Isolate And Genetic Analysis Of Psychrotrophic Lactic Acid Bacteria From The Intestinal Tract Of Cold-water Fishes From Xinjiang

Object:Among the large number of complex structure of microbial communities parasites in the gut of theanimal in low-temperature environments, Lactic acid bacteria was recognized to be beneficial for the host.Lactic acid bacteria shows great potential application value in biological preservation for their lowtemperature adaption. In this study, Lactic acid bacteria with low temperature tolerance were screened outfrom cold-water fish intestinal(Irtysh River, Altay, Xinjiang). This study is meaningful in mining thediversity of species and heredity of Lactic acid bacteria, providing excellent strains for the development ofbiotechnology in Lactic acid bacteria with low temperature tolerance, also further refining Lactic acidbacteria resource in China.Methods: With the MRS, Elliker medium, microorganisms in9kind of cold water fish`s intestine fromIrtysh River Basin of Xinjiang Altay region were isolated. Lactic acid bacteria with low temperaturetolerance were screened out and the optimum growth temperature and physiology biochemistryexperiments were also measured. The phylogenetic status of those Lactic acid bacteria with lowtemperature resistant were identified based on16S rRNA gene sequence. BOX、(GTG)5、ERIC primerswere used to preform the rep-PCR, the strains with highly homologous of16S rRNA were futureinvestigated, A preliminary study on the susceptibility of the isolated strains were also preformed with thepaper method.Results:1. With the MRS, Elliker medium,78bacterial strains with low temperature tolerance were isolated inthis study. Morphological observations showed that among the strains with low temperature tolerance,35Colony morphology are much larger, The colony diameter is greater than5mm;16strains colony diameteris1-5mm;27strains`colony diameter is less than1mm. Moreover, most of the isolated strains were milklywhite, some were faint yellow and a few were white cellophane. Finally,24isolated strains were suspectedas lactic acid bacteria with the Gram stain and catalase experiment.2. Temperature tolerance test show that among the24isolated strains,8were psychrophile and16were psychrotrophs. Physiology biochemistry experiments and homologous of16S rRNA were preformedto invastaged those strains: the24isolated strains belonged to6categories, Among them,3belonged toCarnobacterium,9belonged to Lactococcus,7to Enterococcus,2to Weissella,2to Streptococcus, and1toBrochothrix.3. Many stripes of fingerprint were observed in Lactic acid bacteria by BOX-PCR、ERIC-PCR、(GTG)5-PCR Fingerprinting. The variety of the stripes showed the difference of strains in genetic level.As showed in the Fingerprint clustering analys is, all the strains could be diveded into6groups on thesimilarity level of70%. The genetic difference between Lactococcus and Enterococcus were also clearlydemonstrated,4species were belonged to Lactococcus while2belonged to Enterococcus4.24strains of Lactic acid bacteria with low temperature tolerance were isolated and indentified fromdifferent kinds of cold water fish. The testing results of11kinds commonly used antibiotics showed that streptomycin had the highest drug resistance rate(100%); AMP had the highest antibiotic sensitiverate(100%); penicillin had the highest mediation rate(83.33%); In addition, Different strains of Lactic acidbacteria have different drug sensitivity...