Why does salt have antibacterial properties?
Feeling salty? Due to its antibacterial properties salt has long been used as a preservative.
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:
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
