Natural transformation has significant effects on bacterial genome evolution, but the evolutionary factors maintaining this mode of bacterial sex remain uncertain. Transformation is hypothesized to have both positive and negative evolutionary effects on bacteria. It can facilitate adaptation by combining beneficial mutations into a single individual, or reduce the mutational load by exposing de...

Bacterial genomics is flourishing, as whole-genome sequencing has become affordable, readily available and rapid. As a result, it has become clear how frequently horizontal gene transfer (HGT) occurs in bacteria. The potential implications are highly significant because HGT contributes to several processes, including the spread of antibiotic-resistance cassettes, the distribution of toxin-encod...

Plasmid transformation of Escherichia coli is now a cornerstone of modern molecular biology, being widely utilized for cloning and amplifying DNA sequences. Its origins were set in the early 1970s with the discoveries that treatment of E. coli and Salmonella typhimurium (official designation, Salmonella enterica serovar Typhimurium) at 0°C in a solution of divalent cations, notably calcium chlo...

We present a new hypothesis for the selective pressures responsible for maintaining natural competence and transformation. Our hypothesis is based in part on the observation that in Bacillus subtilis, where transformation is widespread, competence is associated with periods of nongrowth in otherwise growing populations. As postulated for the phenomenon of persistence, the short-term fitness cos...

Natural competence for genetic transformation, i.e. the ability to take up DNA and stably integrate it in the genome, has so far only been observed in the bacterial kingdom (both in gram-negative and gram-positive species) and may contribute to survival under adverse growth conditions. Bacillus subtilis, the model organism for the Bacillus genus, possesses a well-characterized competence machin...

A broad-host-range cloning vector, pUI81, was constructed in vitro from plasmids RSF1010 and pSL25 (a pBR322 derivative) and used to assay for transformation in Rhodopseudomonas sphaeroides. Washing cells with 500 mM Tris was an effective means of inducing competence for DNA uptake. Transformation frequencies as high as 10(-5) (transformants per viable cell) have been achieved by incubating Tri...

In S. suis the ComX-inducing peptide (XIP) pheromone regulates ComR-dependent transcriptional activation of comX (or sigX) the regulator of the late competence regulon. The aims of this study were to identify the ComR-regulated genes and in S. suis using genome-wide transcriptomics and identify their function based on orthology and the construction of specific knockout mutants. The ComX regulon...

UNLABELLED Natural transformation by competent bacteria is a primary means of horizontal gene transfer; however, evidence that competence drives bacterial diversity and evolution has remained elusive. To test this theory, we used a retrospective comparative genomic approach to analyze the evolutionary history of Aggregatibacter actinomycetemcomitans, a bacterial species with both competent and ...

The efficiency of Agrobacterium-mediated transformation in plants depends on the virulence of Agrobacterium strains, the plant tissue culture conditions, and the susceptibility of host plants. Understanding the molecular interactions between Agrobacterium and host plant cells is crucial when manipulating the susceptibility of recalcitrant crop plants and protecting orchard trees from crown gall...

Intact yeast cells treated with alkali cations took up plasmid DNA. Li+, Cs+, Rb+, K+, and Na+ were effective in inducing competence. Conditions for the transformation of Saccharomyces cerevisiae D13-1A with plasmid YRp7 were studied in detail with CsCl. The optimum incubation time was 1 h, and the optimum cell concentration was 5 x 10(7) cells per ml. The optimum concentration of Cs+ was 1.0 M...