Samples were collected at appropriate intervals for measurement of cell, glycerol and citric acid concentration. For quantification of cell concentration, optical density of cultures was measured at 600 nm and converted to dry cell mass per liter by a calibration curve. Glycerol concentration was quantified by high-performance liquid chromatography (HPLC) using a Metacarb 87H column (300 mm × 7.7 mm) coupled to a RI detector. The eluent was H2SO45 mM at 0.5 mL min−1 and the column temperature was 60◦C, maintained with a column thermostat. Citric acid concentration was measured by HPLC using aYMC ODS-Aq (250 × 4.6 mm)reverse phase column coupled to an UV detector at 214 nm. The mobile phase was KH2PO420 mM, pH 2.8 at room temperature and a flow rate of 0.7 mL min−1