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The enzymes -that came in from the cold

On the frozen expanses of the Antarctic, researchers collect thousands of micro-organisms, characterised by their extreme biodiversity and of particular interest to the food and detergent industries.
For numerous industrial sectors, the isolation, characterisation and engineering of proteins produced by bacteria living at temperatures close to 0C open up the prospect of the availability of enzymes that are fully active at low temperatures. In this emerging area of research on "psychrophile" micro-organisms, Europe has rapidly become a world leader thanks to the coordinated research carried out under the Eurocold concerted action and the Coldzyme project.


Enzymes - proteins which catalyse the fundamental biochemical reactions of all living cells - are used extensively by industry in applications as diverse as preparing food, formulating detergents and detecting pollutants using biosensors. Most of the organisms that provide the enzymes currently in use live in environments where the temperature ranges from 30C to 40C, and their effectiveness is highly temperature-sensitive. Consequently, many enzymatic processes require heating that is expensive - and, in certain cases, harmful to the organoleptic qualities of a foodstuff - or simply not feasible. Ensuring high-performance enzymatic activity at low temperatures therefore represents an important industrial imperative. And where does the solution lie? Out in the cold, of course.

The incredible biodiversity of the Antarctic
There are a wide variety of ecosystems on earth, all of which, in differing degrees, have been colonised by living organisms. Researchers have discovered numerous micro-organisms that are perfectly adapted to diverse extreme conditions - be it temperatures in the region of 100C, acid or alkaline environments, or very high salinity levels. The Antarctic, the second largest continent on earth where the temperature rarely rises above zero, is no exception to this rule. It is here on the Antarctic expanses, at the interface between the sea and the icefields, and also on the icefields themselves, that Nicholas Russell and Charles Gerday have collected thousands of micro-organisms - bacteria, in particular, but also yeasts - which they are studying as part of the Coldzyme project.

"The discovery of the extreme biodiversity of these psychrophile micro-organisms is one of the unexpected spin-offs of our work," stresses Nick Russell of the University of London and coordinator of the project. "I've got more than a thousand different bacteria in my cold storage rooms," says Charles Gerday of the University of Lige (Belgium). "At present we have identified 15 or so different types. We do not know much about these organisms, and it is difficult to make comparisons. This complicates the task of taxonomic research."

The primary objective of this vast project, which coordinates all European research in this area, is to study the enzymes with a view to understanding the rules governing their adaptation to the cold. And we have not had to wait long for the results.

Computer-generated image of a protein isolated in a bacterium from the Antarctic icefields, in the process of digesting starch (alpha-amylase). The reptilian structure of the protein enables it to remain flexible and to function at very low temperatures. Such proteins are now being developed to operate new biotechnology cold processes.

New biotechnological line
The researchers have focused their work on the type of enzymatic activity where known equivalents exist in normal bacteria and which are of genuine interest in the field of biotechnological applications (see table). "Impressive progress has been made," Charles Gerday points out enthusiastically. "In the space of a year we have resolved the three-dimensional structure of two major enzymes, alpha-amylase and a calcium-zinc protease, and two patents have been applied for."

This research has enabled us to understand how enzymes are able to adapt to the cold. The explanation lies not in any difference in the three-dimensional structure of the enzymes of psychrophiles but in the flexibility of the protein. The functioning of an enzyme necessarily entails deformations in its structure to permit a preliminary investigation of the substrate, the reaction proper, and then the release of the modified substrate. These minor conformational changes are very temperature-sensitive and, in order for them to occur in cold conditions, the protein therefore needs to be extremely flexible. This is the exact opposite of what happens in the case of organisms living at high temperatures (close to 100C), where the proteins have to be extremely rigid to prevent their spatial conformation from being totally destroyed by heat-induced agitation. "A further aim of the project is to lay the foundations of a new biotechnological line," Nick Russell goes on. Numerous proteins are in the process of being cloned, and the researchers have succeeded in producing mutants of certain enzymes, which have already been tested by the partner manufacturers. Even if the enzymes provide the requisite levels of activity, new adaptations will still be necessary before detergent products and food additives incorporating Antarctic enzymes can be placed on the market.

The research is being followed with interest by the manufacturers who make up the Microbiology Industrial Platform. Negotiations on bilateral agreements involving filing applications for patents and their exploitation are currently under way. Thanks to psychrophile bacteria, new ground is being broken in the area of cell factories, whereby the emphasis is placed on cold shock proteins, special genetic control systems, specific membrane compositions, different excretion mechanisms, etc. The potential industrial applications are legion and, if we take Nick Russell's word for it, "psychrophiles are hot stuff". Given that all the skills required have been coordinated under the aegis of the Community programmes, Europe now has a big lead over its American and Japanese rivals.

Some of the enzymes studied under the Coldzyme project and their possible fields of application:
ALPHA-AMYLASE breadmaking, textiles, brewing, detergents
CELLULASE stonework cleaning, "bio-polishing"
BETA-GALACTOSIDASE elimination of lactose from milk
LIPASES detergent additives, flavourings
PROTEASES detergent additives, meat tenderising
XYLANASES breadmaking




Project Title:  
Molecular characterisation of cold-active enzymes from psychrophilic micro-organisms as the basis for novel biotechnology, Coldzyme


Contract Reference: BIO4CT960051 BIO4CT950017

CORDIS databaseFor more information on this project,
go to the Cordis database Record 1-2