Effect Of Magnetic Field On The Cells Growth And Inulinase Biosynthesis Of Kluyveromyces Fragilis

This dissertation investigated the effect of static magnetic field and pulse electromagnetic field on the cells growth and inulinase biosynthesis of Kluyveromyces fragilis, based on studing the properties and biosynthesis conditions of Kluveromyces fragilis inulinase. The mechanism of the effct of magnetic field was approached preliminarily.The optimum reaction temperature of inulinase with K. fragilis is 55 ℃ andoptimum pH4.4 when sucrose was used as substrate. At that time the maximal reaction velocity Vm equaled 202mmol · min^-1 and Michaelis constant Km was 250mmol. when used inulin as substrate, however, the optimum reaction temperature and pH, Vm and Km were 55 ℃, 5.2, 120mmol · min^-1 and 20mmol respectively. Inulinase with K. fragilis was fair stable to pH, temperature, same chemicals and magnetic field. The inulinase of K, fragilis is typical induced enzyme. Inulinase was induced by inulin. A lot of them were secreted into medium as extracellullar inulinase. Some of them were bound in cell wall.The ratio of C to N affected the secretion of extracellular inulinase. The cells growth conditions of K. fragilis were initial pH 5.5 6.0, 28 ℃ about 26 28 hours in shake flasks ( 200rpm ) in the medium YID. Then it went into inulinase fermentation. The research result showed that the optimal pH was 6.0, inulin concentration 2% and the ratio of C to N 1.3, respectively in the medium for inulinase bionsythesis. The fermentative temperature was controlled at 28 ℃ before 30 hours and 32 34 ℃ after that. The yield of inulinase was 340U/ml and extracellular inulinase 245U/ml at 60 hours, accounting for 72 percent of the total inulinase yield.The medium flew through 60mT magnetic field at the flux of 8ml/min for 8 cycles in 40 minutes. Then, culturing for the production of inulinase, K. fragilis cells growth density and inulinase yield were increased 1.22 and 1.19 folds respectively.It was shown that because this magnetic field made some properties of fermentive medium, DNA copies of Kluyveromyces fragilis were raised , the cells...