Who you gonna call? Slimebusters!
In one of the first potential applications of synthetic biology, which aims to design and build useful biomolecular systems, researchers have engineered viruses to attack and destroy the surface “biofilms” that harbor harmful bacteria in the body and on industrial and medical devices. Bacterial biofilms can form almost anywhere, such as on your teeth if you don’t brush. When they accumulate in hard to reach places such as the insides of food processing machines or medical catheters, however, they become persistent and dangerous sources of infection. The bacteria excrete a variety of proteins, polysaccharides, and nucleic acids that together with other materials form an extracellular matrix, a slimy layer that encases the bacteria. Traditional remedies such as antibiotics are not as effective on these bacterial biofilms as they are on free-floating bacteria. In some cases, antibiotics may even encourage bacterial biofilms to form.
For a bacteriophage to be effective against a biofilm, it must both attack the bacteria in the film and degrade the extracellular matrix. Recently, a group of researchers discovered several phages in sewage that meet both criteria because they carry enzymes capable of degrading the biofilm’s extracellular matrix. In the most recent edition of PNAS, researchers have defined a modular system that allows scientists to design phages to target specific biofilms. As a proof of concept, they used their strategy to engineer T7, an Escherichia coli-specific phage, to express dispersin B (DspB), an enzyme known to disperse a variety of biofilms. They found that their engineered T7 phage eliminated 99.997% of the bacterial cells in the biofilm, an improvement of more than a hundred-fold over the original phage.
Dispersing biofilms with engineered enzymatic bacteriophage. PNAS USA 2007 104: 11197-11202
Question: Are there “good” biofilms that we DON’T want destroyed?
Yes, in sewage treatment works for example. I imagine that these engineered viruses would be quite tightly controlled if they were ever to be used, but if they did gain access to the environment, I strongly suspect that although they might initially alter the composition of some environmental biofilms, the diversity of environmental microbes is such that after a relatively short time there would be little if any effect.
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