Genetic Manipulation 215exchange 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
in to the growing nucleotide chain. If the error in the nascent 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
specified organism is a very powerful technique which is relatively new and
certainly in constant development, sometimes 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 macro-
scopic; principally higher plants and animals, commonly described as transgenics.
The latter term refers to the principle of deliberate transfer of a gene from one
organism to another in which it is not normally resident. This earns the incom-
ing 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 genetic engineering, which in principle are almost boundless,
given sufficient resources, but because of cost. It is a principal factor as the
technology and research to produce transgenic organisms attract an inherently
high price. While such a situation may be sustainable by pharmaceutical compa-
nies 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 appli-
cations of environmental 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 micro-organism structured to improve the rate
of degradation of a pollutant, its performance may be exemplary in laboratory
conditions but when it is applied in bio-augmentation it is in competition with