Increased osmotic pressure has been used to control the growth of food spoilage and pathogenic bacteria by dition of high amounts of osmotically active compounds, which resulted in decreased water activity. Under normal conditions, bacterial cells maintain turgor pressure, which is a higher internal osmotic pressure than that of the surrounding medium. As a result, pressure was exerted outwards on the cell wall and this turgor pressure was the mechanical force for cell elongation (Csonka 1989).