Biofilms, The Biology of Slime: 1- Intro

When most people think of bacteria, they usually think of free floating cells, completely independent of each other. Most researchers until recently thought the same, however that’s not how most bacteria live outside the comforts of a microbiology laboratory!


Lick your teeth, can you feel that weird layer? That’s plaque, you have heard of that from your dentist and those Colgate toothpaste adverts. But what exactly is plaque, other than the thing that causes your teeth to rot and makes visits to the dentists so much fun? Plaque is bacteria, but in a very specialized mode of life called a biofilm! In fact dental plaques are the earliest biofilms to be described by Antoine van Leeuwenhoek in 16841. Biofilms are everywhere in nature and are the most predominate form of microbial life.



Biofilms in the environment- slimy bacterial cities2


They affect almost every aspect of our lives and are usually harmful, such as biocorrosion of water pipes, tooth decay, contamination of medical devices. However biofilms also have beneficial aspects to their biology, such as our gut microbiome, which aids our digestion and waste water treatment plants utilise biofilms to remove organics pollutants in the water. Biofilms also play a role in element cycles such as the carbon, nitrogen and iron cycles.


bf32Biofilms impact all areas of life, including human health3, corrosion and fouling of water mains4, agriculture and water treatment5


What exactly is a biofilm you may ask? A biofilms is a community of bacteria stuck in a self-produced slime known as the extra-cellular polysaccharide (EPS). The biofilm is usually attached to a surface such as the enamel of your teeth, the surface of a medical implant or the inside of a pipe, however the biofilm may be a free floating collection of cells in slime know as a bacterial floc. The bacterial members do not have to be of the same species, in fact they very often a community of different species working together or against each other in a race of survive and thrive in the real world.



Biofilm composition- bacteria in a slime!


Bacteria usually form a biofilm as it allows them to do all things a bacterial cells got to do to survive! Biofilms can trap water to help them survive in dry conditions and acts as a fortress, which the bacterial community can survive toxic assaults from anti-microbials such as bleach and antibiotics, which otherwise would kill free floating cells. Also as the bacteria cells are part of a much larger slime layer, they are difficult if not impossible for predators such as amoeba or our own white blood cells (macrophages) to ingest. Further bacteria can swap and exchange genes (like Pokémon) to give themselves a greater advantage.


How do biofilms develop? Biofilms undergo a general lifecycle where by bacteria attached to a surface irreversibly and start to produce the EPS. This forms a colony known as a microcolony, which futher grows to form a macro-colony. This colony further develops and bacteria start to adapt to specific roles (or niches) based on where they are in the biofilm, this is known as maturation. Once the biofilm matures, bacteria can be released into the environment as free floating cells to start the biofilm forming process all over again in an event known as dispersal.



Attach, grow and disperse- The biofilm life cycle made easy3


In this blog series, I hope to convey the highlights of biofilm biology and technology. I will explore areas such as biocorrosion, biofilms in public health and the environment and my favourite area- Biofilm Electrochemistry! Next week we will see how bacteria communicate to form the biofilm!









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