Fundamentals of Microbiology

2.2.3 Radiation

Many forms of electromagnetic radiation are harmful to microorganisms. As the wave length of the electromagnetic radiation decreases, the energy of the radiation increases. Gamma rays and x-rays are more energetic than visible light or infra-red waves.

Radiation is the emission and propagation of energy through a space or material medium.

Radiation can be of two types:

1. Ionising radiation

2. Non ionising radiation

Ionising radiations can cause atoms to lose electrons or ionize, so called ionising radiation. Two major forms are 1) X-rays, which are artificially produced and 2) γ (gamma) rays – which are emitted during radioisotope decay. Low levels of ionising radiation produce mutations and indirectly result in death, whereas higher levels are directly lethal. Destruction of DNA is the most important cause of death of organisms. There are some bacteria, for example Deinococcus radiodurans can survive large doses of ionising radiation.