Microorganisms are everywhere. Run your tongue over your teeth: that fuzzy feeling after a meal is a microbial community laying down foundations on your enamel. These communities, or biofilms, can form on almost any surface, especially if the surface is slightly wetted. That includes river rocks, the inside of your tap and even the lining of your gut. “Don’t panic!” (I had to remind myself during the first part of my research). For the most part microorganisms perform vital functions in ecosystems and our own bodies. We use biofilms in bioremediation plants to treat wastewater and as micro-factories to produce certain biochemicals.
Seeing as we share so much of our planet and intimate internal spaces with microbes it is worthwhile getting to know these critters better. Now, keep in mind that when I started my research, I didn’t know anything about microorganisms. I opted to study psychology instead of microbiology during my undergraduate degree (#ifonlyIknewthenwhatIknownow). So this post is a very basic summary of what I had to learn in the first year of my PhD.
We first discovered microorganisms in their single free-floating, planktonic forms in the 1600s. As microscopic techniques advanced over the years our understanding of this parallel miniscule universe has greatly improved. We now know that almost all microbes have the ability to attach to a surface and that most of them prefer living together in these anchored communities. Biofilms are made up of three parts: the organisms themselves, the slime they produce and the water molecules trapped between the slime particles.
Benefits of being in a biofilm
Biofilms have been called microbial cities: microorganisms build three-dimensional slime structures, live in close quarters and share resources. There is strength in numbers: together they create a favourable environment, this self-created matrix structure anchors them to a surface while protecting them from predators and harmful chemicals. Like our cities space, waste and food can create tension between neighbours but it means the community stays fighting-fit.
In laboratories we tend to study single-species biofilms – they’re easier to cultivate and it’s easier to draw conclusions when you are studying a homogeneous population. The truth is that single-species biofilms hardly ever occur in the natural world. Biofilm communities can include many different kinds of bacteria and eukaryotic species (organisms that have cell centres and membrane-enclosed organelles). Scientists are only starting to grasp the incredible complex communication methods that develop within these communities, something like chemical Twitter. The ability to communicate is vital to the survival of these microbial communities and often underpins their ability to dodge our anti-microbial treatments.
Most of us have an instinctive “ewh gross” response to the thought of microorganisms and use anti-microbial chemicals on the daily. Read the contents of your dishwashing liquid, toothpaste or shampoo: almost all personal care products contain chemicals like triclosan, triclocarban or alcohols. Most of these are completely unnecessary: we need certain bacteria on our skin to maintain a healthy pH and our digestive system is dependent on microflora in our gut. Watch Rob Knight explain the wonder that is your personal microbial community:
Of course some microbes can make us sick. Pseudomonas aeruginosa is one of the most common culprits, an opportunistic pathogen that is a leading cause in many hospital-acquired infections and chronic lung infections. P. aeruginosa has inherent abilities to resist many antibiotics, especially in biofilm-form, and is one of the ‘superbugs’ we struggle to combat with drugs. Because microorganisms are constantly exposed to sub-lethal levels of anti-microbial chemicals (the soaps etc. we flush down our drains) they have the opportunity to develop coping mechanisms. When resistance mechanisms develop in a microbe it can pass these lessons along to others in the biofilm community. That’s why biofilms in food processing plants, water distribution systems and hospitals pose such a threat to us; they can harbour drug-resistant terrorists.
Another reason to “go green”: I’m in the process of replacing all my household cleaning and skincare products to natural alternatives. You can find great locally-produced ones online; I recommend Earthsap and Bee Natural!
The self-produced ‘slime’ matrix that houses the community is the key to its ability to adapt, evolve and survive. Microorganisms form this matrix by secreting a wide range of macromolecules (proteins, carbohydrates, lipids and even DNA): each biochemical component has its own function and provides additional functions in combination with other components. In a natural environment there are infinite combinations of microbes that may form a biofilm community, these communities can produce infinite combinations of biochemical matrixes, the composition of the community and matrix changes over time and adapts to changes in the environment, creating infinitely complicated systems.
Infinitely complicated systems… sounds like a create topic for a PhD, right?