Why Is Bacillus Often Resistant to Disinfectants?

Bacillus often show resistance to harsh environments such as heat, radiation, disinfectants and drying due to their endospores. According to MicrobiologyBytes, spores of Bacillus have a tough outer covering made of keratin, making them highly resistant to heat and chemicals.

According to Cornell University's Department of Microbiology, the endospores of Bacillus give the organism the ability to thrive and grow in difficult environments such as deserts, hot springs, Arctic soils and marine sediments. Endospores are a dormant form of the bacterium and only a few genera of bacteria, such as Bacillus and Clostridium, are capable of forming endospores. Bacillus is found in the soil, while Clostridium can be found in the gastrointestinal tract of animals.

Endospores form under conditions of starvation. Cornell explains that a single endospore forms within a bacterium by a process called sporulation, which requires a great deal of time and energy from the bacterium. Once formed, multiple layers of resistant coats, such as a cortex, spore coat, and at times an exosporium, cover the completed endospore. Until a variety of environmental triggers encourage germination, the endospore survives and bides its time. Once encouraged to grow, an outgrowth of a single bacterium is produced from germination. The endospores of Bacillus are a highly effective adaptation in survival.