Characteristcs And Mechanism Of Bioflocculant-production Strain Ochrobactrum Sp. W2 From Corn Stover Hydrolysate

In today’s world, inorganic flocculants and organic flocculants are widely used,which threatens potentially human health. Bioflocculant, as a kind of efficient, safe,and no secondary pollution purifying agent, has been increasingly called great concerns and attentions from people. Currently, this issue has become a critical one in how to reduce costs of Bioflocculant’s synthesis in the process of Bioflocculant study. Its aim is to promote industrial application of Bioflocculant. This issue can be solved by low-priced hydrolysate and breeding of efficient flocculant producing strains. This study is based on breeding of efficient flocculant producing strains from hydrolyzate of flocculants produced from corn stover, optimizing hydrolysis conditions of corn stover, showing a clear-cut content of pentose and hexose in hydrolysate, and medium compositions of stover hydrolysate suitable for efficient production strains. In the optimized condition, the influence of phosphate on strains producing flocculation characteristics is investigated. The outcome is that the reducing the amount of phosphate can lead to further reduction of the cost. This dissertation, analyzing active constituents of Bioflocculant and Zeta, probes into the mechanism of flocculation.This research exploits response surface methodology and High Performance Liquid Chromatography（HPLC）, confirms hydrolysis conditions of corn stover and the content of revertose in the hydrolysate, manufactures flocculant producing medium, and breeds efficient flocculant producing strain, and makes an analysis of flocculant composition by using Fourier Transform Infrared Spectroscopy（FTIR）.The results display corn stover hydrolysate contains 18.9g/L xylose, 6.63g/L glucose, and 5.22g/L arabinose under the circumstance of 2%（ v:v） acid concentrationand 2 hours steam explosion in 120°C. The experiment demonstrates W2 as Ochrobactrum sp., W4 for Bacillus subtilis, by breeding two efficient flocculant producing strains simultaneously using pentose and hexose, and polyphasic taxonomy appraisal analysis, such as form observation, physiology and biochemistry, identification of fatty acid, molecular biology of 16 Sr DNA gene. The flocculating rate of W2 and W4 attain 95±2%, 94±2.2% respectively. The main flocculating active compositions are polysaccharide and protein. The Strain W2 is taken as the object of study because Strain W2’s capacity of using xylose is greater than Strain W4.By Response Surface Methodology（RSM）. Taken Ion Chromatography（ICP）,High Performance Liquid Chromatography（HPLC）, the dissertation analyzes the influencing factors of Bioflocculant synthesis, studies the impact of furfural onflocculant characteristics, explores synthetic process by dynamic model. The results reveal that the output of synthetic bioflocculants is 3.8g/L and the flocculating rate reach 92%, with W2 using the hydrolysate in p H7.0, and fermentation temperature30°C, table speed is 140 RPM, cultivating for 18 h in optimized conditions. The main factors which influence the production of flocculants is p H（54.6%） and TOC（47.4）. Furfural, hydrolysis byproduct of corn stalk, can promote the growth of W2 bacteria.By Ion Chromatography, the dissertation studies P element in the hydrolysis process of corn stover, indicates the effects of phosphate on flocculant characteristics. The results prove that the amount of adding Phosphate affect the synthesis of Bioflocculant. The order of the amount of synthesized Bioflocculant as follows: 0g/L>2g/L>1g/L>0.5g/L phosphate. Furthermore, PO₄^3-can strengthen flocculating activity of Bioflocculant. Ca²⁺can also strengthen the activity of Bioflocculant if there is no PO₄^3-. The mechanism on Ca²⁺ strengthen W2 bioflocculant was probed.