Biofilm & Quorum Sensing

 Did you know that bacteria make the antibacterial medications (antibiotics) we use? That's right! 

Bacteria in nature make antibiotics that enable it to outcompete other bacteria. 

Biofilm is one example of how different bacteria work together for survival. It is a structure made of one or more species of bacteria that adhere together and form a colony that is covered by a polysaccharide substance, or EPS (extracellular polysaccharide substance.) 

As the bacteria collect, they perform a few collective functions. First, they establish channels they use to communicate (using chemical information), share nutrients, and pass waste products. 

Note that some bacteria use waste products as their nutrients! Does that seem gross? It does until you stop and realize that WE do that all the time. The best example is oxygen. Oxygen is a waste product of photosynthesis, the process by which plants (and other photosynthetic organisms) convert water, carbon dioxide, and sunlight into stored energy. 

As the biofilm accumulates, it also senses the environment in which it has found itself. Different bacteria have different genetic properties, such as the types of enzymes and antibiotics they produce. Once they have accumulated that information, growth ensues.

They can also pass along genetic material through the channels that enables the group to take on that trait.

Once growth ensues, the biofilm will actually deliberately shed some of the cells which then form another biofilm, and so on.

Biofilm can be both pathogenic and symbiotic. While they form on our teeth and can cause tooth decay, biofilm can be found in the gut and are integral to our digestive system. 

However, the biofilm does not become helpful nor harmful right away. We go back to the idea that they consider their environment which has a direct effect on what genes are used - think about enzyme production; they may need certain enzymes in one environment both another type in a place that has different nutrition, water availability, or other environmental factor. When the bacteria have all communicated their agreement, they will suddenly activate. This agreement through chemical communication is called "Quorum sensing." 

If you want to watch a really cool video about Quorum Sensing, this TED Talk discusses it through the phosphorescence of certain squid. https://youtu.be/KXWurAmtf78