Industrial Enzymes: Do Halophiles and Alkaliphiles Have a Role to Play?
‘Extremophile’ is an exceedingly imprecise term in microbiology, referring as it does to microbes inhabiting extreme environments. Not only is the term anthropocentric, it lumps together totally unrelated microorganisms purely on the basis of ecosystem or
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19.1 Introduction ‘Extremophile’ is an exceedingly imprecise term in microbiology, referring as it does to microbes inhabiting extreme environments. Not only is the term anthropocentric, it lumps together totally unrelated microorganisms purely on the basis of ecosystem or phenotype. Of all the phenotypic groups of prokaryotes generally categorized as belonging to the ‘extremophiles’, the (extreme) halophiles form an apparently coherent group that has enjoyed many decades of scientific research. Many salt-tolerant and salt-requiring microorganisms are instantly recognizable as inhabitants of distinctive (hyper)saline environments and their peculiar properties fascinated biochemists and microbiologists alike, long before the distinction between Archaea and Bacteria was recognized. The distinctive properties of halophiles has led to no shortage of innovative ideas for their technical application and exploitation and several reviews on this topic have appeared in recent years (Grant et al. 1998; Margesin and Schinner 2001). In spite of this, it is evident that few of these ideas have been realized in widespread and economical commercial practice. Even a cursory examination of the patent literature on extremophile microorganisms reveals that at least 20 % of these concern halophilic microbes, but not surprisingly perhaps most of these claim applications for bacteriorhodopsin. Even though commercial technical applications for bacteriorhodopsin are beginning to emerge, the reality is, despite many innovative ideas, halophiles have not yet made much impact on the commercial scene. There has been more impact from alkaliphilic microorganisms. Alkaliphiles are often to be found in high pH, alkaline environments such as soda lakes and these environments are usually somewhat saline. Their industrial relevance has also been reviewed (Horikoshi 1998).
A. Ventosa (Ed.) Halophilic Microorganisms © Springer-Verlag Berlin Heidelberg 2004
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B. E. Jones
19.2 Industrial Enzymes The most widespread commercial use of products and processes derived from halophilic and alkaliphilic microbes are in industrial enzymes and this is probably the largest economic sector at present. These are industrial products used on a large scale – in ton quantities – as process aids in various industrial processes in industries such as food processing, textile manufacture and the grain and starch processing industry. Additionally, industrial enzymes are used directly as active ingredients in consumer products like laundry detergents, or in animal feed to improve the nutritional value. Although accurate figures are often difficult to obtain and it is often unclear whether industrial analysts are referring to value in dollars or in volume, the industrial enzymes market is currently estimated to be worth between 1.5 and 1.8 billion US dollars. The four main commercial sectors are grain and starch processing, textiles, food and cleaning (Table 19.1). This chapter will concentrate on the use of enzymes in the cleaning and textile business areas, since thes
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