2.9 Biomass determination and Viability counts The culture broth was collected for the determination of cell turbidity. It was subjected to spectrophotometer at the wavelength of 600 nm. The fresh culture medium was used as blank. Then, the viability counts were performed by serial dilution in fresh medium. The media used for plate counts were MRS and DifcoTM Reinforced Clostridial media for L. acidophilus BCC 13839 and B. animalis ATCC 25527, respectively. They were incubated at 37 oC for 24-48 h and the colony forming unit was calculated by multiplying with the dilution rate. The petri-dish with 30-300 colonies was determined.