Kornmann H, Duboc P, Niederberger P, Marison I, von Stockar U
Laboratory of Chemical and Biological Engineering, Institute of Chemical Engineering, Swiss Federal Institute of Technology Lausanne, 1015, Lausanne, Switzerland.
Appl Microbiol Biotechnol. 2003 Aug;62(2-3):168-73. doi: 10.1007/s00253-003-1299-2. Epub 2003 Apr 16.
The influence of residual ethanol on metabolism of food grade Gluconacetobacter xylinus I 2281 was investigated during controlled cultivations on 35 g/l glucose and 5 g/l ethanol. Bacterial growth was strongly reduced in the presence of ethanol, which is unusual for acetic acid bacteria. Biomass accumulated only after complete oxidation of ethanol to acetate and carbon dioxide. In contrast, bacterial growth initiated without delay on 35 g/l glucose and 5 g/l acetate. It was found that acetyl CoA was activated by the acetyl coenzyme A synthetase (Acs) pathway in parallel with the phosphotransacetylase (Pta)-acetate kinase (Ack) pathway. The presence of ethanol in the culture medium strongly reduced Pta activity while Acs and Ack remained active. A carbon balance calculation showed that the overall catabolism could be divided into two independent parts: upper glycolysis linked to glucose catabolism and lower glycolysis liked to ethanol catabolism. This calculation showed that the carbon flux through the tricarboxylic cycle is lower on ethanol than on acetate. This corroborated the diminution of carbon flux through the Pta-Ack pathway due to the inhibition of Pta activity on ethanol.
在以35 g/l葡萄糖和5 g/l乙醇为原料的受控培养过程中，研究了残余乙醇对食品级木醋杆菌I 2281代谢的影响。在乙醇存在的情况下，细菌生长显著降低，这对醋酸菌来说并不常见。只有在乙醇完全氧化为乙酸和二氧化碳后，生物量才开始积累。相比之下，在35 g/l葡萄糖和5 g/l乙酸的条件下，细菌生长立即开始。研究发现，乙酰辅酶A通过乙酰辅酶A合成酶（Acs）途径与磷酸转乙酰酶（Pta）-乙酸激酶（Ack）途径同时被激活。培养基中乙醇的存在强烈降低了Pta活性，而Acs和Ack仍然保持活性。碳平衡计算表明，整体分解代谢可分为两个独立部分：与葡萄糖分解代谢相关的上糖酵解和与乙醇分解代谢相关的下糖酵解。该计算表明，通过三羧酸循环的碳通量在乙醇上比在乙酸上更低。这证实了由于乙醇对Pta活性的抑制，通过Pta-Ack途径的碳通量减少。
