References

Microorganisms in Toxic Metal-Polluted Soils 345
metals on microbial communities is relatively limited despite extensive research.
Clearly, the complexity of interactions between metal species and
soilcomponents,aswellasbetweenmetalspeciesandmicroorganisms,
are major factors as are the limitations of chemical and biological techniques
that can be meaningfully applied. Laboratory and short-term field
experimentation may provide extensive information although this often
has limited relevance to natural and contaminated natural environments.
The lack of meaningful baseline data and ignorance of kinetic changes in
metal speciation, microbial communities and soil structure and composition
can also hamper studies of long-term and historically contaminated
sites. Pure culture studies may be open to the usual predictable criticisms,
although in the area of metal–microbe interactions, fundamental data obtained
have been of paramount importance, having wide relevance to our
understanding of prokaryotic and eukaryotic biology in a wider context, including
molecular and cell biology, genetics, physiology and biochemistry,
as well as providing insights into natural roles and potential in environmental
biotechnology. It is likely that novel and developing molecular and
genomic techniques for characterising microbial communities and their
functions will catalyse important steps forward in our understanding of
metals and microbial communities as well in the soil in general. As genomic
information on environmentally relevant microorganisms becomes
available along with reliable techniques for, e.g. DNA extraction, phylogenetic
analysis, cell imaging, biolabelling and use of marker molecules,
improvements in understanding should be marked and will serve to reconcile
important areas of laboratory and field-based research. Future studies
are also dependent on an interdisciplinary approach involving all aspects
of biology, chemistry, mathematical modelling, mineralogy, and geochemistry,
for example: the complexity of the soil environment demands this.
There is a lot of work to be carried out before daylight appears over the
(soil) horizon!
Acknowledgements. Theauthorgratefullyacknowledgesresearchsupport
from the Biotechnology and Biological Sciences Research Council, the Natural
Environment Research Council, the Royal Societies of London and
Edinburgh, and British Nuclear Fuels plc.
References
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Aoyama M, Nagumo T (1997a) Effects of heavy metal accumulation in apple orchard soils
on microbial biomass and microbial activities. Soil Sci Plant Nutrition 43:601–612