Screening The Antimicrobial Activities Of Microorganism For Food Preservative And Study On The Active Substance For Them

Use Staphyloccocus aureus, Saccharomyces cerevisiae, Salmonella typhimuniunsIFO12529, Escherichia coli.O-111, Bacillus subtilis, Bacillus cereuss as indicatorspoilage. Then mix them with proper culture medium in order to get active bacterium.we have got about 600 bacteria from differen samples: soil, organic matter, pickledvegetable, traditional food, different kind of fungi, marine product, rotten plants. Weindicated and classified the most active bacteria: Bacillus Licheniformis, Bacilluscereus/, Bacillus polymyxa. We selected 1801 to study on their active substance.1801 was cultured in TYG medium for 48h at 30℃. The supernatant wascollected by centrifugation at 6000 r·min^-1 for 20 min. Crude extract of antagonisticsubstance was obtained by precipitation of the ferment, the pH of the supernatantadjust to 3, then extracted by 80％alcohol. Assays for crude extract inhibitingactivity were done on agar plates. The results showed that they were littlewater-solubility and dissolved better in weak alkal and were thermal-stable, resistantto proteinase K and stable in various pH. In order to get pure substance, we have triedmany methods: used acroporous resin and ion exchange resins to absorb, thendesorption. Then used HPLC to separate, then do LC-MS. LC-MS chart showed thatit have 1452,1466,1480,1494,1508are homologue, and 1030,1044,1058 is anotherhomologue. They maybe are the same as they have been published.The fermentation of Bacillus licheniformis 1801 was investigated throughsingle-factor test. The optimal ferm entation conditions are: initial pH 7.2, theinoculation was 5％. The orthogonal experiment was used to optimize the medium,use Trptone, Glucose, Yeast Extract powder. Do three levels. The best medium formula was got: Trptone 1％; Glucose 0.5％; Yeast Extract Powder 0.02％.14 actinomyces were got by using Micrococcus luteus as indicated bacteriumfrom 3930 actinomyces, then use double deck flat for the second screen. We selectedfive active actimyces. From their antimicrobial spectrum, we selected 2925 for furtherstudy. The result of the identification is Micromonospora sp.