by Laura Domicevica
As my first blog post for the Homo biomedicus, I wanted to start with something small. Microscopic, actually. They can talk, sense, warn others of their kin about danger and even cooperate for greater purpose. And yet we cannot see them with a naked eye. World of bacteria is wrongly accused of being dull and simplistic with nothing of interest to offer. However, among many surprising features that we already know of another one has emerged.
Most bacteria have a cell wall that shields them from outer world and allows them to keep a characteristic form and interact with environment. It is also their weak point, exploited by our immune system and antibiotics such as penicillin. Surprisingly, evidence has been found that these organisms can lose their cell wall and transform into L-forms. Such bacteria are often associated with chronic infections, with the most recognizable members from genus Mycoplasma which are often found in pneumonia patients. These bacteria are not recognised by our immune system and cannot be destroyed by most antibiotics used in traditional therapy. Antibiotic resistance is a widespread problem in healthcare. For example, the epidemics of MRSA (Methicillin resistant staphylococcus aureus) in hospitals around the world.
Researchers in Centre for Bacterial Cell Biology were able to make a Bacillus subtilis strain that could be induced to rapidly lose its cell wall and become a stable L-form and back. This is a great success and an extremely useful tool for L-form research. Although we know that cell wall can be lost naturally, it is a difficult process to repeat in a laboratory environment and even after decades of research, the changes that drive this conversion are mysteries to the microbiologists. L-form cells are fragile and sensitive to osmosis, as there is no cell wall that could guard them from the influx and efflux of metabolites – salts and nutrients.
With the modifiable strain at their disposal, insight of the manner of L-form emergence could be obtained. It soon became apparent that the protoplast, i.e. the inner parts of a cell, including cell membrane, emerges from a bulge in cell membrane and eventually separates as L-form, leaving now empty cell wall behind. This process can also happen at the sites of cell division.
Researchers predict that their method could be used to make similar strains and eventually underpin the molecular mechanisms in organisms like staphylococci and streptococci – well known human disease-causing agents. Deeper insight in the formation of L-forms might lead to new designs for antibiotics and novel therapies.
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