The Studies On Killer Toxin Produced By The Marine Yeast Pichia Guilliermondii

Killer yeast can produce a kind of anti--microbial exotoxin which is often calledKiller Toxin. They are usually some kinds of protein or glueprotein. The exotoxinsecreted by the killier toxin can restrain or kill some sensitive strains and it is alsoimmunity to the killer elements secreted by itself. It is found in the research that theOcean Killer yeast Pichia guilliermondii which is distilled from the ocean canrestrain the Pathogenic yeast which results in the emulsification disease of theswimming crab.This research centers around the bacteriostatic effect of GZ1killer toxin indifferent Concentration（0%，3%，6%，8%）, Temperature （15，20，25，30℃）and pH（3.0,4.0,4.5,5.0,6.0）conditions. The optimum conditions for the killerelements is NaCl Concentration0%, pH4.0and temperature15℃.This research studies the effects of salinity, temperature and PH towards thekiller elements produced by GZ1Killer toxin with the results that under theconditions of NaCl Concentration0%, pH4.0and temperature20℃,the power ofthe killer elements are the strongest.This research studies the influents of different nurture conditions towards theβ-1,3-Glucanase of the Marine killer yeast GZ1. It researches repectively about theinfluents of different nurture time（1d,2d,3d,4d,5d,6d）and different reactiontemperatur（e10,20,30,40,50,60℃）towards the pesticide biochemistry; the influentsof different nurture temperature（15,20,25,30,35℃）and different pH（4.0,4.5,5.0,6.0，7.0）towards the fermentation conditions; the influents of shake flask withliquid volume250ml and triangle bottle with liquid volume respectively as（20,30,40,50,60ml） towards the fermentation conditions; the influents ofinoculation（1,2,3,4,5,6%）towards the fermentation conditions; the test of the bestcarbon source（Glucose，Sucrose，Maltose，Glycerine，Lactose，Cornmeal;， Wheat bran dextrin and Soluble Starch）; the test of the optimal nitrogen source（Ammonium Sulphate，Ammonium Nitrate，Ammonium Chloride，DiammoniumHydrogen Phosphate，Carbamide，Beef Extract and Peptone）. The results of thestudy is that the optimum sample-taking time is3d, the optimum reactiontemperature is40℃,the optimum nurture temperature is20℃, the optimum PH is4.0, the optimum liquid volume is30ml for a triangle bottle with maximumliquid volume in250ml, the optimum is inoculation is3%, the best carbon sourceis Glucose and the optimal nitrogen source is Peptone.This study selects out a kind of strains which have stronger bacteriostatic abilityand more stable genetic trait by the compound mutation of the ultraviolet-sulfuricacid two este. Its bacteriostatic ability improves by22.7%, and after the secondround of selection the the enzyme activity of the glucanase improves by17.8%.This study tests about the best fermentation conditions of the strains which havestronger bacteriostatic ability and more stable genetic trait that is selected by thecompound mutation of the ultraviolet-sulfuric acid two este, studies about theinfluents of the rotation rate（100,150，200,250rpm）towards the fermentationconditions, the influents of temperature （15,20,25,30,35℃） towards thefermentation conditions）, the influents of different PH towards the fermentationconditions. It is found that best fermentation conditions in the fermentation tank iswhen the rotation rate is200rpm, the fermentation temperature is20℃, the PH is4.0. Under this kind of condition, the glucanase Pesticide Biochemistry is thehighest.The killer elements produced by the killer yeast is purified by the Gel filtrationof the DEAE-Sephorose Fast Flow and the Sephadex G75and the single bandwith the molecular weight in47.5kDa is got by the test of SDS-PAGE. Thepurified glucanase activity abilty contains killer protein, and it still exists in it theAntibacterial activity ablity.