The effect of initial glucose concentration (varying between 50 and 150 g/L) had been investigated. The fermentation efficiency of lactic acid at different initial glucose concentration showed that the maximum fermentation efficiency was observed at 50 g/L for free cells and 75 g/L for ISi-L. rhamnosus. An identical pattern of inhibition was observed for free L. rhamnosus. Furthermore, the fermentation efficiency of ISi-L. rhamnosus was relatively higher than that of free cells at glucose concentrations of 75 g/L – 150 g/L (Fig. 4A). The production of lactic acid at high initial glucose concentration was desirable because it would attribute to be a result of increasing the accumulation of lactic acid concentration and reducing downstream processing costs (32).