2.3. Analytical Methods
The samples were centrifuged at 10,000g at 15 ̊C for 20 min. The supernatants were analyzed for concentration of lactic acid [6], starch [7], chemical oxygen demand (COD) [8] and total kjeldahl nitrogen (TKN) [8]. The biomass concentration was determined by drying the cells at 80°C until a constant weight was obtained. Then, the dried cells were weighed. The viable LAB were enumerated by the spread plate technique with the use of MRS agar. DO was measured using a DO meter (YSI 200, YSI Inc., USA).