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Keep on growing! Maintaining Cultures for Biotechnology and Industry

edited by Jennie C. Hunter-Cevera and Angela Belt, Academic Press, I996.

US$39.95 (xii + 263 pages) ISBN 0 12 361946 7

Another book on the maintenance of cultures? Well, yes! However, this particular volume has a lot to recommend it. Firstly, it is wide ranging in the diversity of subjects that it covers - from algae to protozoa, to bacteria and fungi, through to plant and animal cells and their viruses. Secondly, the high quality of each contribution indicates that the contributors are experts in their fields.

In the first chapter, biological deposition requirements are considered, and there is a discussion on the Budapest Treaty along with a relatively up-to-date list (as of August 1991) of International Depository Authorities under the Treaty.

The remainder of the book discusses different types of organism. One particular strength is the excellent layout and user-

friendliness of the format. Each chapter starts with a discussion of biodiversity from a taxonomic and phylogenetic viewpoint, and continues with an overview, of classification, examples of industrial and economic importance, and information concerning characterizing cultures. This information provides a good background to each type of microorganism, and there are comprehensive lists of references for further reading.

Various preservation methods are discussed in some detail; topics not only include freezing and lyophilization, but techniques such as air drying and continuous propagation. The importance of genetic stability is examined, and attention is paid to the maintenance of vital cell characteristics and patent deposits. Cryopreservation

methods, in particular, are very well described by someone who obviously has experience, rather than by a scientist who has simply reviewed papers; this is evident because of the detail that is provided about methods and protocols. For example, required concentrations of cryopreservants are described, together with efficient freezing programs to maintain the maximum viability of the cultures. In the case of the cryopreservation of bacteria, tips on how to optimize freezing procedures in the absence of state-of-the-art programming equipment are outlined. In many cases, the protocols are sufficiently detailed that they could be directly worked from, although up-to-date references are still provided.

Another usefhl element of the book is the fact that each chapter concludes with a list of culture collections relating to the microorganisms discussed.

In conclusion, this guide is extremely well thought-out and put together, and it would be an asset in any laboratory.

Alan Doyle and Philip Packer CAMR (Centre for Applied Microbiology

and Research), Porton Down, Salisbury, UK SP40JG.

Hot stuff Biotechnology Handbooks, Volume 9: Thermus Species

edited by Richard Sharp and Ralph HTilliams, Plenum Press, 1995. US875. O0

(:,'iv + 233 pa~es) ISBN I 306 44925 0

To researchers in the fields of microbiology, biochemistry and genetics of thennophilic microorganisms, this text is a nmst. To those who fall outside this rather specialized group, a typical response may well be 'Thermus who?' However, the accusation of specificity can be levelled at any research treatise, and this no more than most.

Thermus species rose to pronfinence in the early 1970s as the first examples of extremely themmphilic bacteria (i.e. those that have growth optima around 75°C). First isolated by Thomas Brock in 1969, their existence in

environments that were hitherto presumed sterile opened a new- world to scientists of many interests - the world of intrinsically thennostable biological macromolecules.

Possibly as a result of their virtually ubiquitous existence in therlnal environments (from New Zealand to Iceland, in natural thermal springs and geysers, in industrially heated wastewaters, in domestic water heaters and in nfid- Atlantic deep-sea hydrothermal vents), Thermus species have retained a high level of popularity as a target for researchers from many disciplines. This popularity,

has been retained despite the discoveries in the 1980s of hyperthermophilic (i.e. for w'hich optimum grow'th temperatures are between 85°C and 105°C) Archaea and in the early 1990s of hyperthennophilic Bacteria ('Ilwrmotoga and Aquifex species). Because of their higher growth temperatures, these organisms produce proteins with substantially higher intrinsic thennostabilities than those typically found in Wher17111s.

The ease with which Thermus can be isolated and cultured, reviewed comprehensively in the chapter by Gudni Alfredsson and Jakob Kristjansson, is probably also a factor contributing to the popularity of the organism. Aerobic tbrmentation at around 75°C producing mult i~am quantities of biomass per litre, is highly attractive, particularly if compared with Archaeal fermentations and the difficulties inherent in anaerobic fermentation at 95°C, which often yield biomass at less than 0.1g 11.

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book reviews

The content of Tony Williams' and Richard Sharp's volume is generally comprehensive, although only limited mention is made of the ecology of Thermus. This may reflect the limited amount of recent work in this area. Sadly, the founder of the field and eminent microbial ecologist, Thomas Brock, turned his attention to other areas of microbiology in 1985.

Other chapters are both comprehensive reviews of the literature and useful working guides: I refer, for example, to the inclusion of the complete 16S rDNA sequence alignments for four Thermus species (tLalph Williams and Richard Sharp), and to the tables detailing the compositions of all the commonly used Thermus culture media (Richard Sharp, Doug Cossar and Ralph Williams). Both provide valuable and immediately accessible information for new workers in the field. Other chapters on cells and lipids (Milton da Costa), on Thermus genetics (Neil Raven) and on genetic manipulation (Tairo Oshilna) provide well-referenced reviews of the state of research in these areas.

It is interesting to note one particular area of research where Thermus has been left in the wake

of recent scientific advances. Despite the characterization of numerous Tkermus enzymes (Melanie Duffield and Doug Cossar) and the cloning and sequencing of a number of these, there are few examples of x-ray crystallographic structures of Thermus proteins. The accessibility, of homologues of higher thernlostability from hyperthermophilic Bacteria and Archaea has inevitably redirected the attentions of structural molecular biologists away from 77wrmus proteins to the hyperthermophilic examples. The latter provide the greatest increments of stability in comparison to mesophilic homologues and, therefore, potentially offer better model systems for the identification of the mechanisms of protein stabilization.

Thermus has, of course, become famous in biotechnology through the extensive use of Tkermus aquaticus YTI DNA polymerase (Taq polymerase) in PCR. It is saddening to realize that the legions of molecular biologists who routinely use Taq polymerase probably have no knowledge of the colourful history (and characters) that underpin the origin of this

most useful organism. Peter Bergquist and Hugh Morgan review the biotechnology of Thermus products in some detail, inevitably concentrating on Taq polymerase as the foremost example of thennophile commercialization. Unfortunately, they make no mention of another colourful episode in the current 'history' of 7hermus biotechnology (at the date of submission, the issue may not have been public knowledge), this being the on-going dispute over the Taq polymerase patent between Promega (Madison, WI, USA), and Hoffman-La Roche (Basel, Switzerland), who are current owners of the original Cetus patents and defendants in the litigation.

To conclude, I must suggest to all thermophiliacs that this slim text, packed with interesting and useful information (particularly if you are enamoured of Gram-negative non- sporulating aerobic therlnophiles), will be an indispensable complement to your personal library.

Don Cowan Department of Biochemistry and Molecular

Biology, University College London, Gower Street, London, UK WC1E 6BT.

(Email: don.cowan@ucl.ac.uk)

Publishers Please send details of books of interest to biotechnologists to:

TIBTECH Book Reviews, Elsevier Trends Journals, 68 Hills Road, Cambridge, UK CB2 1LA.

TIBTECH SEPTEMBER 1996 (VOL 14)