Batch acidogenesis was performed at xA
Batch acidogenesis was performed at 37 °C and at pH 8 as the optimum conditions. Culture immobilization on kissiris increased the OAs yield in most of the tested sucrose/raffinose mixtures as compared with free cells. The highest improvement was observed in the case of 100% raffinose and the 30% sucrose–70% raffinose mixture. Table 1 shows the results of the batch acidogenesis of sucrose and raffinose mixtures with and without the use of kissiris. Bioconversion of sucrose and raffinose occurred in all fermentation batches indicating the capability of the mixed ABT-737 culture to ferment this type of sugars. The OAs yield factor varied from 0.38 to 0.62 g/g for an initial sugar concentration of 20 g/L. OAs concentration ranged from 5.9 to 13.4 g/L, while ethanol formation did not exceed 0.5 mL/L. Without kissiris the OAs concentrations and yield factors were lower, while higher concentrations of ethanol were observed. OAs that were formed were lactic, valeric, acetic, propionic, succinic, and butyric acids, and in few cases isovaleric acid. Lactic acid and valeric acid were the predominant acids in most cases. These results encouraged the subsequent study of continuous acidogenesis using immobilized cells in order to achieve the aforementioned objectives.