Strain Selection And Facilities Optimization For Bacterial Cellulose Submerged Fermentation

As one of the newest biomaterials, bacterial cellulose is turning to be the hotspot . However, the bacterial cellulose could not be produced in large-scale in industries at present because of its static fermentation method in shallow pan which takes a long time , a large ground and tough work intensity .On the other side, bacterial cellulose is worth being researched for its special characteristics such as its high rate of synthesis , high chemical purity , good water absorption and good mechanical strength that also make it valuable in different areas .Therefore, we will do the systemic study on the raise of production of bacterial cellulose by improving the technology and researching its characteristics are of great significance.The research has screened the strain which is high-output and stable in continuous passage. After that, a strain which has high energy and adaptivity to shaking culture was obtained by semicontinuous culture and the yield enhance by 38.80 %. The research has explored parts of fermentation condition as well. The result indicated that the best liquid volume is 75 mL/250 mL, the best fermentation temperature is 28℃.Orthogonal experiment design was used to optimize zymotechnique of bacterial cellulose. Using orthogonal design optimization, factors of original pH, liquid volume, the rate of fructose and glucose and the content of yeast powder were optimized for bacterial cellulose production. The influence orders of the factors are liquid volume, the content of yeast powder, the rate of fructose and glucose and the original pH. And the optimal zymotechnique are original pH 6.0, 50 mL/250 mL flask, the ratio of fructose and glucose is 1:1, yeast powder 14 g/L. The bacterial cellulose production of 13.493g/L was reached under the optimum process.Acetobacter xylinum was cultured in shaking and static flasks and the Fourier transform infrared spectra, the water-holding capacity,the water reabsorbing capacity and the ash content of bacterial cellulose were analyzed.The scan electron micrographs showed that the bacterial cellulose produced in static culture was different from that in shaking culture.Both of them have similar Fourier transform infrared spectra.The cellulose from shaking culture has better water-holding capacity and better water reabsorbing capacity but more ash content. What's more, the static-culture bacterial cellulose has good compatibility.On the base of the 5L blistering bioreactor, designed an improved-structure according to the BEX-11growth habit. After the comparison of the static culture and the state culture of different VC, it showed the production is 0.268 g/L in static culture and the production of culture of original structure is 1.078 g/L. When the improved structure bioreactor is used, the best production is 5.705 g/L when VC is 4L/min, the production is 3.783 g/L when VC is 5L/min.