摘要
This research focused using novel substrate, longan Lactobacillus casei subsp, rhamnosus TISTR 108. The optimum juice as carbon source for continuous lactic acid production by medium for lactic acid production was pure longan juice with 120 g/L sugar concentration and among the different nitrogen sources were added to the longan juice （yeast extract, tryptic soy, urea, （NH4）2SO4 and NaNO3）, yeast extract had the most efficiency. Yeast extract （10 g/L） without adding minerals to longan juice could produced the maximum lactic acid concentration of 38.91 ± 0.190 g/L in 60 h and the yield of 0.460± 0.122 g/g with the productivity of 0.649± 0.002 g/Lh in 2 liters flask. Batch fermentation was conducted in 2 liters fermentor and 41.38± 0.030 g/L lactic acid was produced in 48 h with the yield of 0.398 ± 0.215 g/g and the productivity was 0.862 ± 0.001 g/L h. The continuous fermentation using 2 liters fermentor as a high productivity for lactic acid （1.091 ± 0.001 g/L h） was achieved at dilution rate （D） of 0.0685 h-1.
