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At least 865 records · Page 48Linked to original sources
PubMed2005

Stable transformation of Chromobacterium violaceum with a broad-host-range plasmid.

Stable transformants of Chromobacterium violaceum were obtained by high-voltage electroporation with a 7-kilobase binary plasmid. The technique was reliable, reproducible, and simple, with efficiencies of 10(5) transformants/microg of plasmid DNA. The electrical conditions that resulted in the highest efficiencies were short pulse length (4.4-4.5 ms) and high voltage (12.5 kV/cm). The numbers of transformants were almost the same during the growth exponential phase (variation at optical density) and resulted in the highest efficiencies at DNA concentration of 250 pg/ml. Saturation appeared to begin at 4 microg/ml of DNA. This method of C. violaceum transformation should enhance the genetic and biotechnological research by providing a valuable, widely used procedure of introducing DNA into this bacterium.

Chromobacterium↗
PubMed2001

Sequence analyses of a broad host-range plasmid containing ermT from a tylosin-resistant Lactobacillus sp. Isolated from swine feces.

Anaerobic bacteria resistant to the macrolide antibiotics tylosin and erythromycin were isolated from the feces of swine. One of the strains, 121B, was initially identified by 16S rDNA sequence analysis as an unknown Lactobacillus sp. The strain was found to contain at least two plasmids, one of which was capable of replicating and providing erythromycin and tylosin resistance to Bacillus subtilis, Streptococcus gordonii, and Escherichia coli. DNA sequence analyses of the 4,232-bp plasmid, p121BS, identified one open reading frame encoding a methylase gene highly similar (> 98% amino acid identity, > 99% DNA sequence identity) to the ermT gene from the Lactobacillus reuteri plasmid pGT633. This is only the second ermT gene to be reported. p121BS also contains two additional open reading frames with significant amino acid similarities to replication proteins from Lactobacillus and other Gram-positive bacteria.

Amino Acid Sequence↗
PubMed1996

The aggregation-mediated conjugation system of Bacillus thuringiensis subsp. israelensis: host range and kinetics of transfer.

The aggregation-mediated conjugation system in Bacillus thuringiensis subsp. israelensis encoded on the plasmid pXO16 is characterized by the formation of aggregates when Agr+ and Agr- cells are socialized in exponential growth. Using the aggregation phenotypes, we have identified potential recipients of the aggregation-plasmid pXO16 among Bacillus cereus, Bacillus subtilis, Bacillus megaterium, Bacillus sphaericus, and 24 subspecies of B. thuringiensis. We found 14 Agr- strains, i.e., potential recipients of the aggregation system encoded by plasmid pXO16. Five strains contained a conjugative apparatus of their own and were excluded from further examinations. To monitor the transfer of plasmid pXO16, we constructed a transposon insertion of the plasmid with Tn5401. The study of the plasmid transfer of pXO16::Tn5401 indicated the secretion of bacteriocins from both donor strain and recipient strains. Only one out of the nine strains examined was unable to receive the aggregation-plasmid pXO16 and express the aggregation phenotype and the conjugative abilities. It was found that the transfer of plasmid pXO16 to Bacillus thuringiensis subsp. israelensis Agr- strains was 100%. All recipients had acquired the aggregation-plasmid pXO16 and converted to the Agr+ phenotype.

Anti-Bacterial Agents↗
PubMed2004

Host range and specificity of an Argentinean isolate of the aquatic fungus Leptolegnia chapmanii (Oomycetes: Saprolegniales), a pathogen of mosquito larvae (Diptera: Culicidae).

An isolate from Argentina of the fungal mosquito pathogen Leptolegnia chapmanii (ARSEF 5499), was tested against 12 species of mosquito larvae and on species of non-target aquatic invertebrates and vertebrates. The mosquito species tested were Aedes aegypti, Anopheles sp., Culex apicinus, Cx. castroi, Cx. dolosus, Cx. pipiens, Cx. renatoi, Isostomyia paranensis, Ochlerotatus albifasciatus, Oc. crinifer, Psorophora cyanescens, and P. ferox. Mosquito larvae of 10 species were susceptible, with mortality rates from 10-100%. Two mosquito species Cx. renatoi and I. paranensis were not infected by Leptolegnia. None of the non-target fauna treated was infected by L. chapmanii with exception of members of the Family Chironomidae which were susceptible at low infection rates.

Animals↗
PubMed1993

Mutational analysis of the specific priming signal essential for DNA replication of the broad host-range plasmid RSF1010.

To analyze the RSF1010-specific priming mechanism, a library of randomly mutagenized ssiA sequences was constructed by chemical synthesis using mixed nucleotide phosphoramidites. Synthetic ssiA sequences with the single base-substitutions were assayed for the SSI activity in E. coli JM109 expressing RepB' primase. It was demonstrated that the activity of ssiA was damaged markedly by single base-substitutions within the possible stem-loop structure and its 3'-flanking region. It is conceivable that these domains are critical in recognition and primer synthesis by RepB' primase.

Base Composition↗
PubMed1986

Identification and analysis of genes for tetracycline resistance and replication functions in the broad-host-range plasmid pLS1.

The streptococcal plasmid pMV158 and its derivative pLS1 are able to replicate and confer tetracycline resistance in both Gram-positive and Gram-negative bacteria. Copy numbers of pLS1 were 24, 4 and 4 molecules per genome in Streptococcus pneumoniae, Bacillus subtilis and Escherichia coli, respectively. Replication of the streptococcal plasmids in E. coli required functional polA and recA genes. A copy-number mutation corresponding to a 332 base-pair deletion of pLS1 doubled the plasmid copy number in all three species. Determination of the complete DNA sequence of pLS1 revealed transcriptional and translational signals and four open reading frames. A putative inhibitory RNA was encoded in the region deleted by the copy-control mutation. Two putative mRNA transcripts encoded proteins for replication functions and tetracycline resistance, respectively. The repB gene encoded a trans-acting, 23,000 Mr protein necessary for replication, and the tet gene encoded a very hydrophobic, 50,000 Mr protein required for tetracycline resistance. The polypeptides corresponding to these proteins were identified by specific labeling of plasmid-encoded products. The tet gene of pLS1 was highly homologous to tet genes in two other plasmids of Gram-positive origin but different in both sequence and mode of regulation from tet genes of Gram-negative origin.

Bacillus subtilis↗
PubMed1989

Unidirectional transfer of broad host-range plasmid R1162 during conjugative mobilization. Evidence for genetically distinct events at oriT.

A segment of R1162 DNA containing genes for conjugative mobilization (Mob) and the origin of transfer (oriT) was integrated into the Escherichia coli chromosome. Bacterial genes were transferred in a polar fashion during conjugative mobilization of the integrated segment by a self-transmissible plasmid vector. The direction of transfer, together with the properties of mutated derivatives of oriT, indicate that initial cleavage of oriT, and subsequent religation after transfer, entail different mechanisms that can be distinguished genetically.

Base Sequence↗