Study Of Screening, Culture Condition And Enzymatic Property Of Psychrobacter Sp. Z-9

Strain Z-9with high histamine degrading enzyme activity was screened. Its identity wasdefined by morphological, physiological and biochemical reactions and molecular identification.The strain was Gram-negative bacterium. The colonies were pale yellow, round, smooth surfacemoist and neat edged on Zobell2216E medium plate after24h culture. The bacterium was straightrod with non-spore observed under optical microscope. The histamine-degrading strain Z-9wasbelonging to Psychrobacter sp. by molecular identification.The fermentation medium and fermentation conditions were optimized through single factormethod, FFD and CCD. The optimized medium contrained: glucose12g/L, diammoniumhydrogen phosphate8g/L, NaCl30g/L, ferrous sulfate0.006g/L, dipotassium hydrogen phosphate0.08g/L and0.04g of magnesium sulfate. The optimum fermentation condition was bottling30mL/250mL, temperature24℃, initial pH7.0,16h age,1%inoculum seed culture. Afteroptimization of fractional factorial experimental design and response surface methodology, theresult was obtained as: glucose16.8g/L, diammonium phosphate6.6g/L, NaCl30g/L, ferroussulfate0.006g/L, dipotassium hydrogen phosphate0.08g/L, magnesium sulfate0.04g/L,fermentation conditions: temperature21℃,1%inoculums volume, seed age of16h, initial pHof7.0, liquid volume30mL/250mL.The optimum reaction conditions of histamine-degrading enzymes were: temperature35℃,pH7.2. In the existence of Mn2+, Ca2+, Na+, Mg2+, the case of K+and other metal ionsincreased the enzyme activity, and for Zn2+, Al3+, Fe3+, Fe2+, Cu2+and other different metalions, the enzyme activity decreased, and there is a condition in EDTA Under live completelyinactivated. The maximum reaction velocity Vmax=156.25U/mL, Michaelis constant Km=0.22mg/mL.