To investigate the effect of pH on organic acid production by Anaerobiospirillum succiniciproducens, an anaerobic fermentation was carried out by maintaining the pH of the fermentation broth at 5.8, 6.0, 6.4, 6.8, and 7.2. At various pHs, the concentrations of cell were 1.0^-1.9g/P which were two to three times higher than those of the other worker´s results, and the maximum was obtained at pH 5.8. Substrate consumption was increased by increasing the pH in the range of pH 6.0 to 6.8, while the sugar consumption rate at both pH 5.8 and 7.2 was very slow. The total amount of 2M Na2CO3 added for adjustment of pH change due to organic acid production was maximum at pH 6.8. Changes of conductivity of the fermentation broth was very similiar to those of 2M Na2C0, added at various pHs. Therefore, it is suggested that determination of the amount of organic acid in a broth can be possible by measuring the conductivity. The maximum production yield of lactate based on glucose was 64% for pH 7.
2 and 32% for pH 6.8, respectively.
|