Algae invades a select party

Modern definitions of microbiology exclude most multicellular animals and plants but include other sub-microscopic organisms, especially prions, viruses and bacteria. Microbial Diversity by Oladele Ogunseitan makes clear its scope in the title and is an exceptionally good introductory text for all biological disciplines. It will be of use to students throughout their degree courses. Everything is in its place in a refreshingly readable way and, by not shirking complex biochemistry, the text does not patronise the student. The historical overview of the subject, the concept of microbial species, study techniques and a comprehensive review of the significance of microbiology from genetic evolution to interactions with eukaryotes make this book a must for any biologist's library.

Two substantial chapters deal with microorganisms' role in the cycling of major nutrients, carbon, nitrogen, phosphorus and sulphur. These chapters demonstrate the author's knowledge in dealing with microbial distribution on a global scale as well as the details of methane production by anaerobes. Ogunseitan's is as up to date as a textbook can be, including issues such as BSE and microbial aspects of global environmental change. He also demonstrates his understanding when underlining the importance of and contemporary measurement techniques applied to the biodiversity of microbes. The appendices incorporate a sound glossary and a list of sequenced genomes of microbial species with web references.

Freshwater Microbiology addresses a gap in the limnological literature that needed filling. However, unlike Ogunseitan's book, David Sigee's definition of microbiology does not restrict itself to the prokaryotes. As a consequence, his book reads like so many algal textbooks, and less than a quarter of this text is what I had hoped to read.

Sigee sets out to cover all the scales and types of freshwaters, lakes, ponds, rivers and estuaries and the habitats within. This produces simplistic, repetitive description of processes and characteristics. He also attempts to include the whole spectrum of microscopic organisms, viruses, bacteria, fungi, algae and zooplankton. This coverage is appropriate for general limnology texts but here leaves the reader wanting more detail relevant to freshwater systems. An area that might have been described in more detail is the benthic regions of lakes, rivers and ponds where redox conditions are critical in anaerobic microorganisms' influence on nutrient cycling. For the palaeo-ecologist, preservation of eukaryote sub-fossils and chemical signatures is strongly regulated by microbial activity and these are among the key indicators of environmental change incorporated in sediments - areas referred to in the final chapter.

Not all is disappointment though. Boxed examples in case studies are relevant and topical. Diagrams are generally clear and relevant, and tables are informative. The bibliography is substantial and the many references are current and appear after the final chapter - a style I personally approve of.

Tony Andrew is lecturer in environmental science and biology, Ulster University.