The average human being is the unconscious host of millions of microorganisms. They are present in our hair, on our skin, in exhaled air and saliva, and in our clothing. Fortunately, however, the vast majority of those microscopic passengers do not represent a threat either to our own health or to that of others with whom we come into contact. Indeed, many of these organisms are actually beneficial, serving as a defensive force to protect us from attack by their pathogenic cousins and other supportive activities. In areas where food is prepared, pathogens present on workers and on work surfaces are a constant threat, for which the use of ATP monitoring systems is now being seen as one of the most important components of hygiene and quality control within the food industry.

The technique employed for this purpose has its basis in a natural phenomenon displayed by a number of living creatures, including protozoa, a few species of bacteria, certain marine creatures such as the sea pansy, and a number of beetles. However, the example with which most of us are likely to be familiar has to be the firefly. All of these creatures produce, specialised enzymes which, for convenience, may all be included under the single umbrella term “luciferase”. Although individual enzymes may utilise differing mechanisms, all result in the production of visible light. The same is true of the reagents used in ATP monitoring systems.

In order to adapt this form of bioluminescence for in vitro use in the detection of microorganisms, it was necessary to develop a reagent containing a suitable enzyme and the luciferin substrate required to initiate the reaction, but lacking one essential component. The missing substance would then need to be one present in any organism that might contaminate the workspace and, unless eliminated, threaten the quality and the potential safety of foodstuffs and other consumable items, such as beverages and medicines. As the name given to these tests implies, the substance missing from the reagents but present in the bacteria and detected by ATP monitoring systems, is adenosine triphosphate.

Produced only by living cells, ATP is the primary means with which to capture, store, and transport the energy used to drive many chemical reactions in cells and readily detect the luciferase reaction. Although areas used to prepare food in factories or restaurants should normally undergo rigorous cleansing with disinfectant products, and personal hygiene is enforced, oversights occur, as does accidental contamination. When swabbing the handlers, the work surfaces, and any machinery or utensils used, and rinsing the swabs in the reagent mixture, these monitoring systems generate light in the presence of ATP. Its intensity can then be quantified using a calibrated reading device to provide a measure of the overall contamination. Where rinse water may also need to be tested, the sampling procedure may vary, but the principle remains the same.

Food hygiene is a vital component of the ongoing effort by manufacturers and suppliers to ensure quality, and to safeguard the health of the consumer. Without reliable equipment and proven test procedures, such efforts would be ineffective. Neogen is a company with a lengthy history of success in developing innovative food safety solutions. In South Africa, its ATP monitoring systems are available from IEPSA.

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