Growth curves were determined by inoculating approximately1 g fresh weight of suspension cells filtered using sterile GFC fil-ters in 250-ml Erlenmeyer flasks containing 50 ml of medium. Cellswere harvested every 3 days to determine the pH and optical den-sity. The absorbance of the suspension culture was recorded using aUV–spectrophotometer (UV-2450, Shimadzu) to determine abso-lute cell growth.