The Gangs of Sink City

By Lauren Hoskin

Unbeknownst to the average person, biofilms are encountered on a daily basis. These microbiologist’s nightmares are the slime living beneath your toilet seat, the muck in your drain pipes, the gunk around the taps and even the dental plaque on your teeth. Millions of bacteria and other microbes including fungi and algae join forces to become one giant super-resistant army. And if that’s not enough to put you off then consider that these deadly gangs can be up to 300 times more resistant to chlorine and other bug-tackling chemicals than lone bacteria.

Bacterial biofilms form at boundaries between solid and liquid substances, for example, between a ceramic sink basin and the water flowing out of the tap. Motile bacteria with swimming devices are able to easily move through liquid and attach themselves to solid surfaces. The newly attached bacteria form the base layer of the biofilm. They then undergo an accumulation phase during which non-motile bacteria floating through the water are recruited, and all the cells multiply. Multiplication rates are astounding – some biofilms may flourish from microscopic to macroscopic (easily seen by the human eye) in a matter of hours. During multiplication the witty cells secrete a sticky substance called Exopolysaccharide, EPS for short. EPS is a mixture of excess DNA, proteins and sugars that bind the microbes into a slimy clique. Unification gives the biofilm a real upper hand when times get tough; nutrients and signals are easily distributed through the layers, and outer cells help to protect the inner crowd. They can also effortlessly share resistance genes which help them to become immune to the toils of cleaning detergents and antibiotics.

Biofilms might not seem like much of a threat in daily life, but they can become extremely problematic in hospitals and workplaces, especially in light of increasing antibiotic resistant superbugs. Additionally they contaminate water supplies in developing countries, and can even sometimes be linked to common infections such as otitis media (common ear infection). Similarly, a build-up of dental plaque can form gum disease and tooth decay. However, regular cleaning is usually enough to ward off the average biofilm, allowing healthy individuals to be safe from these deadly gangs… for the moment at least….