Pollution and Pollution Control - Environmental Biotechnology: Theory and Application - page 81

organic sulphur, including heterotrophes (Rai and Reyniers 1988) like Pseu-
domonas , Rhizobium and the fungi Paecilomyces and chemolithotrophes like
Sulfolobus , mentioned earlier. These all act aerobically, but there is evidence to
suggest that some microbes, like Desulfovibrio can employ an anaerobic route
(Holland et al . 1986). While the use of such model substrates has some validity,
since thiophenes are the major organic sulphur components in coal, how well
their breakdown accurately reflects the situation for the real material remains
much less well known.
A range of putative bioreactor designs for desulphurisation have been put for-
ward, involving treatment systems of varying complexity, which may ultimately
provide an economic and efficient method for removing sulphur from these fuels
prior to burning. However, the state of the art is little advanced beyond the lab-
oratory bench and so the benefits of large-scale commercial applications remain
to be seen.
Biological Control
The use of insecticides and herbicides, particularly in the context of agricultural
usage, has been responsible for a number of instances of pollution and many of
the chemicals implicated are highly persistent in the environment. Though there
has been a generalised swing away from high dosage chemicals and a widespread
reduction in the use of recalcitrant pesticides, worldwide there remains a huge
market for this class of agrochemicals. As a result, this is one of the areas
where biotechnological applications may have significant environmental impact,
by providing appreciably less damaging methods of pest management. The whole
concept of biological control took a severe blow after the widely reported, dis-
astrous outcome of Australia's attempts to use the Cane Toad ( Bufo marinus )to
control the cane beetle. However, in principle, the idea remains sound and con-
siderable research effort has gone into designing biological systems to counter
the threat of pests and pathogens. Some of these, in respect of soil-borne plant
pathogens and biopesticides, are discussed elsewhere in this work and, accord-
ingly, do not warrant lengthy reiteration here.
The essence of the specifically environmental contribution of this type of bio-
intervention lies in its ability to obviate the need for the use of polluting chemicals
and, consequently, leads to a significant reduction in the resultant instances of
contamination of groundwater or land. However, one of the major limitations on
the effective use of biocontrols is that these measures tend to act more slowly than
direct chemical attacks and this has often restricted their use on commercial crops.
In fairness, it must be clearly stated that biotechnology per se is not a central, or
even necessary, requirement for all of biological control, as many methods rely on
whole organism predators, which, obviously, has far more bearing on an under-
standing of the ecological interactions within the local environment. However,
the potential applications of biotechnology to aspects of pest/pathogen/organism