Control the growth of biofilms.

As you may know, biofilms formed on the surfaces of food processing equipment pose a safety threat because they are difficult to remove or inactivate. They can contaminate foods even if the equipment is routinely cleaned. Microbial biofilms found on surfaces create billions of dollars yearly in equipment damage, product contamination, energy losses and medical infections. Conventional approaches used to kill bacteria, such as antibiotics and disinfection, are often ineffective with biofilm bacteria.

The large doses of antimicrobials required to rid systems of biofilms are undesirable environmentally, and perhaps not allowed by some environmental regulations. So new strategies based on a better understanding of how bacteria attach, grow and detach are urgently needed by many industries.

The bacteria that attach to a biofilm are able to resist sanitizers and other antimicrobial agents, unlike planktonic or free-living bacteria. So it's important to properly detect and control these films. One way to do this is to use bioreactors and fomenters in which the flow rate of nutrients can be constant for a specific period of time.

There are several ways to measure and study bacteria in biofilms. Such techniques utilize microscopic beads, or use scraping, swabbing or rinsing processes. You can monitor the formation of biofilms using microscopy, spectroscopy or nuclear magnetic resonance systems. But these approaches are somewhat expensive and time-consuming.

What are needed are less expensive techniques, as well as those that are rapid, more sensitive to bacteria and which are able to function on-line and in real time. A biosensor fits the bill. The device can be attached to a surface on which a biofilm has attached itself. It'll enable you to monitor the films on-line. A biosensor may help in quantifying the development of bacterial biofilms, thereby quantifying risk assessment and extending operating cycle times.

In the food processing environment, biofilms are sources of pre- or post-processing contamination. Cleaning them with detergents, scrubbing food contact surfaces and applying sanitizers are effective ways to control biofilms. Moreover, when designing food-processing equipment, the appropriate type of materials should be carefully selected to prevent microbial adhesion to the surface of equipment.

Further information. Sadhana  Ravishankar, National Center for Food Safety and Technology, 6502 S. Archer Rd., Summit-Argo, IL 60501; phone: [phone]; fax: [phone]; URL: www.ncfst.iit.edu.