| Magnetotactic bacteria represent a kind of prokaryote which could swim alonggeomagnetic field line. They are all Gram-negative bacteria, and could make use of iron ion tosynthesize nano-sized ferromagnetism crystal aligned in lines which called magnetosomes.The purpose of this research is to isolate magnetotactic bacteria from the soil, optimizethe medium and culture condition and study on the application of the magnetosomes used asenzyme carrier. First we got the soil from Anshan iron district. By richment cultivating andplate cultivating with semi-solid medium, we got the bacteria. Then we used single-factor andorthogonal experiments to found out the optimum medium and the best culture condition.Using home-made separation column device, ultrasonic fragmentation and centrifuge, we gotalmost pure magnetosomes with membrane. We used these magnetosomes to prepare gelatinmagnetic microspheres and immobilized β-amylase on them through cross-linking method.The magnetotactic bacteria were Gram-negative bacteria and have good response tomagnetic field. The optimum medium should have0.1g sodium acetate anhydrous,0.25gammonium chloride,0.5ml KH2PO4-K2HPO4buffer （pH6.7）,1ml vitamin mixture （10×）,1mlmineral mixture （10×） and2ml0.01M FeCl3solution per liter. The bacteria should bestanding cultivated at28℃and the pH of medium should be6.7. The magnetosomes weresphericity and the average diameter was80nm. The average diameter of gelatin microsphereswas between280nm and300nm. When add0.5ml toluene solution of glutaraldehyde and theconcentration of albumin solution was10g·L-1, the able of magnetic response and dispersionwas the best. When we used gelatin microspheres to immobilize β-amylase, the optimumquality score of glutaraldehyde solution was0.06%and the volume of enzyme was1.5ml.The mass activity of immobilized enzyme was2753.64U·g-1, and the activity recovery was76.86%. The optimum temperature and pH of the immobilized enzyme was70℃and5.5. |
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