The Subtle Beauty of Bacillus Subtilis (Part III)
Natto is not the first product made by Bacillus subtilis to provide benefit to human health. This bacteria is also the source of one of our oldest and widely used antibiotics, bacitracin.
An interesting story: The name of the antibiotic "bacitracin" is derived from a combination of (a) its biological source (Bacillus subtilis) and (b) the person in whom it was found (M. Tracy).
This useful drug was first discovered and isolated from a hospital culture derived from an abscessing leg wound of a young girl named Margaret Tracy back in the 1940's. In trying to diagnose and treat her infected leg, doctors realized that one component from the wound had a strong protective, antibiotic effect---this turned out to be coming from Bacillus subtilis that was present in the wound. When doctors and scientists looked further, they found this antibiotic activity was due to a natural chemical bio-product which they then named bacitracin.
Here is the original scientific article on bacitracin's discovery from 1945 (3)!
References: (1) Dougherty, T. (2012) Antibiotic Discovery and Development: Volume I. Springer Publishing. (2) Wikipedia {bacitracin]: https://en.wikipedia.org/wiki/Bacitracin (3) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC518064/pdf/jbacter00667-0106.pdf (4) Jonathan Dworkin, PhD. personal communication.
Bacitracin is one of the most common antibiotics in first aid over-the-counter topical antibiotic cremes, antibiotic-containing bandages, and opthalmic antibiotic ointments (to treat pink eye).
Bacitracin is a natural antibiotic molecule produced only by Bacillus subtilis bacteria. Most of our best antibiotic drugs are, in fact, substances made by microorganisms as a defense mechanism to protect themselves from other threatening species of microbes. Bacitracin works by interfering with synthesis of the essential protective cell wall, thus crippling many other (than itself) bacterial species (1, 4).
Demonstrating antibiotic activity. A petri dish culture of bacteria (brown haze) growing on agar media topped with small white discs which are filter papers impregnated with samples of other bacterial species or purified small molecule products. Antibiotic activity is shown by the appearance of a "halo" of no bacterial growth around the source of "killing activity". The size/diameter of the "zone of death" indicates strength of activity.