Fermentation of sugarcane molasses
Results of KO11 and P2 fermentation of molasses diluted 10-fold in distilled water and in vinasse are presented in Fig. 6A and 6B, respectively. E. coli KO11 molasses fermentation diluted in water or in vinasse resulted in low ethanol yields. Suplementation of molasses did not result in an increase in ethanol production by KO11, that produced only 18.1 g ethanol/L whithout suplementation and about 15.5 g/L with yeast extract or LB reagents. In molasses diluted in vinasse, KO11 produced 14.4 g ethanol/L without supplements and about 16.6 g/L with yeast extract or with LB components. There was a relatively KOH consumption during fermentation to maintain pH. Acid analysis by HPLC indicated high lactic acid concentration in the fermentation medium (results not shown), indicating a possible loss of ethanologenicity by KO11.
In contrast to KO11, K. oxytoca P2 fermented molasses efficiently. In molasses diluted in water, ethanol production after 96h was 25.6 g/L (no supplements), 24.6 g/L (with yeast extract) and 27.8 g/L (with LB). In molasses diluted in vinasse, ethanol production was 24.4 g/L (no supplements), 24.6 g/L (with yeast extract) and 25.1 g/L (with LB). Addition of yeast extract or LB promoted rapid P2 fermentation that reached a maximum ethanol yield within 24h and stabilized after this time probably because of sugar depletion in the medium.
Fermentation of sugarcane molassesResults of KO11 and P2 fermentation of molasses diluted 10-fold in distilled water and in vinasse are presented in Fig. 6A and 6B, respectively. E. coli KO11 molasses fermentation diluted in water or in vinasse resulted in low ethanol yields. Suplementation of molasses did not result in an increase in ethanol production by KO11, that produced only 18.1 g ethanol/L whithout suplementation and about 15.5 g/L with yeast extract or LB reagents. In molasses diluted in vinasse, KO11 produced 14.4 g ethanol/L without supplements and about 16.6 g/L with yeast extract or with LB components. There was a relatively KOH consumption during fermentation to maintain pH. Acid analysis by HPLC indicated high lactic acid concentration in the fermentation medium (results not shown), indicating a possible loss of ethanologenicity by KO11.In contrast to KO11, K. oxytoca P2 fermented molasses efficiently. In molasses diluted in water, ethanol production after 96h was 25.6 g/L (no supplements), 24.6 g/L (with yeast extract) and 27.8 g/L (with LB). In molasses diluted in vinasse, ethanol production was 24.4 g/L (no supplements), 24.6 g/L (with yeast extract) and 25.1 g/L (with LB). Addition of yeast extract or LB promoted rapid P2 fermentation that reached a maximum ethanol yield within 24h and stabilized after this time probably because of sugar depletion in the medium.
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