Screening And Identification Of Antagonistic Low-temperature Spoilage Microorganism In Antarctic Bacteriaand Primary Study On Its Active Substances

Under the Antarctic extreme cold environment, cold-adapted microorganisms haveprominent advantages, and a series of special physiological and metabolic changes.Based on the above specialities of the Antarctic bacteria and taking the cold-adaptedbacteria strain as experiment object, this research filtered an antagonistic strain ofbacteria witch can lead to rot of fish, and implemented spicies identification of thisbacteria strain and preliminary research of active substance generated by this bacteria.(1) Taking the bacteria witch is extracted from the rotten fish in low temperatureenvironment as the indicator bacteria, and implementing the antagonism experiment byusing the method of tablet dibbling and tablet diffusion, a bacteria strain named AN325is filtered. By using the method of morphological characteristics observation,physiological and biochemical index determination, and analysis of16S rDNAsequences and phylogenetic tree, the AN325strain was identified asPseudoalteromonas.(2) As can be illustrated from the fermentation culture conditions, the strain issuitable to generate high active substance in the cold environment of10℃, whoseoutput is positively related to ventilatory capacity, and the strain can tolerate relativelyfar-ranging pH and relatively high salinity. The activity of antagonist substance isrelatively higher under the conditions of pH4.0and pH8.0. Glucose is the best carbonsource for the strain to generate antagonist substance; meanwhile the best nitrogensource is yeast extract powder.(3) The results of preliminary property test of the antagonist substance indicate that,the antagonist substance generated by AN325is a kind of extracellular products; theantagonist substance is sensitive to pH (the best pH for activity is11.0); the antagonistsubstance is sensitive to changing of temperature (the best temperature for activity is10℃, and with temperature increase, the activity decrease until disappear); the antagonistis sensitive to protease, pepsin, neutral protease, trypsin etc.(4) The antagonist substance can not be effectively precipitate by ammoniumsulfate precipitation. Some organic reagent as diethyl ether, ethyl acetate, and n-butylalcohol can extract the antagonist substance. Because boiling point of n-butyl alcohol isrelatively, activity of the antagonist substance will be affected. The effectiveness ofdiethyl ether is better than ethyl acetate. Diethyl ether extraction, rotary evaporationconcentration, and thin layer chromatography were implemented to the fermentationsupernatant of the bacteria strain, and the result had4sampling points. Migration rate ofthe4sampling points are0.102,0.742,0.829, and0.857. The second, third and forthsampling points showed activity after activity test. Research results showed that the bacteria strain generated more than one kinds of antagonist substance, and advanceresearch is still underway.The above research focused on further development of microbiology preservativeswhich are more appropriate for sea products and low temperature preservation of otherfood, and is safer than the physical and chemical methods.