Why does salt have antibacterial properties?

Asked by: Dave Cullis, Leicester

Salt kills some types of bacteria, effectively by sucking water out of them. In a process known as osmosis, water passes out of a bacterium so as to balance salt concentrations on each side of its cell membrane. Without water, bacterial proteins such as enzymes cannot function and eventually the cell collapses in on itself.

Some bacteria can tolerate salt; they are halotolerant. Certain strains of Staphylococcus, responsible for infections, blood poisoning, and even death, are halotolerant. These pathogens have a salt alert system that uses sponge-like molecules to prevent water loss.

Read more:

• Do seabirds drink seawater? And if so, how do they prevent salt poisoning?
• Does the body need salt?

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