 Mechanosensitive channels are major pathways for the release of cytoplasmic solutes to achieve a rapid reduction of the turgor pressure, therefore avoiding lysis.Gene disruption experiments confirmed that either MscL or MscS channels can rescue bacteria from a strong osmotic shock, while a double knockout of both channels lead to lysis.The role of MscL as a defense mechanism against osmotic shocks indicates its evolutionary importance even during the early phase of biological history.