Let’s suppose you think of bacteria – the bad kind – as assailants marching through your veins single-file, like an army on parade. If you were to think that way, you’d be wrong. It seems bacteria don’t do single much. They don’t make themselves that vulnerable.
According to a new study in Proceedings of the National Academy of Sciences, most of the world’s bacteria exist in communities. These communities are known as biofilms. And according to Harvard researchers – who recently investigated the biofilm of a bacterium called B. subtilis – biofilm can be nearly impenetrable.
These researchers report that the magic ingredient in biofilm – known as ECM – is like concrete. It helps bacteria stick to surfaces – everything from our teeth to oil wells to municipal plumbing. The ECM also protects bacteria from water, gas, and, of course, antibiotics.
Researchers already knew that biofilm was tough. They just didn’t know how tough. The following is a technical explanation of what they found (or skip down one paragraph for a simpler explanation):
Bacillus subtilis biofilm colonies and pellicles are extremely nonwetting, greatly surpassing the repellency of Teflon toward water and lower surface tension liquids. The biofilm surface remains nonwetting against up to 80% ethanol as well as other organic solvents and commercial biocides across a large and clinically important concentration range. We show that this property limits the penetration of antimicrobial liquids into the biofilm, severely compromising their efficacy.
In other words, biofilm is a lot like Teflon. It can stick to things, but things can’t stick to it. That’s how biofilm protects bacteria to the extreme. Thanks to the biofilm, bacteria don’t get wet. In fact, not even gases can penetrate biofilm, these scientists found. The toughness of biofilm presents real trouble for people with persistent bacterial infections, or people just trying to deal with a nasty sink clog caused by bacterial build-up.
On the other hand, scientists now know more about the microscopic concrete – ECM – that holds biofilm together. They know that it highly resists getting wet. And that’s important information.
These remarkable properties of B. subtilis biofilm, which may have evolved as a protection mechanism against native environmental threats, provide a new direction in both antimicrobial research and bioinspired liquid-repellent surface paradigms.
Translation: Harvard researchers have now learned something new and important about biofilms, which means that next-gen antimicrobials are more likely to be engineered to penetrate them. That’s good news if you have a bacterial infection.
Beth Lebwohl researches, writes and helps produce science content in audio and video formats for EarthSky. She is one of the authors on EarthSky.org, a script-writer for our podcasts, and helps host our English science podcasts in 90-second, 8-minute and 22-minute formats. Beth came to EarthSky in 2006 from the American Museum of Natural History's Department of Astrophysics, where she was surrounded by some of the greatest telescope-building, equation-wielding, code-writing physicists of our time. And they made her think . . . this science thing . . . it's pretty cool.