Final answer:
UV light limits microbial growth by causing damage to microbial DNA through the formation of thymine dimers and generating reactive oxygen species. It's used in various disinfection applications but has limitations due to its poor penetrating ability. Other methods like ionizing radiation may be used for applications requiring deeper penetration, such as food treatment.
Step-by-step explanation:
UV light can limit microbial growth through several mechanisms. One of the most significant effects of UV light, specifically UV-B and UV-C, is the formation of thymine dimers within the DNA of microorganisms. This damages the DNA and inhibits proper replication, leading to mutations and potentially causing the microorganisms to die. UV light has the energy required to alter molecules, unlike visible light.
In addition to the direct DNA damage, UV light can interact with oxygen to produce reactive oxygen species that can also damage cellular components. For disinfection, UV lamps emitting UV light at a wavelength of 260 nm are used in various settings, including water purification systems, surgical suites, and biological safety cabinets.
UV light does have its limitations, as it is not very penetrating and does not pass through plastic or glass. Consequently, for it to be effective, cells must be directly exposed to the UV source. In terms of treating food, other methods like ionizing radiation can be used, as UV light's poor penetration makes it less than ideal for this application.