Study On The Biological Degumming To Straw Of Eichhornia Crassipes

The flooding of Eichhornia crassipes (E. crassipes) in water body had broken the biodiversity of aquatic ecosystem and threaten the human production, living and health. E. crassipes had been list as one of the ten kinds of harmful grass. How to control and utilize it as a kind of resource is attracting more and more attention. Similar to other plants, cellulose, hemicellulose and lignin are the main chemical constituents of this plant. Cellulose is the one of the main biomass resources. Microbial method can be used to remove noncellulose (called degumming) of this plant, to obtain high content cellulose, for further utilization of cellulose, it is important components for the new utilization approaches of E. crassipes. This paper on the Eichhornia crassipes's biological degumming included aspects as following.1. Determination of chemical composition contents of E. crassipesThe determination of chemical composition contents of E. crassipes was conducted according to The Determination Method of Chemical Composition of Ramie GB5889-86. The results showed that the contents of different components are different in different parts of this plant. In the leaves, the content of lipid is the highest, pectin and lignin are all the lowest. In the stems, the contents of lipid and water soluble substances are all the lowest; the content of hemicellulose is the lowest in the roots, but highest in the leaves, being 52.94%. The lignin content in leaves, 12.65%, is the lowest. The cellulose content in stems is highest, being 17.23%.2. Screening of degumming strains of E. crassipes and degumming testUsing congo red-broth agar plate to select five strains from the leaves and stems of plant, the ponds that E. crassipes grow near Lake Nanhu of Wuhan City. Through comparison of the activity of pectin and xylan, the degumming rate among these five strains, Al strain was determined as the ideal degumming strain of the E. crassipes. Under the condition of inoculation amount 4%, 35℃, pH 7.0, agitation speed 145 r/min, cultivating for 72 hours, the activity of pectin and xylan were 72.69μg/mL·min and 45.72μg/mL·min respectively, the degumming rate was 31.89%.3. FTIR analysis of the celluloses obtained by different methodsThe FTIR spectrum of raw fiber of E. crassipes, fiber treated by Al strain and alkali treated fiber were compared, the results indicated, the hemicellulose and lignin were mostly decomposed by two ways - treatment by A1 strain and alkalization by NaOH. The degumming efficiency of alkalization was most obvious, but the damage to cellulose was also largest. The structure change of plant treated by Al strain lied between that treated by alkali and raw material.4. Single factor screening experiments for optimum fermentation conditions of Al strainThe screening experiments for optimum fermentation conditions of Al strain were conducted, using the plant as carbon source. The different factors for screening included form and concentration of nitrogen and, inorganic salt, temperature, and inoculation amount. The results indicated that the optimum degumming medium of Al strain was that NH₄Cl 0.1%, KH₂PO₄ 0.1%, MgSO₄·7H₂O 0.05% and pH 7.5. After cultivating for 72 hours, the activity of pectin and xylan were75.05μg/mL·min and 63.51μg/mL·min, respectively, the degumming rate was 33.37%.