Study On The Screening Of Bacterial Strain Against Food Putrefying Bacteria And Antibacterial Compounds

Antagonistic bacterial strain against food borne pathogen were isolated and screenedfrom the drought soil of Gansu central habitat. The species of the antagonistic bacteria wasidentified through morphological, physiological and biochemical characteristics and16SrDNA method. The antibacterial activity ingredients were isolated from fermentation broth byusing macro absorption resin. The separation component was made a full spectrum scan todetermine its maximum absorbance peak in190nm to1100nm wavelength and purifiedfurther using HPLC. Molecular weight was determined by electro spray ionization massspectrometry. CNMR and HNMR were determined by NMR method, the structure of thecompound were determined. Then the separated active compounds were carried outantagonist S. aureus tests to identify the antibacterial substance and its some physicochemicalcharacteristics were determined.The results are as follows:1. An antagonistic bacterial strain A-2against food borne pathogen Staphyloccocus aureuswas isolated and screened from the drought soil of Gansu central habitat. And the minimuminhibitory concentration dilute gradient against Staphyloccocus aureus was10-6. Theantagonistic bacterial strain was identified Alcaligenes sp.A-2.2. The antibacterial spectrum of Alcaligenes sp.A-2was determined. The results showed thatAlcaligenes sp.A-2also had antagonism against Escherichia coli, Lactobacillus plantarum,Lactobacillus planetarium and Stapyloccocush epidermidis.3. The best resin was X-5, the best eluent was95%ethanol water. One component isolatedpreliminarily from fermentation broth by macro porous absorption resin X-5hadantibacterial activity against S. aureus. The preliminary separation component was made afull spectrum scan in190nm to1100nm wavelength. The component had maximumabsorbance peak at214nm. The three singlet compounds were further purified usingHPLC. The results of inhibiting S. aureus experiment proved that one singlet compoundhad antibacterial activity.4. The signal was APC(I+)245.4[M+H+], so the molecular weight was244.4. CNMR andHNMR of the singlet compound were determined by NMR method. The structure of thecompound was Cyclo-(D)-Pro-(D)-Phe.5. Some physicochemical characteristics of the compound were determined. The resultsshowed that the MIC against S. aureus, E. coli, S. epidermidis was0.1μg/mL, and thecompound had good stabilities to heat, acid-base, ultraviolet rays and light.