"Bactericides kill bacteria". What is the meaning of "killing" in this context, and how exactly is this "killing" happening chemically?
Each bactericidal agent has a different mechanism of action. For example:
- Alcohol denatures proteins necessary for function and the lipids in the plasma membrane dissolve into the alcohol.
- "Iodine can penetrate the cell wall of micro-organisms quickly, and the lethal effects are believed to result from disruption of protein and nucleic acid structure and synthesis." [CDC]
- other mechanisms include tampering cell metabolics, tampering DNA replication, and more.
- The 2008 CDC guidelines for sterilization and the such for healthcare settings. Each method will contain a comprehensive description along with a statement of "mode of action," i.e. how the method actually kills the bacterium.
- Another good link here from the CDC examines factors affecting the efficacy of sterilization.
Otherwise, it would be best therein to split the specific mechanisms you perhaps don't understand into separate questions. But an important take-home message in the efficacy link above just adds to just how broad this question is:
Microorganisms vary greatly in their resistance to chemical germicides and sterilization processes.