis by sodium dodacyl sulphate/polyacrylamide electrophoresis
and Western blotting. Immobilization by entrapment into chemically inert hydrophobic silica gels was tested with crude enzyme
preparations. A matrix consisting of tetramethoxysilane and propyltrimethoxysilane at a molar ratio of 1 : 5 yielded the highest
enzyme activity as determined by esterification of lauric acid with 1-octanol in isooctane. The biotechnological potential
of P. aeruginosa lipase to catalyse the kinetic resolution of chiral compounds was tested by enantioselective acylation of two different model
compounds, racemic 1-phenylethanol and 2-pentylamine. Both compounds were acylated with high efficiency giving enantiomeric
excess rates of more than 99% for the alcohol and 96% for the amine with an average conversion rate of 50%. These results
demonstrated that P. aeruginosa lipase is an extremely useful enzyme for application in synthetic organic chemistry.
Received: 5 February 1996/Received revision: 1 April 1996/Accepted: 15 April 1996 相似文献
|