Optimization of fermentation conditions for bacterial cellulose production and analysis on cellulose structure

To improve the production of bacterial cellulose,the liquid fermentation conditions of cellulose-producing strain Gluconacetobacter xylinus Gyll were optimized by single factor test,including nitrogen,carbon source,initial pH,seed age,inoculum and static fermentation period.The micro-structure of the cellulose produced by G.xylinus Gyll was observed.The results showed that the optimal fermentation conditions were: sucrose 5%,corn syrup powder 5%,the initial pH of medium 6.2 and inoculum 10%.When the three-step strategy combining static and dynamic fermentation was used,the age of the first stage seed was 24 h,the age of the second stage seed for culture enlargement was 20 h,and the static culture period was 8 days.The highest yield of bacterial cellulose was 11.49 g/L,which was 5 times of the yield before optimization.The fermentation products were identified as cellulose I on the basis of Fourier transform-infrared spectrum(FT-IR),scanning electron microscopic(SEM) and X ray diffraction spectra.The cellulose have typical network structure with nanometer ribbons and high crystallinity.