Bacterial Cellulose Pellet Production By Gluconacetobacter Xylinus In Agitated Cultivation

Bacterial cellulose (BC) is the most important one in microbial cellulose produced by bacteria, the BC produced by Gluconacetobacter xylinus has been widely applied into food, medical, material, papermaking, acoustic equipment,etc. At present, the main mode of fermentation is producing bacterial cellulose gel membrane under still condition,which not only needs a big area, but also be polluted easily.In order to break that traditional mode and develop a new type bacterial cellulose, agitated fermenting conditions were studied to produce regular bacterial cellulose pellets.Designment and results of the experiment were as follows:1.18strains of high and stable ability to produce cellulose were selected to be cultivated under agitated condition. But there were only6strains of them being saved for they could produce BC pellets when they were cultivated in agitation, finally strain Y15’was used in the following experiment due to its high quantity of BC pellets, and high ability of producing BC in still condition.2. The effect of the fermentation conditions of Y15’on the BC pellet production were studied by single factor experiment. The factors included coconut water volume,category of carbon sources, speed, and so on. The results showed that coconut water volume, concentration of carbon source, ratio of starch and sucrose, medium volume and speed influence the regular extent of BC and yield of BC pellet.3. In order to get more regular BC pellets, response surface method was used to optimize the fermentation conditions which can affect the size and yield of BC pellet to produce0.5-0.8cm pellets. The optimal condition was:28%coconut water volume, lOg/L carbon source with starch and sucrose(13:12), speed127r/min, medium volume58mL/100mL; The variance analysis result showed that:speed, medium volume and the interaction between them influence the yield of0.5-0.8cm pellets significantly beside the size of pellet.4. By adding different kind of starch, the result showed us that:not only the soluble starch can promote the pellet to be formed, but also the potato and cassava starch. Several experiments were designed to find out the internal reason for the effection, the result of the experiments showed that viscosity maybe the main reason.5. The BC pellet showed the higher water holding capacity than BC membrane, the pellet contained99.5%water but BC membrane just contained98.8%. When0.5g/L carrageenan was added in the broth, the BC pellets released water slowly. Texture of BC pellets was determined by texture analyzer, the results showed that there were no influence of thickeners added in the medium on the texture of BC pellet,and no significantly difference of the rigidity and chewiness between membrane BC and BC particles.