Production of Bacterial Cellulose by Acetobacter Xylinum: Effects of Carbon/nitrogen-ratio on Cell Growth and Metabolite Production

The effects of carbon/nitrogen ratios on production of bacterial cellulose (BC), by submerged cultivation of Acetobacter xylinum NUST4.2, were investigated using central composite design and response surface analysis. The accumulation of metabolite was linked to cell growth. Amongst organic sources, peptone was favorable for BC production, while glucose was observed as the best carbon source. The C/N-ratio of 5.39 encouraged the proliferation of bacteria. Data demonstrated that a low C/N-ratio resulted low production of the target product, and 30.01% of the carbon source was used to produce the by-product of gluconic acid, and only 12.36% was used in the BC production. When the initial C/N-ratio was adjusted to 6.31, the metabolic flux analysis showed that 20.96% of glucose fluxed into bacterial cellulose. The C/N-ratio was optimized and improved BC production was accomplished by shifting the metabolic distribution. Under the optimized conditions, the maximum production (1.57 g/l) of bacterial cellulose was obtained in a 15-liter fermentator, which was by 45% higher than that obtained before.