Improvement of bacterial cellulose fermentation by metabolic perturbation with mixed carbon sources

Abstract

Bacterial cellulose (BC) has been widely used in many fields because of its nano-structure and excellent biomaterial performance. This work studied fermentation production of bacterial cellulose by Gluconacetobacter xylinus ATCC53524 using mixed carbon sources of glucose and glycerol. The results indicated that with 20 g/L of total carbon source, in medium at the ratio of glucose to glycerol being 1: 3 (w/w), the highest BC titer of 8.42 g/L was reached, which was 1.92 times higher than in conventional medium (20 g/L glucose). Metabolic analysis indicated that 57.1 % of the carbon source was converted into BC in the medium of glucose: glycerol at 1: 3, while it was only 29.6 % in the glucose medium. More ATP was also produced at 1: 3 of glucose: glycerol. The activity of two key enzymes - phosphoglucomutase and UDP-glucose pyrophosphorylase was 1.98-fold and 2.27-fold higher at 1: 3 of glucose: glycerol than those in the glucose medium, respectively. Furthermore, the BC produced in the former case showed higher Young’s modulus, better crystallinity, thicker fibers and lower porosity. The work demonstrated the use of glucose and glycerol at 1: 3 (w/w) was an effective strategy in improving the BC-producing strain’s fermentation performance and BC properties.