The fermentation broth was centrifuged at 20,000 x g for 10 min, the supernatant was collected, and lactic acid and residual glucose concentrations were assessed using an HPLC apparatus equipped with a refractive index detector (Agilent, USA). The utilized column was an Aminex HPX-87H (Bio-Rad Co., USA), and chromatography was performed at 40°C using 0.01 N H2SO4 as the eluent at a flow rate of 0.6 ml/min