Biofilm Basics by Bob Henke of The Post Star
One of the most pervasive life forms is called biofilm. A biofilm is most easily understood by thinking of it as simply a slimy colony of bacteria. It turns out very few bacteria are actually free-living; more than 99 percent live in biofilms.
The nature of these biofilms is exceptionally variable. Some are actually moveable, with the whole group oozing about seeking good habitat. Others fasten to some host or strata and remain there, at times virtually impossible to remove. These little bacteria cities may be composed of a single species of bacteria or there may be several different types living together.
Each bacteria in these aggregations exudes a slippery, sugary substance that forms a case over them all, protecting them from attack by other unicellular animals as well as ensuring that any food produced by the group remains with the group. In some of the larger biofilms, the species involved may have complementary metabolisms, that is one species uses as food the materials excreted by others and vice versa.
Biofilms are found everywhere from on sheer rock faces at the top of mountains to plastic surgery implants. The cause of most childhood inner ear infections is a biofilm and biofilm infections ranging from surgical wound infections to heart valve infections kill more than 40,000 Americans annually, more than die from cancer.
The reason they are so troublesome is because most drugs cannot penetrate the biofilm’s tough exterior. The reason for this and the reason biofilms are so intrinsically dangerous is their ability to communicate and thereby keep all the colony residents working toward a single result.
The nature of this communication is at once fascinating and a critical research need. In simplest form, the communication is chemically based. The individual bacteria pump out streams of chemicals which are varied, depending on the message. Other bacteria receive, make note and take appropriate action before duplicating the chemical sonnet and sending it along. In this way they can change direction, change the permeability of the film to let in nutrients or let out waste products or perform a host of other activities.
One of the key chemical phrases researchers are investigating is called a quorum sensor. This is, simply put, how a bacterium knows it is not alone.
The quorum sensing process works like this: A bacteria routinely produces what is called an autoinducer chemical. When the bacteria in turn senses a great concentration of autoinducer chemical returning to it, meaning there are a lot of other bacteria nearby, the gene for biofilm production is turned on and all members of the cohort begin producing the impermeable covering. Inside an animal, this makes the colony invulnerable to attack from, for example, antibiotics given to cure the sinus infection the biofilm is causing.
If researchers can discover the exact chemical signature of this autoinducer, it may be possible to convince the bacteria they are all alone causing them to abandon the biofilm and travel about, making treatment of the malady much easier and straightforward.
This esoteric-seeming research could ultimately save millions of lives. I wish they could also find something that would make me quit communicating long enough to save mine.
Bob Henke may be contacted by mail c/o The Post-Star, email at firstname.lastname@example.org, on Twitter at @BobHenke, or on Facebook.
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