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some kind of modification(s) of the genome/DNA of the host organism, hence the term of genetically modified (recombinant) organism (GMO) emerges.What is the competent cellebased bacterial transformation about?

some kind of modification(s) of the genome/DNA of the host organism, hence the
term of genetically modified (recombinant) organism (GMO) emerges. It is also
important to notice that initially the genetic modification term would cover both
the naturally and laboratory conditioneassisted genetic modifications, while
currently it is more related to the laboratory-obtained transgenic organisms, containing a foreign piece of DNA (gene(s)) from other species.
How was the bacterial type of genetic modification discovered? Initially the
phenomenon describing the formation of GMOs was named genetic transformation
and was discovered accidently by Frederick Griffith in the 1920s as a natural phenomenon by which the host bacterial cell gains genetic material/genes from some molecules present in the culture media. At that time, we did not know much about the
chemical nature and the subcellular localization of the hereditary material. Griffith
was working with two Streptococcus pneumonia strains and showed that the nonvirulent strain got transformed into a virulent one when the sterilized virulent bacterial
lysate was introduced into the media of the nonvirulent strain. Much later it has
been demonstrated that such a genetic transformation implies the uptake of virulent
DNA fragments by the host nonvirulent bacterial cell from the culture media, leading
to a genetically recombined organism that acquires new trait(s). Moreover, it has also
been demonstrated that the abovementioned genetic transformation among identical
or different bacterial species is a seldom event as many bacterial cells are greatly
restricted in taking up free DNA fragments from a liquid environment.
What is the competent cellebased bacterial transformation about? It is also
interesting that since the 1970s, there have been developed novel laboratory methods
by which the so-called competent host bacterial cells could take up circular DNA
molecules like plasmids, and the efficiency of such bacterial transformations
increased significantly in such conditions or controlled ex situ environments. Before
transformation, the plasmid was cut open, and a foreign fragment of DNA, containing gene(s), could be incorporated by closing the plasmid back, resulting in a recombinant plasmid. It is worthwhile mentioning that Stephen Norman Cohen and
Herbert Boyer published in 1973 the first scientific article proving an outstanding
discovery for biology: obtaining a recombinant plasmid and ensuring the transfer
from one living organism to another, laying the foundations of DNA/gene cloning
that became one of the most powerful molecular methods (Cohen et al., 1973).
We must specify that this is different from the implicated DNA uptaking mechanisms seen in the case of Griffiths competent host types of bacterial transformations.
Moreover, the competent bacterial host strains were included into the molecular
cloning methodologies so that the bacterial host cells could efficiently incorporate,
replicate, and even express the plasmid-carried recombinant cloned gene(s) without
getting integrated into the major bacterial DNA/genome. Thus, the trespassing of a
biological barrier like the horizontal gene transfer (HGT, implying the movement of
genetic material between different species) represents a remarkable achievement in
the history of mankind, and it will open new challenging horizons accelerating the
development of life sciences. Accordingly, high throughput basic research programs
like genome projects (sequencing of the genomes of many species, including the
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CHAPTER 1 Why is genetic modification of interest