Production of Bacterial Cellulose with Cassava Hydrolysate as Raw Material by Static Fermentation

Using cassava hydrolysate as fermentation medium,bacterial cellulose(BC)was prepared by fermentation of Komagataeibacter xylinus with cassava hydrolysate as the substrate of fermentation medium. The temperature,liquid volume,initial pH value,cassava hydrolysate addition,and inoculum amount were studied by single factor experiment. The yield of bacterial cellulose production,reducing sugar consumption,pH,bacterial cellulose moisture content and rehydration rate during the fermentation process were also detected. Then the bacterial cellulose obtained by fermentation was characterized by elemental analysis,infrared spectroscopy,thermogravimetric analysis,scanning electron microscope and X-ray diffraction. The results showed that the optimum conditions for the fermentation of cassava hydrolysate to produce bacterial cellulose were as follows:temperature 30℃,liquid volume 75 mL,initial pH6.0,cassava hydrolysate addition 3%,inoculum 6%. During the bacterial cellulose fermentation,the pH decreased from 5.51 to 2.66,while the reducing sugar content decreased from 32.1 g/L to 10.2 g/L.Finaly,5.75 g/L of bacterial cellulose was obtained by fermentation for 9 days. The moisture content of the obtained bacterial cellulose was 96%~98%,with the rehydration rate of 50%~58%. The results of elemental analysis indicated that bacterial cellulose was mainly composed of three elements of C,H and O,which was consistent with the content of various elements in cellulose. Infrared spectroscopy reveals the characteristic absorption peak of bacterial cellulose. The thermogravimetric analysis showed that the bacterial cellulose had the largest weight loss at 290℃,and the weight loss rate reached 32.33%. The diameter of bacterial cellulose was observed between 100~500 nm by scanning electron microscopy. The crystallinity of bacterial cellulose obtained by XRD analysis was 93.4%. Therefore,cassava hydrolysate is a carbon source that can replace glucose to produce bacterial cellulose during the fermentation.