Pseudomonas putida

About: Pseudomonas putida is a research topic. Over the lifetime, 6854 publications have been published within this topic receiving 230572 citations.

Characterization of two surface-localized antigenic sites on porin protein F of Pseudomonas aeruginosa.

Abstract: A rapid colony immunoblot screening procedure was used to demonstrate the surface localization of porin protein F on bacterial colonies of Pseudomonas aeruginosa. By this method, we demonstrated that protein F was accessible to four different specific monoclonal antibodies in a wide variety of both mucoid and nonmucoid P. aeruginosa strains. Controls were performed to demonstrate that, using this procedure, only surface-exposed epitopes bound monoclonal antibodies and that nonspecific binding of monoclonal antibodies either to cells lacking protein F or to mucoid exopolysaccharide did not occur. Monoclonal antibodies MA4-4, MA2-10, and MA4-10, specific for protein F, also interacted with colonies of Pseudomonas putida and Pseudomonas syringae, whereas the protein F specific monoclonal antibody MA5-8 interacted only with P. aeruginosa strains. Using the above-named monoclonal antibodies, we investigated the antigenic structure of protein F. Monoclonal antibodies MA4-4, MA2-10, and MA4-10 bound to 29–31 kil...

The TOL plasmid pWW0 xylN gene product from Pseudomonas putida is involved in m-xylene uptake.

Abstract: The upper operon of the TOL plasmid pWW0 of Pseudomonas putida encodes a set of enzymes involved in the conversion of toluene and xylenes to their carboxylic acid derivatives. The last gene of the upper operon, xylN, encodes a 465-amino-acid polypeptide which exhibits significant sequence similarity to FadL, an outer membrane protein involved in fatty acid transport in Escherichia coli. To analyze the role of the xylN gene product, xylN on TOL plasmid pWW0 was disrupted by inserting a kanamycin resistance gene, and the phenotypes of P. putida harboring the wild-type and xylN mutant TOL plasmids were characterized. The growth of P. putida harboring the wild-type TOL plasmid was inhibited by a high concentration of m-xylene, while that of P. putida harboring the xylN mutant TOL plasmid was not. The apparent Ks value for the oxidation of m-xylene in intact cells of the xylN mutant was fourfold higher than that of the wild-type strain, although the TOL catabolic enzyme activities in cell extracts from the two strains were almost identical. We therefore presume that the xylN gene product is a porin involved in the transport of m-xylene and its analogues across the outer membrane. Western blot analysis confirmed the localization of XylN in the outer membrane.

Physiological responses of Pseudomonas putida to formaldehyde during detoxification.

Abstract: Pseudomonas putida KT2440 exhibits two formaldehyde dehydrogenases and two formate dehydrogenase complexes that allow the strain to stoichiometrically convert formaldehyde into CO(2). The strain tolerated up to 1.5 mM formaldehyde and died in the presence of 10 mM. In the presence of 0.5 mM formaldehyde, a sublethal concentration of this chemical, the growth rate decreased by about 40% with respect to growth in the absence of the toxicant. Transcriptomic analysis revealed that in response to low formaldehyde concentrations, a limited number of genes (52) were upregulated. Based on the function of these genes it seems that sublethal concentrations of HCOH trigger responses to overcome DNA and protein damage, extrude this toxic compound, and detoxify it by converting the chemical to CO(2). In strains bearing mutations of the upregulated genes we analysed growth inhibition by 1.5 mM HCOH and killing rates by 10 mM HCOH. Mutants in the MexEF/OprN efflux pump and in the DNA repair genes recA and uvrB were hypersensitive to 10 mM HCOH, the killing rate being three to four orders of magnitude higher than those in the wild-type strain. Mutants in other upregulated genes died at slightly higher or at similar rates to the parental strain. Regarding growth inhibition, we found that mutants in glutathione biosynthesis, stress response mediated by 2-hydroxy acid dehydrogenases and two efflux pumps of the MSF family were unable to grow in the presence of 1.5 mM HCOH. In an independent screening test we searched for mutants which were hypersensitive to formaldehyde, but whose expression did not change in response to this chemical. Two mutants with insertions in recD and fhdA were found which were unable to grow in the presence of 1.5 mM HCOH. The recD mutant was hypersensitive to 10 mM HCOH and died at a higher rate than the parental strain.

Improving the sensitivity of bacterial bioreporters for heavy metals.

Abstract: Whole-cell bacterial bioreporters represent a convenient testing method for quantifying the bioavailability of contaminants in environmental samples. Despite the fact that several bioreporters have been constructed for measuring heavy metals, their application to environmental samples has remained minimal. The major drawbacks of the available bioreporters include a lack of sensitivity and specificity. Here, we report an improvement in the limit of detection of bacterial bioreporters by interfering with the natural metal homeostasis system of the host bacterium. The limit of detection of a Pseudomonas putida KT2440-based Zn/Cd/Pb-biosensor was improved by a factor of up to 45 by disrupting four main efflux transporters for Zn/Cd/Pb and thereby causing the metals to accumulate in the cell. The specificity of the bioreporter could be modified by changing the sensor element. A Zn-specific bioreporter was achieved by using the promoter of the cadA1 gene from P. putida as a sensor element. The constructed transporter-deficient P. putida reporter strain detected Zn(2+) concentrations about 50 times lower than that possible with other available Zn-bioreporters. The achieved detection limits were significantly below the permitted limit values for Zn and Pb in water and in soil, allowing for reliable detection of heavy metals in the environment.