Study On Technology Of Biological Deacetylation Of Chitin

Nowadays, green textiles are one of the hotspot of textile research. So the development of new green sizing materials and further reduction of chemical pollution have gradually importance for the textile field. Chitin and its derivatives have been regarded as green polymer materials, and have widespread application in environmental protection, food, household chemicals, medicine, and textile industry. Its derivative, chitosan solution has good adhesion and affinity to the textile fibers, and it can be used as the textile sizing agents, and applied to cotton, wool and chemical fibers. Entirely from the natural environment, this polymer material has its excellent properties to be developed for the new generation of green sizing material. Currently, the preparation of chitosan mostly uses concentrated alkali solution that is a pyrolysis method. However, this method does not produce the high-quality chitosan, and it is also easy to create a waste of energy and result in the environment pollution. Use of biological methods may avoid these problems, but also produce high-quality products with unique properties. This paper studies the processes of biological deacetylation of chitin deacetylase(CDA) on chitin, from cultivating bacteria, fermentation, testing and screening, and optimization of producing conditions of CDA, to the technical conditions of chitin deacetylation, and reach the optimal craft technology of biological deacetylation at last.Based on the resumption training and screening training of two selected enzyme fungi, colony morphology is observed. And through the color reaction of solid medium, the fungi with CDA activity can be detected and strained, and then CDA can be produced by liquid fermentation mediums. In order to improve the deacetylase activity, the culture conditions of pH, carbon and nitrogen sources, and the addition of metal ions, temperature and time on the impact of enzyme production are studied. By mwans of single-factor experiments, the best liquid culture conditions are: when the initial pH value of 6.5, adding soluble chitosan as a carbon source, peptone and yeast powder as an organic nitrogen source, adding Co²⁺, the fermentation temperatur of 31-33℃, incubation time of 96 hours. Under the condition, the producing CDA activity is relatively high. Absidia coerulea producing enzyme activity reached 0.355U/mL; Aspergillus nidulans reached 0.386U/mL.The paper also studies the effect of fermented enzyme in the role of deacetylation of degraded chitin. Take the CDA of Aspergillus nidulans in the deacetylation of degraded chitin as the research object, the craft condition of pH value, the temperature and the time on the effect of deacetylation are studied, mainly the degree of deacetylation as the judging criteria and the viscosity as a supplementary index. Through the orthogonal design experiment, the optimal process conditions are identified. The deacetylation of the chitosan product with degree of deacetylation 32.4% can be prepared and produced. In addition, the paper also carrys on the infrared spectrum test of the produced sample. The enzyme acts on the degraded chitin with certain deacetylation effect, and the structure of the product is fairly close to chitosan.