Screening Of Cellulose-Producing Strain And Characterization Of Its Products

Some bacteria such as Acetobacter produces cellulose in liquid culture, the cellulose produced by bacteria is called bacteria cellulose or bio-cellulose. In comparison with plant cellulose, bacteria cellulose has been found to have a unique characters such as high purity, high crystalline, high tensile strength and bio-degradable, and is expected to be used as a new biomaterials in various industrial fields including food, textile, paper making, biomedical materials and chemical engineering. In this paper we screened a high cellulose-producing strain, and characterized of microstructure and partly properties of its products. The main results were as follows: 1. We obtained the BC producing bacteria system including F-99 and H from the nature. F-99 can produce BC, which was identified as Gluconobacter Oxydans, and H cooperated with F-99 was identified as yeast. Cultivated at 300C. the two strains produced 156.21 g/L after 7 days. This production is ten times as that of F-99. 2. The result of X-ray diffraction was as follow: not only crystallization of BC was belongs as I, but the characters of BC of mixed-culture were better than that of pure F-99. Using cellulase, the test showed that the pure cellulose is 91.6% in the pellicle. Except that, the cellulose pellicle can resist bacteria and has a good ability in sticking water. 3. Using these two strains, the liquid fermentation condition was optimized: glucose (2%) as carbon source, yeast extract (0.25%) and beef extract (0.25%) as nitrogen source, 0.115% citric acid monohydrate and 0.27% Na2HPO4 were. the optimal conditions for BC抯 yield. The ratio of F-99 to H was 6 to 1. The bacteria was cultured at 300C under pH 5.5 for 7 days. Then the yield was 287.87 gIL, it is 1.79 times as that of before.