| Bacterial cellulose (BC) was first described by Brown in 1886. It is an exopolysaccharide produced by some bacteria principal the genera Acetobacter, Sarcina and Agrobacterium. Special attention has been given to strains from Acetobacter, specially Acetobacter xylinum. From the cellulose composition, BC is a linear condensation polymer consisting of D-anhydroglucopy- ranose units (glucose unit for convenience) joined together byβ-1,4-glycosidic bonds (thus a 1,4-β-D glucan) like plant cellulose. BC has unique structural and mechanical properties and is highly pure as compared to plant cellulose. Due to its excellent physical and mechanical properties, BC is applied widely in the pharmaceutical, bio-medical, paper engineering and food industry as the world excellent performance of new biological nano high-tech materials. Extensive application demand mass industrial production to meet its requirement. However, the problems of the high economic costs of carbon sources and relative low-yield strain become a bottleneck for BC's industrial production and extended applications.This rearch hydrolyzed inulin by sulphuric acid and optimized its acid hydrolysis conditions with Single-factor and orthogonal experiments. Then fermented bacterial cellulose under static condition with inulin and inulin liquid of acidolysis for carbon source instead of conventional carbon source. at last comparative the performance of BC between inulin and inulin acid acid hydrolysis solution fermentation. The results shown that the the optimum conditions of acid hydrolysis was the ratio of gardenia to liquor of 1:10, the hydrolysis temperature of 100℃, the hydrolysis time of 2 h and the sulphuric acid concentration of 1.5 mol/L. Under this optimized conditions, the yield of monose from inulin acid hydrolysis was 96.35%. The effect of different factors on acid hydrolysis was solid solution ratio> temperature> sulphuric acid concentration> hydrolysis time. Then ferment bacterial cellulose under static condition with inulin and inulin liquid of acidolysis for carbon source, after weighing the dry weight of BC membrane and calculate the yield, the result dicated that the yield of BC fermentation by inulin achieve the highest yield 16.06 g/L, and then the glucose and fructose a mixture of sugar glucose, fructose, the lowest yield of BC fermentation was by inulin acid solution with BC yield of 8.466 g/L. The results of mechanicaland properties of BC membrane characterized by measuring tensile strength indicated that the mechanical property of BC membrane produced by fructose fermentation is the best,glucose is the worst. Inulin and mixture of fructose and glucose are better than inulin acid solution at absolute tensile strength while worse than inulin acid solution at relative tensile strength.There are some water-soluble bacterial cellulose with low olecular weight existing in fermentation liquor of Acetobacter xylinum. This paper firstly investigated the changes of output of water-soluble bacterial cellulose and insoluble bacterial cellulose in Acetobacter xylinum shaking cultivations at various fermentation time and rotation speed and by adding various organic acids, polysaccharide and glass drops. The results showed that the yield of soluble bacterial cellulose reach a maximum of yield at the fifth day, while insoluble BC reach a maximum of yield lat the seventh day; Adding citric acid can significantly improve the output of soluble BC, however, acetic acid and lactic acid promote BC production. Addition of suitable amount of glass beads can help the synthesis of bacterial cellulose.In the end, methods for preparation of a kind of BC powder were studied and drying process was optimized in the experiment. |
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