Researches On Paenibacillus Polymyxa GA1 And Bioflocculant MBFGA1

Bioflocculants, having good flocculating activity, are the metabolic products of the microorganism, which are safe, non-toxic , easily cultivated, and can be biodegraded. Its main components are amylose, glycoprotein, nucleic acid, protein etc. Since the advantages of using bioflocculants in both environmental safety and economic over some other inorganic flocculants and organic flocculants, great attention has been payed to explore the bioflocculants mechanism and to investigate their characteristics in use. As a result, it is of great value in the research of bioflocculant.Paenibacillus polymyxa GA1 was a bacteria with high bioflocculant producing rate which was screened from soil by our lab. It could produce bioflocculant MBFGA1 with superordinary flocculability and decolourising property.This study focused on flocculability of MBFGA1and the situation of GA1's growth. The works remained: (1) research into the characteristic ,flocculability and influencing factors of MBFGA1; (2) study on the influence and mechanism of culture medium and its ingredients to flocculability; (3) study on the influence of phosphate to the parameter in culturing, chemical structure and producing situation; (4) study on the adsorption of Cu2+.The study showed, MBFGA1's main component was polysaccharide, and its thermal stability was superordinary. With CaCl₂, when pH>7,the flocculating rate of kaolin, soil waste water and coal waste water were above 95%,but only about 58% of landfill leachate.Different wastewater samples could be flocculated by phosphate in the culture medium with CaCl2 when pH >7.0. K₂HPO₄ and KH₂PO₄ were the key factors when the wastewater was treated by the microbial flocculant produced by GA1(MBFGA1).The contributing ions were PO₄^3- and Ca²⁺. The absolute value of kaolin's zeta potential could be brought down by these two ions to about 0, hence the stabilization of the colloid was broken. The unstable grains could be captured by the floccule of calcium phosphate, then the grains coagulated with MBFGA1 and settled. Although the wastewater could be flocculated by the culture medium alone, the effect was poor. The average granularity of kaolin was much bigger than that treated by fermentation and the floc properties are inappropriate for industrial conditions. Kaolin could also be flocculated with the help of BaSO4, but because of the difference of deposition, the effect was not as good as Ca3(PO4)2.The growth velocity in logarithm-time and the final productivity could be increased because of Phosphate,but there was no difference in division of cell growth curve with or without Phosphate. Phosphate was not necessary when MBFGA1 was produced,but the start-point of producing could be earlier with it. The final unit productivity with phosphate was 30% higher then without phosphate when the other factors were the same; The phosphate was some kind of buffering agent which made the pH steady.Steady pH was good for the cell growth. Both the MBFGA1with phosphate or without phosphate were polysaccharide, the only difference in structure was that there was R-C≡CH in the former but not in the latter.Paenibacillus polymyxa GA1 could adsorbed Cu²⁺, and the equilibration time was 8 min. This adsorption effect was surface adsorption, Cu²⁺ did not participate the energy and principle metabolism. The adsorption effect of GA1 in different phase was different, the effect of GA1 in stationary phase was poor, and than the effect was rising faster,the best adsorption effect occurred in the phase of last logarithm-time,the adsorption rate was 74%.