Structurally diverse natural products that cause potassium leakage trigger multicellularity in Bacillus subtilis Article Review

Biofilm formation of bacterial cells, or the ability of bacteria to aggregate in response to certain signaling factors, is a relatively new concept that gives researchers and other scientists an extra load of scientific works. These works are connected to the idea that scientific investigators find it hard to establish facts that will clearly describe the event by which bacterial species, which were traditionally regarded to be solitary in nature, will begin to form communities. Myxobacteria, streptomyces and other groups of bacteria with clinical or industrial importance have been found to form biofilms under special conditions (Lopez et al., 2009). To further investigate this issue, the researchers studied Bacillus subtilis under varying nutritional and cultural conditions. They decided to grow B. subtilis on MSgg and LB and it was discovered that B. subtilis which were grown in minimal defined medium MSgg allowed biofilm formation while cells of the same species that were grown in complex medium of LB showed no biofilm formation. Hence, researchers speculated that there might be a specific factor that is present in  MSgg which has triggered the bacterial cells to aggregate.

In order to investigate this event, the researchers exposed B. subtilis cells to a battery of compounds including polyene polyketide nystatin and filipin, and other non-specific membrane disrupting detergents (Lopez et al., 2009). Among these compounds, only nystatin was found to induce biofilm formation of B. subtilis after it was supplied to LB. The inability of the other compounds to induce biofilm formation in B. subtilis suggests that the cation leakage from the cytoplasm to the extracellular space caused by nystatin is the primary element that signals bacterial cell aggregation. The previously mentioned statement is the hypothesis of this study which was tested by subjecting the microorganism to a list of naturally occurring small molecules. More specifically, B. subtilis was exposed to amphotericin, gramicidin, surfactin, and iturin (Lopez et al., 2009). Both amphotericin and gramicidin are capable of causing cation leakage but only amphotericin has similar structural configuration with nystatin. Surfactin and iturin, on the other hand, are cyclic lipopeptides which are produced by different strains of B. subtilis. Results showed that amphotericin, gramicidin, and surfactin stimulated the production of biofilm, an event which suggests that potassium cation leakage might be the cause of the biofilm signalization. Other compounds exhibiting no cationic leakage were eventually included in the experiment for comparison purposes and it was found out that they were not capable of inducing biofilm formation.

Next, researchers decided to expand investigations on the property of nystatin and surfactin because these two elements pose intriguing concerns for the investigators., The property of surfactin of being a natural by-product of B. subtilis and the non-surfactant nature of nystatin heightened the interest of the researchers. They discovered that these two compounds activate the regulatory circuitry that controls matrix production and protein kinase C (Lopez et al., 2009). Consequently, these events lead to the lowered intracellular potassium concentration in B. subtilis and to biofilm formation. In general, it can be observed that the results are consistent with the original hypothesis.

I actually picked this article because I am really interested with biofilm formation. I find it really amusing to know that the very small microorganisms are able to physically manifest themselves to us by forming slimy biofilm formations on the surface of plastic wares or metal utensils. Furthermore, this article was chosen because I believe that it will help me gain increased understanding of the processes of microorganisms.


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