| Bacterial cellulose (Bacterial cellulose, BC) is a kind of extracellular microbial cellulose, produced by microorganism. Compared with plant fibers and animal fibers, it has a high water holding capacity, high crystallinity, ultra-fine features and ultra-pure network structure. Bacterial cellulose has a high use value and has a very wide range of commercial prospects.,such as the food industry, paper industry, chemical industry, pharmaceutical industry and so on.However, due to its high production cost, so its application has been greater restrictions. In order to improve the yield of bacterial cellulose production, and reduce its costs, The strain J2 was treated by high hydrostatic pressure,and effects of high hydrostatic pressure(HHP) treated on the character of strain J2 was studyed.it provided a theoretical basis for the mutation of BC-production strains; then the parameters of fermentation process were optimized which established the basis for industry.and the beer yeast was used as the raw materials of BC-production, which layed the foundation of industrial production of bacterial cellulose The results of this research were as follows:①The effects of high hydrostatic pressure on strain J2 were significant. The death rate increased with the extension of treatment time and increased with the treatment pressure rising.②The HHP-treated strains were showed bacillus and it is shorter that of untreated strains Under the microscope, and the HHP-treated strains present a spherical bacteria in the liquid medium and it is as 3 to 4 times as that of untreated strains. The high hydrostatic pressure had little effects on the physiological and biochemical characters,but it partly impacted the colonial morphology. While the HHP treatment had much play in utilization of strains on some of the carbon and nitrogen sources,such as lactose,mannitol,beef extract,peptone,and so on. After treated by HHP,the ability of BC biosynthesis of strains was obviously improved and the yield of one HHP-treated strains was as 1.485 times as that of untreated strains, and the growth rates of strains also increased.③The fermentation parameters of strains J2A had undergone some changes, cell density was significantly higher than before the strain treated by high hydrostatic pressure during the fermentation process, the acidity of strain J2A is lower than before, and the strain on the utilization of carbon sources and nitrogen were more fully than before.④The fermentation conditions were confirmed.The parameters of fermentation conditions were as follows:seed age 20-22h, inoculums amount 9%, fermentation time 8d.⑤The fermentation medium was confirmed. The components of it were as follows: carbon source3%(glucose:sucrose=2:1), yeast extract 0.5%, K2HPO40.08%, MgSO41.62%, FeSO40.36%, ZnSO40.03%, citric acid 0.05%,0.7% ethanol, Under this fermentation medium, the yield of BC was as 2.85 times as that under initial fermentation medium.⑥When beer waste yeast was treated by high-speed homogenizer, ultrasonic, microwave, that yeast:water reached at 18:100, the yield of BC-production reached to the highest value, and among these 4 methods, The effect of ultrasound is the best, yeast fermentation yield of bacterial cellulose obtained the highest, reaching at 26.081g.⑦MgSO4, ZnSO4, FeSO4, K2HPO4 were added in beer waste yeast treated by ultrasound and found that MgSO4 has some inhibitory effect on the production of bacterial cellulose, when ZnSO4, FeSO4, K2HPO4 were added,they all had a certain promoting role in the production of bacterial cellulose, in particular the effect of FeSO4 was more obvious, and when the concentration of FeSO4 was 0.1%, the yield of bacterial cellulose reached at the highest value,34.084g.⑧The basic properties of bacterial cellulose membrane,obtained from beer waste yeast fermentation of did not happen much change,they were high moisture content, rehydration ratio. |
