background: among all common techniques in sitedirectedmutagenesis, λ red recombinase system has beenwidely used to knock out chromosomal genes in bacteria. in thismethod, there is always the risk of dna linear digestion byhost's restriction enzymes that leads to the low frequency ofrecombination. objectives:to overcome this, we constructeda recombinant vector to disrupt phop gene in salmonella...

Notl linking clones are valuable for ordering of OW fragnents fractionated by Pulsed f ield gel electrophoresis(l) and especially Interested in that they are often associated with transcribable genes(2,3). To faci l i tate the isolation of Notl linking clones, we have devised a method which based on the insertion of Kanamycin cassette bearing Notl sites at both ends into cleavable Notl sites of...

Treponema denticola has been recognized as an important oral pathogen of the "red complex" bacterial consortium that is associated with the pathogenesis of endodontal and periodontal diseases. However, little is known about the virulence of T. denticola due to its recalcitrant genetic system. The difficulty in genetically manipulating oral spirochetes is partially due to the lack of antibiotic ...

A new set of broad-host-range promoter-probe vectors has been constructed. One subset contains the pVS1 and p15a replicons and confers resistance to either gentamicin or kanamycin. The other set contains the broad-host-range replicon from pBBR1 and confers resistance to kanamycin, tetracycline, ampicillin, or spectinomycin/streptomycin. Both plasmid sets are highly stable and are maintained wit...

An attempt was made to knockout the Escherichia coli C29 lacI gene with a kanamycin resistance cassette isolated from the plasmid pACYC177. This process used the lambdared recombinase system to allow for homologous recombination, and subsequent insertion of the kanamycin cassette into the lacI gene. The E. coli C29 cells were initially transformed with pKD46, which contains the lambda-red recom...

there are many techniques to knock out directed genes in bacteria, some of which have been described in salmonella species. in this study, a combination of soeing pcr method and the λ red disruption system were used to disrupt phop gene in wild type and standard strains of salmonella typhimurium. three standards pcr and one fusion pcr reactions were performed to construct a linear dna including...

In this paper, the construction and evaluation of a chromosomal expression platform (CEP), which allows controlled gene expression following ectopic integration into the chromosome of Streptococcus pneumoniae, is described. CEP is based on the well-studied maltosaccharide-inducible system. To facilitate integration at CEP, a plasmid, pCEP, capable of replication in Escherichia coli, but not in ...

Despite recent success in transforming various thermophilic gram-type-positive anaerobes with plasmid DNA, use of shuttle vectors for the expression of genes other than antibiotic resistance markers has not previously been described. We constructed new vectors in order to express heterologous hydrolytic enzymes in our model system, Thermoanaerobacterium saccharolyticum JW/SL-YS485. Transformed ...