Lasse Korsholm Poulsen

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Use of the green fluorescent protein (Gfp) from the jellyfish Aequorea victoria is a powerful method for nondestructive in situ monitoring, since expression of green fluorescence does not require any substrate addition. To expand the use of Gfp as a reporter protein, new variants have been constructed by the addition of short peptide sequences to the(More)
The physiology of Pseudomonas putida KT2442 with respect to growth and carbon starvation was studied. During the transition from growth to nongrowth, the cell shape changes from cylindrical to spheric, a change which is accompanied by reductions in cell size, DNA and ribosome content, and the rate of total protein synthesis. In addition, a pattern of(More)
As a representative member of the toluene-degrading population in a biofilter for waste gas treatment, Pseudomonas putida was investigated with a 16S rRNA targeting probe. The three-dimensional distribution of P. putida was visualized in the biofilm matrix by scanning confocal laser microscopy, demonstrating that P. putida was present throughout the(More)
Fluorescent oligonucleotide probes targeting rRNA were used to develop an in situ hybridization technique by which the spatial distribution of Escherichia coli in the large intestines of streptomycin-treated mice was determined. Single E. coli cells were identified in thin frozen sections from the large intestines by the use of a probe specific for E. coli(More)
The relF gene in Escherichia coli is related to the hok gene on plasmid R1. Both genes encode small proteins which, when overexpressed in E. coli lead to collapse of the membrane potential and cell death. A third gene, designated gef, which encodes a homologous cell-toxic protein, has been isolated from E. coli DNA. Both gef and relF are transcribed in E.(More)
Growth rates of Escherichia coli BJ4 colonizing the large intestine of streptomycin-treated mice were estimated by quantitative hybridization with rRNA target probes and by epifluorescence microscopy. The ribosomal contents in bacteria isolated from the cecal mucus, cecal contents, and feces were measured and correlated with the ribosomal contents of(More)
An avirulent, streptomycin-resistant Salmonella typhimurium strain, SL5319, and its lipopolysaccharide (LPS)-deficient mutant strain, SL5325, differ in their ability to colonize the large intestines of streptomycin-treated mice. When fed to mice independently, the strains colonize equally well, but when fed together, the LPS-deficient mutant is outcompeted(More)
The FimH adhesin of type 1 fimbriae has been tested as a display system for heterologous protein segments on the surface of Escherichia coli. This was carried out by introduction of restriction site handles (BglII sites) in two different positions in the fimH gene, followed by in-frame insertion of heterologous DNA segments encoding two reporter sequences.(More)
We describe post-transcriptional regulation of the chromosomal gene, gef, from Escherichia coli. The gef gene is a member of a gene family consisting of the chromosomal gef and relF genes from Escherichia coli and the hok, flmA, srnB, and pndA genes, which are situated on conjugative plasmids. All the genes encode small, toxic proteins of approximately 50(More)
The seven members of the hok killer gene family in Gram-negative bacteria are described here. The members of this gene family have been sequenced and include hok/sok from plasmid R1, flm and srnB from plasmid F, pnd from plasmids R483 and R16, and gef and relF, which are located on the Escherichia coli chromosome. The killer proteins encoded by these loci(More)