A Development Of Gluconacetobacter Xylinum Freeze-dried Fermentation Agent

Nata or bacterial cellulose is produced by Acetobacter xylinum at the aireliquid interface of many organic substrates like pineapple pomace wastes, coconut water, tomato juice etc. Nata was used in desserts, fruit cocktails, fruit jellies etc, which was an important source of dietary fiber in fiber-poor foods. At present, the liquid traditional Acetobacter xylinum was mainly used in fermentation Nata company, and transferred between research institutions and enterprises, but has not been formally identified. Whereas, there were some disadvantages with this kind of Acetobacter xylinum, such as serious degradation, bacteria susceptible, short shelf life, and limited the industrialization of Nata production. In recent years, with the rapid development of low-temperature drying technology, direct investment and fermentation agent provided new ways to simplify the production process of fermented NATA products, and solved bacterial contamination and degradation problems. Therefore, in this research, the protective agent were selected, which was economical, safe and non-toxic. On this basis, the survival rate of Acetobacter xylinum was improved by a composite protective agent, which was obtained by response surface method.,1) By single factor test,10%skim milk,5%trehalose and1%glutamate was taken as single protective agent of Acetobacter xylinum, and then formulated using response surface analysis method and obtained the composite protective agent ratio of skim milk, trehalose, glutamate. The results showed that Acetobacter lyophilized cell could survive up to93.346%when the composite protective agent contained6.4%skimmed milk,0.075%trehalose and0.575%glutamate, These results suggested that bacterial protection agent had a significant effect on cell survival during lyophilization.2) Bacterial cells characteristics, including bacterial DNA disclosure, total antioxidant capacity of bacterial cells, bacterial cells SOD activity, bacterial cellulose synthase and ATP activity were determined in experimental(added a protective agent) and control group... The results showed that cell leakage and the reduction of total antioxidant capacity of freeze-drying process, the cell contents, SOD activity and the activity of ATP synthase and cellulose were inhibited by adding cryoprotectants. Total antioxidant activity and SOD activity of cells of various groups and various protective agent significantly improved while vitamin C was added in the protective agent.It was indicated that cells can be protected from damage during freeze-drying by cell protective agent and maintained good viability and physiological characteristics.3) The same number of viable cells of DVS Acetobacter xylinum fermentation agent and traditional fermentation agent were vaccinated to the same fermentation broth culture rehydration and activation, in the14day, the wet weight of NAT A were8.0346g/lOmL and8.5450g/lOmL, the yield were80.346%and85.450%respectively. There were no significant differences between the yield of bacterial cellulose.