Bacillus Subtilis: Infection, Transmission & Diseases

Bacillus subtilis is a single-celled organism that occurs in nature primarily in the top layer of the earth. Pharmaceutical use of Bacillus subtilis includes antibiotics, for example, to treat gonorrhea.

What is bacillus subtilis?

Bacillus subtilis is also known as hay bacillus. Christian Gottfried Ehrenberg described the protozoan as early as 1835. The bacterium is rod-shaped and moves around with the help of a flagellum. The unicellular organism moves the thread-like flagellum like a propeller for locomotion. Bacillus subtilis is an aerobic bacterium: its metabolism requires oxygen. Today, biology recognizes three subspecies with different characteristics. In addition, Bacillus subtilis belongs to the endospore species. An endospore is a capsule form in which a bacterium can survive unfavorable living conditions. The spore is formed within the protozoa. In Bacillus subtilis, lack of food triggers the formation of the endospore. The bacterium is heterotrophic and must take up nutrients produced by other organisms. The decreasing availability of guanine serves as an indicator of food shortage. The lack of guanine triggers a biochemical reaction in the bacterium. The cell wall divides within the bacterium and forms a bubble in the cell body. Encapsulated within this, the protozoa can survive unfavorable environmental conditions. Spores are particularly resistant to cold, heat, acidic or alkaline conditions, drought, and radiation. When living conditions become more favorable for the Bacillus subtilis again, the spore activates and, during subsequent germination, metabolism gradually resumes. Finally, the Bacillus subtilis outgrows its protective shell and can now move and reproduce undisturbed again.

Occurrence, distribution, and characteristics

The natural habitat of Bacillus subtilis is the top layer of soil. However, the bacterium is also found in the air or water. It finds particularly good growing conditions in compost soil. In autumn, when the leaves fall and provide Bacillus subtilis with many nutrients, the bacterium emerges in particularly high numbers. As an endospore-forming species, Bacillus subtilis can survive prolonged periods of starvation and drought by retreating into a capsule. The bacterium can reproduce best at 40 °C. At this temperature and with an adequate supply of oxygen, it divides once every 26 minutes. For its nutrition, Bacillus subtilis depends on other living organisms that are found in the soil. That is why it is not only found in the top layer of soil, where it can find a particularly large amount of nutrients. Bacillus subtilis also feels at home in the immediate vicinity of living roots – in the rhizosphere. It prefers glucose (dextrose), which plants produce by photosynthesis, as its main food. Bacillus subtilis also breaks down starch, which consists of long chains with many sugar molecules. In this broken form, the micro-organism can process the glucose.

Importance and function

Bacillus subtilis is not found in the human body in principle and thus has only an indirect effect on health. The single-celled organism is completely harmless. Unlike other bacteria, Bacillus subtilis does not cause disease, but can even help fight bacterial infections. However, not all strains of Bacillus subtilis can synthesize antibiotics. Bacillus subtilis is contained, for example, in bacitracin (more rarely: bazitrazine), which physicians used as an antibiotic as early as 1945. The mechanism of action of this drug is based on the fact that Bacillus subtilis inhibits the growth of other bacteria that are potentially harmful. In doing so, Bacillus subtilis interferes with the synthesis of cell walls. The cell wall of the stabilizes and protects the cells of plants, fungi and some protozoa. The body cells of humans, on the other hand, do not have a cell wall, as they belong to the animal cells. Accordingly, the inhibitory effect of Bacillus subtilis on cell wall synthesis has no significance for human cells.

Diseases and ailments

The antibiotic bacitracin, which contains spores of Bacillus subtilis, is effective against Gram-positive bacteria, which owe their name to their reaction to a particular dye. In addition, Bacillus subtilis fights gonococci (Neisseria gonorrhoeae).These are bacteria that can lead to various infectious diseases in humans. The most common of these is gonorrhea. This sexually transmitted disease is also popularly known as gonorrhea and occurs frequently. Worldwide, about 1% of the population contracts gonorrhea. Infection with gonococci often does not cause symptoms in women. However, when the infection visibly manifests, discharge and pain on urination are among the characteristic signs. In addition, in some cases the urethra secretes purulent secretions. In women, if the gonococci spread further inside the body via the ureter, adnexitis may occur. This is an inflammation of the appendages (adnexa). As a rule, the fallopian tubes and ovaries are affected. In extreme cases, this can result in infertility. Furthermore, there is a risk of abortion if the amniotic sac is also affected by the inflammation. In men, gonorrhea manifests itself in an inflammation of the mucous membrane of the urethra (urethritis), which secretes pus and causes pain. In men, the infection can also rise, possibly leading to inflammation of the prostate (prostatitis) or inflammation of the epididymis (epididymitis). This also carries the risk of becoming infertile.