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Pseudomonas putida
About: Pseudomonas putida is a research topic. Over the lifetime, 6854 publications have been published within this topic receiving 230572 citations.
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TL;DR: Pseudomonas putida CSV86 exhibited diauxic growth on aromatic compounds plus glucose, with utilization of aromatics in the first log phase and of glucose in the second log phase, suggesting that de novo protein synthesis was essential.
Abstract: Pseudomonas putida CSV86, a naphthalene-degrading organism, exhibited diauxic growth on aromatic compounds plus glucose, with utilization of aromatics in the first log phase and of glucose in the second log phase. Glucose supplementation did not suppress the activity of degrading enzymes, which were induced upon addition of aromatic compounds. The induction was inhibited by chloramphenicol, suggesting that de novo protein synthesis was essential. Cells showed cometabolism of aromatic compounds and organic acids; however, organic acids suppressed glucose utilization.
94 citations
TL;DR: Investigations were made into the utility of DNA hybridization in conjunction with a microdilution most-probable-number procedure for the enumeration of Rhizobium spp.
Abstract: Investigations were made into the utility of DNA hybridization in conjunction with a microdilution most-probable-number procedure for the enumeration of Rhizobium spp. and Pseudomonas putida in soil. Isolates of Rhizobium spp. and P. putida carrying the transposon Tn5 were added to sterile and nonsterile Burbank sandy loam soil and enumerated over time. Soil populations of rhizobia were enumerated by colony hybridization, most-probable-number-DNA hybridization procedure, plate counts, plant infectivity most probable number, and fluorescent antibody counts. Population values compared well for all methods at 5 and 30 days after the addition of cells, although the fluorescent antibody method tended to overestimate the viable population. In nonsterile soil, most-probable-number-DNA hybridization procedure enumerated as few as 10 P. putida Tn5 cells g of soil-1 and 100 R. leguminosarum bv. phaseoli Tn5 cells g of soil-1 and should have utility for following the fate of genetically engineered microorganisms released to the environment. Among the Kmr isolates containing Tn5, approximately 5% gave a dark, more intense autoradiograph when probed with 32P-labeled pGS9 DNA, which facilitated their detection in soil. Hybridization with a pCU101 probe (pGS9 without Tn5) indicated that donor plasmid sequences were being maintained in the bacterial chromosome. Transposon-associated antibiotic resistance was also utilized as a phenotypic marker. Tn5 vector-integrate mutants were successfully enumerated at low populations (10 to 100 cells g of soil-1) in soil by both phenotypic (Kmr) and genotypic (DNA probe) analysis. However, determination of the stability of Tn5 or Tn5 and vector sequences in the bacteria is necessary.
94 citations
TL;DR: The σ54‐dependent Pu promoter of the TOL plasmid pWWO of Pseudomonas putida becomes activated by the prokaryotic enhancer‐binding XyIR protein when cells encounter m‐xylene in the medium, and the exponential silencing of Pu is caused ultimately by changes in the activity of the factor itself.
Abstract: Summary
The σ54-dependent Pu promoter of the TOL plasmid pWWO of Pseudomonas putida becomes activated by the prokaryotic enhancer-binding XyIR protein when cells encounter m-xylene in the medium. However, even in the presence of the aromatic inducer, Pu activity is silenced in vivo during rapid exponential growth of the cells in rich medium. Various elements known to be involved in the control of the transcriptional activity of the promoter were examined to ascertain the mechanism by which expression of Pu is limited during the exponential phase of growth. A truncated and fully constitutive XyIR derivative deleted of its signal reception N-terminal domain was found to be subjected to the same exponential silencing as the wild-type XyIR when exposed to m-xylene. This indicated that the phenomenon is not due to a late activation of XyIR by the aromatic effector. A Pu variant in which the integration host factor (IHF)-binding site had been functionally replaced by a statically curved DNA segment showed the same induction pattern, thus ruling out variations in the intracellular levels of IHF changes during growth as the element responsible for the inactivity of Pu in rapidly growing cells. On the contrary, overproduction of the σ54 factor allowed Pu expression during exponential phase. As σ54 protein levels remained approximately constant during growth, the exponential silencing of Pu could be caused ultimately by changes in the activity of the factor itself. This effect may not be exclusive to Pu, but could be a general co-regulation mechanism in σ54-dependent promoters that connects transcription of a specific set of genes with the general physiological status of the cells.
94 citations
TL;DR: Biochemical and genetic assays showed that conditional expression of the entire enzyme set allowed the engineered bacteria to adopt an anoxic regime that maintained considerable metabolic activity, underscore the value of P. putida as a versatile agent for biotransformations able to function at progressively lower redox statuses.
94 citations
TL;DR: The putP gene was homologous to the putP genes of several prokaryotic microorganisms, and its gene product is an integral inner-membrane protein involved in the uptake of proline, suggesting that in P. putida, both enzymatic steps for proline conversion to glutamic acid are catalyzed by a single polypeptide.
Abstract: Pseudomonas putida KT2442 is a root-colonizing strain which can use proline, one of the major components in root exudates, as its sole carbon and nitrogen source. A P. putida mutant unable to grow with proline as the sole carbon and nitrogen source was isolated after random mini-Tn5–Km mutagenesis. The mini-Tn5 insertion was located at the putAgene, which is adjacent to and divergent from the putPgene. The putA gene codes for a protein of 1,315 amino acid residues which is homologous to the PutA protein of Escherichia coli, Salmonella enterica serovar Typhimurium,Rhodobacter capsulatus, and several Rhizobiumstrains. The central part of P. putida PutA showed homology to the proline dehydrogenase of Saccharomyces cerevisiae and Drosophila melanogaster, whereas the C-terminal end was homologous to the pyrroline-5-carboxylate dehydrogenase of S. cerevisiae and a number of aldehyde dehydrogenases. This suggests that in P. putida, both enzymatic steps for proline conversion to glutamic acid are catalyzed by a single polypeptide. The putP gene was homologous to the putP genes of several prokaryotic microorganisms, and its gene product is an integral inner-membrane protein involved in the uptake of proline. The expression of both genes was induced by proline added in the culture medium and was regulated by PutA. In a P. putida putA-deficient background, expression of bothputA and putP genes was maximal and proline independent. Corn root exudates collected during 7 days also strongly induced the P. putida put genes, as determined by using fusions of the put promoters to ′lacZ. The induction ratio for the putA promoter (about 20-fold) was 6-fold higher than the induction ratio for the putPpromoter.
94 citations