The Glucose Metabolism Variation of Clostridium butyricum during Domestication with Different Anode Potentials

Abstract:

Clostridium butyricum was used as a type strain for studying its glucose metabolism and bioelectrical activity with different anode potentials (+0.6, +0.2 and -0.2 V, vs Ag/AgCl). When using 1 mM glucose as substrate and connecting 1000 Ωresistance, the output voltage of the microbial fuel cell was about 0.09 V, which proved a good bioelectrical activity of the strain. During the domestication of the strain with three anode potentials, the bioelectrical activities and glucose metabolisms of the three groups were quite different. The maximum output current of group 0.6 and 0.2 V were ca. 1.8 and 1.2 mA, while the group -0.2 was only ca. 0.02 mA at the end of domestication. While the OD600 of group -0.2 was 0.3 which was much higher than the other two groups (ca. 0.01). The end products of glucose metabolism in different groups and domestication cycles were different. At the beginning of the domestication, the end productions were similar. Succinate, lactate, ethanol, acetate and hydrogen were the main end productions, which suggested the metabolism type of three groups was fermentation. At the end of domestication, the content of succinate, lactate, ethanol and hydrogen of group 0.6 and 0.2 were decreased, carbon dioxide increased. While a large sum of butyrate generated in group-0.2. In addition, the content of carbon dioxide in this group was much less than group0.6 and 0.2. The glucose metabolism analysis showed a transformation of metabolism from fermentation to anode-respiration with the increasement of the strain C. butyricum bioelectrical activity. The results provided a new perception into the influence of anode potential on the bioelectrochemical systems.