As shown in Fig.3B, the concentration of glucose increased in the beginning and then decreased in the three fermentations. The final concentration of glucose in the co-culture fermentation was significantly (p < 0.05) higher than that in L.p1121 fermentation.
Therefore, taking into account that the number of viable cells in L.p1121 fermentation was higher (p < 0.05) than that in the coculture fermentation while the L.p1121 dominated the fermentation,these results suggested that the utilization of glucose by
L.p1121 was not stimulated in the co-culture fermentation. However,it was found computationally that the decrease of glucose by an L.p1121 cell was higher in the co-culture fermentation(1.91 106 g) than in the starter fermentation (1.67 107 g) after
60 h fermentation when the L.eu1426 can not be detected. The better utilization of glucose by an L.p1121 cell in the co-culture fermentation may benefit from the low concentration of sucrose.
There was no decrease in the concentration of fructose in L.eu1426 and the co-culture fermentation. The final concentration of fructose in the co-culture fermentation was significantly(p < 0.05) lower than in L.eu1426 fermentation. This difference may
result from the existence of L.p1121 which can utilize the fructose distinctly.