Pickles are often preserved in a 20-30% salt solution called brine. how does this method prevent contamination by microorganisms?

The salt solution (brine) is a  hypertonic solution. It means that there is a higher concentration of dissolved salts outside of the cell, and a lower concentration of water than the cell. If the concentration difference is too great, the microorganisms  cannot survive because the cells  will be  dehydrated and soon die, 

links? do you have a link? i don't see anything?