UV Sensitivity Of Bacteria

Question 1

Why do we use UV radiation (light) to disinfect surfaces/sterilize? What are its limits?

Answer 1

UV irradiation kills organisms indirectly by causing extensive mutation in their DNA.
This happens because the UV light is absorbed by the DNA, causing covalent bonds to form between neighboring pyrimidines bases.
Once these covalent bonds form, DNA can no longer undergo replication correctly. There are repair systems, but these systems often introduce errors which may themselves be lethal, but if not the extended period of UV radiation is lethal itself.
Can NOT penetrate glass/plastic.