Screening For Bacteriocin-like Producing Strains And Crude Bacteriocin-like Preserve Effect On Chilled Pork

The purpose of the study was to isolate symbiotic and epiphytic microorganisms from8species fishes collected from the sea area of Zhanjiang.Antibacterial producing strainswere screened form them by oxford piate assay system.And the identification andphylogenetic analysis of representative srtains based on partial16S rRNA gene sequenceswhich had broad antibacterial spectrum,strong antibacterial activity.By means of excludingthe effect of acids and hydrogen peroxide,eventually, selects the strains were sensitive toproteases and assumed them as bacteriocin-like producing substance strains.The biologicalfeatures of bacteriocin-like producing strain and its bacteriocin were analyzed.Andpreservation effect in chilled pork was studied.The main results were as follows:（1） Among of277strains of the symbiotic and epiphytic microorganisms,63strains haveantagonistic activity which accounted for22.7%.The identification and phylogeneticanalysis of22representative srtains based on partial16S rRNA gene sequences showed:6strains were Bacllius sp.has the highest ratio;2strains were Psuedomnoas sp.;3strains wereLactobacillus sp.;2strains were Psychrobacter sp.;The rest were Pseudoalteromonas sp.、Micrococcus sp.、Rothia sp.、Citrobacter sp.、Cobetia sp.、Paracoccus sp.、Staphylococcussp.、Brevibacterium sp.and Brachybacterium sp. respectively. And3strains（ZJHD2-58、ZJHD5-23、ZJHD2-31） could represent potential new species。（2） After ruling out organic acids and hydrogen peroxide,the cell-free liquid culture ofstrain ZJHD3-06showed high inhibitory activity against Listeria monocytogenes.But thecell-free liquid culture showed inhibitory activity against Listeria monocytogenes reducingto different degrees by Trypsin, pepsin, proteinase K and papaintreatment.Therefore,Theinhibitory substance produced by ZJHD3-06was Proteins or polypeptide sassumedbacteriocin-like substance.（3） The strain ZJHD3-06was identified as Bacillus amyloliquefaciens based on theresult of its16S rRNA gene sequence homology,the physiological and biochemicalcharacteristics.（4） The biological features of the bacterioncin-like substance showed that60% （NH₄）₂SO₄can salt out bacterioncin-like substance much more.It has good stability againsttemperature,the antimicrobial activity only have2.20%loss suffered under the temperatureof80℃for15min.pH had significant effect on bacterioncin-like substance,the antimicro-bial activity is not affected at pH6.0,and pH,which is less or more than6.0,had greatinfluence on bacterioncin-like substance. The inhibition spectrums of the bacterioncin-likesubstance was very wide,it could inhibit some gram positive bacteria、some gram negativebacteria and fungus.（5） The bacterioncin-like substance produced by ZJHD3-06showed great potentialapplication in preservation of chilled pork. And it has much better effect than control.Itcould extend the shelf-life of chilled pork to6-9days at4℃. The bacterioncin-likesubstance can effectively inhibit the growth of L.monocytogenes. It can enhance thesecurity of chilled pork and has broad prospects as biological preservative for chilled pork.