........ published in NEWSLETTER # 57
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........ published in NEWSLETTER # 57
MOLECULAR ECOLOGY OF AQUATIC MICROBES
by Dr. I. Joint, Plymouth Marine Laboratory, Plymouth (U.K.)
The development of molecular biology in the last forty years has been one of the most rapid of any scientific discipline. Molecular techniques are now adopted widely, from medical research to forensic science. Aquatic microbial ecologists increasingly use these methods and, as a result, are developing a much clearer understanding of important ecological problems, such as phylogenetic diversity, the molecular basis of physiological acclimation and how organisms sense and respond to changes in their environment. This book (NATO ASI SERIES G38) reviews progress in this new field of ecological research and assesses how emerging molecular techniques might solve some important problems in ecology. In addition to molecular ecology, a number of chapters review current knowledge and highlight problems in freshwater and marine microbial ecology.
The book covers a number of broad themes. The introductory chapters consider the opportunities offered to aquatic ecology by molecular biology and demonstrate how an understanding of the molecular basis of photosynthesis has provided novel techniques to measure oceanic primary production. Chapters examine the role of aquatic microbes in biogeochemical cycles in the water column and sediment, with emphasis on the microbial loop and the nitrogen cycle. Microbial communities in marine and freshwater systems are characterised in chapters on the importance of mixotrophy, species succession and the impact on phytoplankton taxonomy of molecular biology. Several chapters then examine the response of microbes to changes in environmental conditions, the molecular basis of signal transduction mechanisms, and how novel molecular approaches allow investigation of nutrient limitation in phytoplankton and bacteria.
The rest of the book concerns specific biological processes and groups of micro-organisms. Standard microbiological approaches have largely failed in ecology because the majority of aquatic bacteria cannot be clustered in the laboratory. Molecular approaches have resulted in important advances in the characterisation of natural bacterial communities. New approaches to measuring microbial growth rates are described and several chapters deal with molecular characterisation of bacteria involved in major biogeochemical processes such as methane oxidation and nitrogen fixation. In recent years, viruses have been shown to be adundant in marine systems and consideration is given to the role of virus infection in limiting productivity. The final chapter contrasts differences between organisms in natural populations and those in culture and questions how representative organisms are in pure culture. Given that microbes in nature probably act as consortia, this is surely one of the most important questions for microbial ecologists to answer in the future.
This book offers a timely assessment of the impact of molecular biology on aquatic microbiology. It highlights the great potential of many molecular techniques for the study of natural bacteria in the sea, rivers and lakes.
Reference books: C362, G25, G27, G38