Selection Of Biological Degumming Strains For Ramie And Research The Condition Of Compound Fermentation

China is a big country for producing and exporting ramie of the world, its various ramie products perennial best-selling all over the world. Ramie contains most of the cellulose, besides the25percent to35percent of the quality is colloid. Therefore raw ramie can’t be directly used in spinning, have to carry on degumming process. For many years, the chemical degumming method that using the strong acid, strong alkali, high temperature and high pressure for cooking and refining, which can bring about severe environmental pollution, high cost, and impairment of fiber’s quality and yield. So in recent years, the biological degum method become the hotspot in researching ramie for domestic and foreign researchers. Which for the characteristics of high yield, high quality, energy conservation, environmental protection and has remarkable economic and social benefits.In this research, taking the soil of plantting ramie field and retting ramie pool as the sources, two effective strains were obtained from plate screening, through the morphology observation and biochemical experiments to determine theirs types. Then optimized the strains’culture media for enzyme production, and measured curve of enzyme production. Finally, made use of the two kinds of strains to conduct associately degumming, and optimized the fermentative condition and enzymatic degumming process conditions.（1） Screening and mutation for efficient bacteria of ramie biological degummingThe advantage bacterium CJ2sieved from the soil of retting ramie pool. It’s affirmed that CJ2was Bacillus licheniformis after the colony morphology, physiological and biochemical indexes inspection. The best mutant B2was gained from the strain CJ2carried out by UV mutagenesis for60seconds, whose degumming loss percentage was22.8percent, higher29.5percent than that of the strain CJ2. Through spread generation, fermentative experiment proved its genetic traits steadily. So the strain B2was a suitable choice as the receptor bacteria in the microbial degumming of ramie.（2） Selection of efficient ramie biological degum fungus and optimization of the fermentative condition for enzyme production.The advantage bacterium MCZ2sieved from the soil of retting ramie pool. From the reference material, it’s preliminarily affirmed that MCZ2was aspergillus by the morphological and microstructural observation of spore and hypha. Through the single factor experiment to determine the proper carbon sources, nitrogen source and metal ion species and initial pH value of the culture medium for MCZ2liquid fermentation. Then, the best condition of MCZ2ferment produce pectinase and hemicellulase gained through orthogonal test, which were consisted of10g/L bran,6g/L yeast cream,0.1g/L CaCl₂,1g/L KH₂PO₄,0.5g/L MgSO₄7H₂O,5g/L NaCl,100mL water, initial pH value at6.0, culture medium volume was100mL. In proof experiment under the optimal condition, measured the highest activity of pectinase and hemicellulase respectively was135.5U/mL and318.8U/mL, improved35.1percent and68percent respectively than strains produced enzyme activity in not optimized conditions.（3） The research of associate degumming condition by using compound microorganismThe two efficient germ and fungus as starting bacteria, which producted liquid enzymes mixed for degumming ramie associatively. Obtained the best degumming conditions was: the germ and fungus seed liquor of inoculative amount respectively was6percent and11percent, the ratio of water to material was15:1（mL/g）, degumming initial pH value at6, the temperature at35℃, revolving speed at150rpm, degumming time for50h. Ramie treated in this degumming conditions, the degumming rate can attain to31.9percent, ramie fibre fineness was6.29±0.13dtex, fiber fracture strength was4.28±0.14cN/dtex, which conform to the standards of second class ramie.After treated with dilute alkali liquor simply, Rate of residual gluey content in ramie fibre can fall below2percent, and reach spinning standards of ramie.（4） Representation and analysis for the ramie fibre with before and after bacterial degummingThrough the method of infrared spectrum test the ramie fibre with before and after bacterial degumming, it conclude that enzyme secretion producted by mixed strains changed molecular structure of gluey composite material in ramie fibre, increased molecular unsaturation, activated the macromolecules’ performance of chemical reaction, thereby improved the sensitivity of gluey molecule interact with enzyme matter, make the glue easier degraded and wiped off. Meanwhile, using electronic microscope scanning test proof that the reticular gluey composite material in ramie fibre affected associatively by two kinds of enzymes, after that obtained more smooth, neat and slender ramie fibre, the degumming effect was very obvious.