You may not be familiar with the term “biofilm”; however, biofilms are around us everywhere in our rooms, offices and even in our own bodies. By scientific definition, a biofilm is microbes (bacteria, algae, yeast or fungi, protozoa, and viruses, hereafter called “bugs”) that grow collectively in adhesive polymers (mainly extracellular polymeric substances) on live or non-live surfaces. You may have already seen different forms of biofilms, for example, green coatings on rocks, and white films on the top of juices in open glasses left standing for several days. Sometimes you can also feel biofilms as slimy coatings on the inner surfaces of faucets and slippery materials on the floor in a shower room. Most times, however, you cannot see biofilm directly with your naked eyes. On a clean-looking surface, like a stainless steel counter top in a kitchen, the stainless steel is shining but very likely not biofilm free. Using different microscopes, scientists can see them and you may find dispersed cell aggregates in young biofilms and sometimes find peaks, valleys, caves, or tunnel-like structures in mature biofilms.
Bugs or microbes have existed on this planet for eons. Forming biofilms is one of the mechanisms they use to protect themselves in the stressful environment so they can survive. These stress factors include limited food sources, lack of water, UV light from the sun, and chemicals you use daily to kill them, etc. Some scientific studies have found that biofilms can be 1000 times more resistant to antibiotic or biocide killing. When bugs form biofilms, microbial cells secrete different kinds of polymers into the environment and use these materials to build a “house”-like structure, and thus they even “talk” more with each other; therefore, they can keep some of the biofilm cells protected even from direct UV or other germicidal killing, prevent some chemicals from getting inside, keep moisture in the structure to maintain their life, and change their physiology to cope with the stress. Once the environment becomes favorable, they may disperse and start to multiply as quickly as possible and occupy another territory.
What are the concerns?
On environmental surfaces, different kinds of bugs can form biofilms together in a community. Some of them can cause corrosion of certain materials and leave spots on a table, contaminate the water you drink and food you prepare, produce odors in rooms from air conditioners, harbor and protect pathogens making people sick and cause other problems in our daily life. However, it is extremely difficult to get rid of them and kill biofilms. Scientists and engineers in universities and industries have tried very hard to develop different antimicrobials and different chemical formulas of cleaning products to control biofilms; however, effectiveness of these products varies and some even bring new concerns such as pollution of the environment and development of super-bugs. After the surface is properly cleaned and disinfected, just a few cells left can start to form biofilms again and cycles go on. Therefore, it is critical to kill remaining cells as much as possible.
What are the options?
In order to reduce biofilms as much as possible, different approaches should be used depending on the application; but in most cases a combination of physical and/or chemical means is necessary to achieve the desired cleaning effect. It is like brushing your teeth using sonic brushes and tooth paste. Ultrasonic cleaning can break biofilm structures and disperse microbial cells then chemicals can penetrate easily and kill cells without the protection from a biofilm matrix. Also, steam vapor technology is very promising in that it combines both physical dispersal and disinfection functions. The dry steam generated can easily break the barrier of biofilm structures and kill cells inside biofilms. A study performed in the laboratory in the Department of Environmental Health at the University of Michigan using a novel steam disinfection system developed by Advanced Vapor Technologies, Seattle, WA (AVT) equipped with proprietary Thermal Accelerated Nano Crystal Sanitation (TANCS) technology found that the steam can rapidly kill biofilms formed by different bugs (>99.95 % killing efficiency) with only a 3 second treatment. However, to kill the same biofilms using commercially available chemical cleaning products may require 10 minutes or more. In addition, this technology uses only tap water to generate steam for cleaning and killing biofilms without any apparent chemical residuals left, and thus may have a wide application in different places such as healthcare, foodservice, hospitality, education, and other facilities.
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