Genetic Manipulation - Environmental Biotechnology: Theory and Application - page 213

likely to occur as a result of an error in DNA replication. This is far less likely to
be the most prominent source of mutation in nature, as the microbes are constantly
in close proximity with other organisms and, consequently, the opportunity for
exchange of genetic material is enormous. In fact the process of DNA replication
has a very high fidelity, the reasons for which are obvious. An increased rate
of error may be forced upon the organism, speeding up the rate of mutation,
by including a mutagen in the growth medium. A mutagen is a chemical which
increases the rate of error in DNA replication, often by causing a very limited
amount of damage to the DNA such that the DNA polymerase, the enzyme
responsible for synthesising DNA, is unable to determine the correct base to add
into the growing nucleotide chain. If the error in the naescent strand cannot be
recognised and corrected, the fault becomes permanent and is handed on through
the generations.
Manipulation of Bacteria by Genetic Engineering
Genetic manipulation by the deliberate introduction of defined genes into a spec-
ified organism is a very powerful, established technique in constant development,
some times at phenomenal rates of progress. The techniques have produced some
exciting hybrids in all areas of research, both microscopic; bacteria and fungi,
usually described as recombinants, and macroscopic; principally higher plants
and animals, commonly described as transgenics. The latter term refers to the
principal of deliberate transfer of a gene from one organism to another in which
it is not normally resident. This earns the incoming gene the title of 'foreign'.
Some examples of these which are relevant to environmental biotechnology will
be discussed later in this chapter.
Some of the developments are of great potential interest and represent some
exciting and innovative work. However, it must be said that, in practice, a very
tiny proportion of all endeavour in the name of environmental biotechnology
has, or is likely to have in the future, a direct reliance for its effectiveness on
the type of recombinants and transgenics currently being developed. This is not
because of the limits of GE, which in principal are almost boundless, given suffi-
cient resources, but because of cost. It is a principal factor as the technology and
research to produce transgenic organisms attracts an inherently high price. While
such a situation may be sustainable by pharmaceutical companies and perhaps to
a lesser extent, agribiotechnology companies possibly able to command a high
return on sales of the product, it is rarely sustainable in applications of environ-
mental technology. Few commercial organisations are excited at the prospect of
spending a large proportion of their income on waste disposal, for example and
will normally only do so when absolutely necessary.
There are other factors which affect the suitability of transgenic organisms in
this science due to current requirements for containment. In addition, the way
in which such a recombinant is utilised may cause problems of its own. For
example, if the recombinant is a microorganism structured to improve the rate