Article notes - Microbial Biofilms Flashcards
What is a biofilm? What organisms may it contain? Is there anything else in them?
A biofilm is a culture or community of microbes that have attached themselves to
the surface. These microbes can be singular kind or multiple types which is more
common natural environments
what are examples of biofilm?
Some of these biofilms live within us like the plaque on our teeth or in our gut.
Some in bottles of liquids like apple juice or kombucha or fungal biofilm found in
the shower.
Why are these important to us and to microbes? How do biofilms benefit microbes?
Biofilms are important to us as they help keep important microbes that are
necessary for humans safe and within our system. Biofilms benefit microbes as
they are composed of cells and an extracellular matrix which helps keep the
biofilm community stable and releases proteins and polysaccharides to the
microbes within the community. It also blocks out viruses and microbes that can dry out the community
In what environments have biofilms been observed? And what is their role or significance each of these locations?
Biofilms have been observed in environments where nutrients are scarce as this
causes a more concentrate in nutrients. They can be found in wastewater treatment
plants, fermented food, they protect plants from pathogen attacks and can help aid
in biofuels making, these are the benefits they have, although they are also
associated with infections within the human body like on pacemakers and
catheters
describe the three broad approaches used to study biofilms and the advantage of each
The first broad approach to studying biofilms is using direct sampling/visualization of the biofilms which includes variety of stains paired with
differing microscopy like bright field/phase, scanning/transmission or fluorescent. These approaches provide morphological data, like the shape and organization of
the microbes. The second approach is to use flow devices that mimic the
environment of the biofilms, and this allows the scientist to control for everything
like the environment conditions, microbes growing and the time. The third
approach is to use plastic dishes which allows for the analysis of biofilm earliest
formation, which allows for the ability to observe genetic variants and strains of
the biofilm
where would you expect to
see a biofilm form if you are growing a strict aerobe, as compared to an organism that may live anaerobically?
According to figure 4 if a biofilm is aerobic, then it will form at the surface-air
interface because it needs oxygen to grow and form, while an organism that is
anaerobically, it will coat the entire wall as it does not require oxygen to form or
grow. An example of this would be the mat found at the top of kombucha as it
forms biofilm between the liquid and air interface.
what is the cycle of biofilm formation/breakdown
- reversible attachment
- irreversible attachment
- microbes grow
- matrix formation
- dispersal
how is surface sensing related to biofilm formation?
Surface-sensing is the detection of a surface to start the formation of biofilm. They use two different structures, the flagella and pili. The flagella is known as microbial propellers, it helps the bacteria move and swim through liquid, but when it is stuck to the surface it will rotate the cell rather than swimming. The pili are known for adhesion and stick to a host or other bacteria, but when it sticks to a surface it makes it difficult to
retract so it sends signals that triggers a plethora of changes for the bacteria to change its lifestyle to adapt to the surface
How is the lap system related to biofilm formation?
Lap system includes multiple parts to it, but it is used for irreversible attachment in larger cells, and it contains protein LapA. LapA is made in the cytoplasm, and it secreted through the pores of the inner and outer membrane, although LapA is blocked and retained in the outer membrane by the N-terminal domain that folds and blocks the LapA secretion. This is when LapA tethers to the cell and makes biofilm and it will remain if the surrounding conditions are good, and the cell make high levels of cyclic-di-GMP. Cyclic-di-GMP is bound to an inner membrane receptor, LapD and it goes through a
change, LapD binds to LapG and LapG is then taken away from the target in the N-
terminal site. Although when cyclic-di-GMP levels drop, LapD goes to an unbound
conformation and LapG is released and cleaves off the LapA N-terminal domain. Then LapA is released from the cell and the bacteria cannot attach to the surface anymore, which will affect the biofilm adhesion
