Changing aura of contamination
BIOLUMINESCENCE detection is changing the face of microbial contamination. A new biotechnology device is now being exploited worldwide to detect microbial contamination in industries ranging from cosmetics, to foodstuffs to pharmaceuticals.
According to a report in the Financial Times, London, about 2.5 billion such tests were performed worldwide last year, says Frost and Sullivan, the market research Organisation. But the new, rapid-testing methods account for only about 2.5 per cent of the testing.
Fireflies, glow worms and the phosphorescence of the sea are the .5 most common examples of bioluminescence, but the feature is present among many animals, plants, ftingi and bacteria. Living organisms produce light with an enzyme called luciferase.
Biotechnology companies have developed kits which use luciferase to measure adenosine triphosphate (ATP) - a naturally occuring ch 'emical which ftiels all biochemical reactions including luminosity. A small volume of the substance being tested is mixed with an enzyme reagent supplied with the kit. After a few minutes, the sample begins to produce light.
The intensity of the light is measured in a luminometer to measure the amount Of ATP present. This is extrapolated to give the number of microbes, or the total biological material present indicating whether bacteria or other contaminants are present in the sample.
The Financial Times report states that bioluminescence, however, has yet to find a significant application outside diagnostics and microbial testing. Gurdon Stewart, professor at the University of Nottingham, has used it successfully in research.
The lux gene, which confers the ability for luminescence, can be engineered into any organism, he says. A researcher may then follow the activity of a gene simply by the amount of light it produces.
Chris Evans, a director of Celsis International, a UK-based biotechnology company, says, "If Louis Past@ur was alive today he would feel quite at home in the modern microbiological quality assurance laboratory. Most of the tech- niques he used are still used today."
The same results can how be achieved within a few minutes. Bioluminescent tests are not only quicker, but they require little training for process operators, and they are often more accurate than conventional methods.
Martin Chaplin, professor, South Bank University, London, is one of the pioneers of bioluminescence research, working since the days when unwieldy high-voltage light measuring machines were required. He says: "As you are using an enzyme to detect ATP, you have a high degree of specificity ... it is theoretically possible to detect a single photon and therefore I molecule Of ATP."
Fleet Laboratories, a UK-based drug manufacturer, has been using Celsis detection systems for more than a year. The systems solve some basic production -problems, says Tony Hook, 1the firm's commercial manager. "How do you know that someone has, washed their hands? Conventioijally you swab someone's hand and it would take 3 to 4 days to find out how clean they are.
Now we can find out in a matter of minutes." There are now more than 40 companies which sell bioluminescence-based tests. In the commercially important area of microbiological quality assurance, there are only a handful of main players: Amersham, Biotrace and Celsis of the UK, and Lumac of the Netherlands.
Steve Genton, Lumac sales and marketing director, says: "It is vital for these tests to distinguish between microbial and other cells. In a sample, microbes may only be a tiny minority of the total biological material."
The tests can incorporate filters to screen any extraneous biological material and measure the microbe numbers. In some cases, like measuring the cleanliness of a surface, one only needs to know the amount of total biological material and filtration that is not used. Kits are now available for both requirements and the technology is getting easier to use.