The mosaic-structured Vibrio cholerae genome points to the importance of horizontal gene transfer (HGT) in the evolution of this human pathogen. We showed that V. cholerae can acquire new genetic material by natural transformation during growth on chitin, a biopolymer that is abundant in aquatic habitats (e.g., from crustacean exoskeletons), where it lives as an autochthonous microbe. Transform...

The interaction between transformation and prophages of HP1c1, S2, and a defective phage of Haemophilus influenzae has been investigated by measurement of (i) the effect of prophage on transformation frequency and (ii) the effect of transformation on phage induction. The presence of any of the prophages does not appreciably alter transformation frequencies in various Rec(+) and Rec(-) strains. ...

In addition to natural competence, some Thermus thermophilus strains show a high rate of DNA transfer via direct cell-to-cell contact. The process is bidirectional and follows a two-step model where the donor cell actively pushes out DNA and the recipient cell employs the natural competence system to take up the DNA, in a hybrid transformation-dependent conjugation process (transjugation). Whil...

The Haemophilus influenzae Rd strain JG87 contains a single mini-Tn10kan insertion that causes a deficiency in the development of competence for genetic transformation. The DNA fragment containing this insertion mutation, as well as the wild-type locus, was cloned, mapped, and sequenced. The sequence contained an open reading frame for a protein of 224 amino acids with a predicted Mr of 25,152....

Acinetobacter sp. strain BD413 (= ATCC 33305), a nutritionally versatile bacterium, has an extremely efficient natural transformation system. Here we describe the generation of eight transformation-affected mutants of Acinetobacter sp. strain BD413 by insertional mutagenesis. These mutants were found by Southern blot analysis and complementation studies to result from single nptII marker insert...

Naturally competent bacteria have the ability to take up free DNA from the surrounding medium and incorporate this DNA into their genomes by homologous recombination. In naturally competent Streptococcus pneumoniae, and related streptococcal species from the mitis phylogenetic group, the competent state is not a constitutive property but is induced by a peptide pheromone through a quorum-sensin...

In 1928, Griffith [1] reported that soluble substances from virulent pneumococcal cells trans‐ formed non-virulent pneumococcus to virulent forms. This substance has now been demon‐ strated to be DNA [2-4]. This is considered to be the first report on genetic transformation of bacteria by exogenous DNA. Subsequently, natural competence of Bacillus subtilis was re‐ ported in 1958 by Young and Sp...

The purpose of the present study was to analyze the effective components of educational transformation in agricultural higher education system in Iran by a mixed study method. The statistical population includes all faculty members (N=361) teaching in agricultural college of Tehran, Tarbiat Modares and Shiraz University, and a sample of 186 faculty members (n=186) were selected by stratified ra...

UNLABELLED Porphyromonas gingivalis is a Gram-negative anaerobe that resides exclusively in the human oral cavity. Long-term colonization by P. gingivalis requires the bacteria to evade host immune responses while adapting to the changing host physiology and alterations in the composition of the oral microflora. The genetic diversity of P. gingivalis appears to reflect the variability of its ha...

Some variables in the Bacillus licheniformis transformation system, such as inoculum size, initial cell density in transformation medium, and time of optimal competence, have been explored, and a methodology has been developed to obtain greater reproducibility and maximal competence for transformation. The transformation system in B. licheniformis has been shown to be similar to that of B. subt...