| Acetobacter strain M12 was isolated from membranous vinegar which showed higher and steadier BC production. According to The Common Methods of Determinative Bacterial and Bergey's Manual of Determinative Bacteriology(ninth edition), M12 was characterized Acetobacter xylinum. The optimum fermentation condition of M12 was: 6% of inoculum size , fermentation temperature 30 C, pH 2.5-7.7, culture time 6 days.By orthogonal design of experiment, the production of BC increased by 40% with the optimized medium, which consisted of glucose 2.5%, yeast powder 0.75%, peptone 1.0%, Na2HPO4 1.0%, acetic acid 1.0%, pH 5. When cultured 6 days at constant temperature 30掳C, the yield of BC was 4.16g/L.The method of producing BC by static cultivation is not applicable to large-scale production of BC. Thus This paper mainly discussed the condition of producing BC used a airlift reactor designed by our lab in order to accumulate data for large-production. When the ventilate volume was 2vvm, the yield of BC was2.40g/L. Meanwhile the operational conditions of batch culture stage in BC fermentation were studied. The production of BC with fed-batch fermentation increased by 2.44 times than that of the batch culture.The average thickness (or the grammage) of the final dried pellicle is a important parameter when considering the application of BC. Thus the dynamical model of controlling the thickness of BC is established.The detailed metabolic network of BC biosynthesis was established. The control mechanism of BC metabolism was analyzed by metabolic flux analysis.Based on the static fermentation, this paper analyzed X-ray diffraction patterns, permeability and holding water capacity. The important data could apply to medical application. Meanwhile this paper studied the combination characters of plant cellulose and BC.The production technique of BC is simple. Without toxic substances, BC has satisfactory organism suitability, fine ductility and holding watercapacity so BC is advantageous to skin constitution growth and can restrain infection. This paper mainly studied the possibility of BC applied to be as a temporary skin and the biological dressing in wound and burn. Firstly the treatment of BC to the skin of deep II burns rats was studied. Compared with contrasted , the healing rate of treatment rised after burn 21 days, which states the cellulose can accelerate the wound healing in some degree. But the healing area between the treatment and contrasted was not remarkably different during most of the time. Secondly the acceleration of BC to the wound healing of rats was studied. Compared with contrasted, the wound healing rate of treatment remarkably improved after 7 days, 14 days, 21 days and 28 days; The histology filleting indicated that the BC could permit the fibroblast and blood capillary to gradually grow into the cellulose pellicle, which interpreted that the BC had therapeutical effect on the skin wound. At last the study of embedding BC under derm indicated that there was no obvious sign of acute immune rejection, slight inflammatory response inducing the organic which lasted short time and gradually extincted till last. The experiment clared the BC had poor foreign body reaction and was advantageous to the growth of blood vessel and cell. So BC is probable to be a new material of skin tissue engineering.
|
PDF Full Text Request