Microbial Flocculant MBFGA1Preliminary Structure Identificaiton And Research On Flocculation Mechanism

An highly efficient producing flocculant of Bacillus GA1was screened outfrom the soil of Yuelu Mountain using conventional bacterial separation method. Themicrobial flocculant, MBFGA1, which generated in the metabolic processes of GA1,has excellent flocculation effect on most of wastewater and production potential inthe industry, thus, it has better prospects for practical application.In this research,the component, molecular structure identification and flocculation mechanism of theMBFGA1were focused, which can provide the theoretical basis.of the molecularbiology or industrial application of MBFGA1.In the present study, the coarse product of MBFGA1was obtained fromfermentation liquor (obtained from the piecewise training method), and MBFGA1fine product was acquired through purificating the coarse product using sevagereagent. With the flocculating rate of kaolin as index, flocculating activity analysisof ermentation liquor, coarse product, MBFGA1fine product and extraction residuefermented liquid was conducted, and it was confirmed that MBFGA1fine productwas nuclear effective component of the micro-bioflocculant. By employing UV fullspectra scan, phenol sulfuric acid method and coomassie blue staining, MBFGA1fine product was identified to be polysaccharides, which has more than99%sugar.MBFGA1fine product was separated as MBFGA1-1and MBFGA1-2through twicegel chromatography separation filter. The structures of them were analyze d adoptinghigh-performance liquid chromatography (HPLC) and gas chromatograph (GC).Result showed that: MBFGA1-1was homogenous with the weight of1.18′106D andmainly composed of xylose, mannose, glucose (0.3:1:1.09), and a bit of rhamnose;MBFGA1-2with the molecular weight of3.08′103D, and rhamnose, xylose,mannose, galactose and glucose (0.68:0.28:1.82:1:3.73) as its monosaccharideformation.Then using the zeta potential analyzer, environmental scanning electronmicroscope (ESEM), fourier transform infrared spectroscopy (FTIR) and nuclearmagnetic resonance spectrometer (NMR) to analysis the structure of MBFGA1,MBFGA1-1and MBFGA1-2,which resulted that the molecular structures ofMBFGA1, MBFGA1-1and MBFGA1-2were structurally similar and had a linearlong chain molecular structure, in which-glucosidic bonds primarily existed amongmonosaccharides, and the rest of the small molecules and molecular chain of certain groups combined to form a branched chain. MBFGA1, MBFGA1-1and MBFGA1-2perssads with negative groups such as hydroxyl, carboxyl, methoxy which canConduct to the flocculation easily,and the zeta potential value of the flocculantsolution was also corroborated the presence of a large number of molecules within anegatively charged groups.The main function between between MBFGA1and particulate matter was theionic bond in the flocculation body,which formed by complex physical and chemicaleffects.The large amount of molecular and intramolecular hydroxyl, carboxyl andother polar groups were the main reasons that MBFGA1has a strong flocculation.The main flocculating mechanism was adsorption bridging, meanwhile the highmolecular weight and polar groups made the long chain structure molecules wellstretched, and played good role in adsorption bridging.