Study On The Mechanism Of Bioflocculant Production By Klebsiella Sp.NIII2 And Its Molecular Cationic Modification

Due to extensive sources,efficient,non-toxic and no secondary pollution, Microbia Flocculation is available in the drinks industry,food fermentation,bio-Pharmaceuticals a nd wastewater treatment. However, there is no commercial product on the market, mainl y because its low yield, high production costs, and flocculant fermentation process of in stability. It is imperative to improve the stability of microbial flocculant production and performance.The paper study the relevance between fermentation conditions and the production, structure,composition and activity of flocculation. It has practical and theoretical significance for production of microbial flocculant massively.In this paper, the optimization of fermentation conditions for the characteristics of glycoproteins bioflocculant production by Klebsiella sp. NIII2 and conditions of cationic were studied by IR, DR5000,MS and other research tools. It obtains the following results from the study.(1) The nitrogen source species had obvious effect on the NIII2 yield of Klebsiella pneumoniae. Sodium nitrate was the best nitrogen source, and the production of bioflocculant was 7.18g/L. Sodium nitrite with strong reducing ability can also be nitrogen source, but when its nitrogen is higher than 0.5g/L, the damage of bacterial cells caused by strong reduction, the production efficiency of bioflocculant is obviously decreased by NIII2.(2) The amount of sulfur element is essential for the synthesis of NIII2 flocculant. Sodium sulfate and sodium sulfate(sulfur element 16mg/L), the production of bioflocculant was up to 9.03g/L. And the degree of polymerization of flocculant, total thiol, two sulfur bonds were high, and the relative contents of protein were 11.8% and 16.58% higher than those without sulfur element.(3) When the NIII2 high-yield flocculant,it will secret a new low molecular mixture,it contained short chain peptides, oligosaccharides and glycopeptides, combined by covalent bonds.Plus the mixture in the medium,it can be made by bacteria in advance of secretion of flocculant, and improve the yield. Plus 10mg/L putrescine yield can be increased by 1.1g/L flocculant. While adding spermidine and putrescine are helpful to enhance the protein content and activity of the bioflocculant.(4) Cationic etherifying agent can make the bioflocculant cationic: each 10 g bioflocculant with 0.01 mol cationic etherifying agent and some of Na OH, proper temperature and reaction time 2h, obtained the Zeta potential was about to +16.5m V cationic flocculant and the helpless agent under, has good flocculation effect.The results of this research are the foundation for the industrial production of flocculant.