초록
Both static and agitated culture methods have their own disadvantages on producing bacterial cellulose (BC). To reveal the metabolic differences between these two culture methods, the intracellular metabolic profile characterization of Gluconacetobacter xylinus was investigated using gas chromatography coupled with mass spectrometry. A total of 79 intracellular metabolites in G. xylinus were detected and quantified. Trehalose was mainly responsible for the discrimination among different cultural groups. Coupled with metabolic network, BC production was divided into two stages in agitated culture. At the first stage, glucose was more converted to gluconic acid at high rotational speeds, resulting in a low conversion rate of glucose to BC. At the second stage, gluconic acid acted as carbon source pool for BC synthesis under glucose-limited conditions. However, the accumulation of self-protection metabolites (trehalose, amino acids and gluconic acid) on the 2nd day at 280rpm branches much carbon source from BC synthesis, resulting in the inhibition of BC synthesis. The highest conversion rate of glucose to BC was observed in static culture, attributing to the inhibition of Glucose-6-phosphate dehydrogenase and the accumulation of by-products. These might be the possible reasons that G. xylinus in static and agitated cultures gave distinct BC yields.