Probiotic Properties Of Weissella Strains Isolated From Giant Panda Faeces And Pickles

ObjectiveTo isolate and identify Weissella strains from giant panda faeces and Hunan pickles,and analysis the probiotic properties of these Weissella strains.Materials and Methods(1) Weissella strains were identified based on their colonial morphology,physiologyical and biochemical experiments and 16 S rDNA gene sequences. The probiotic properties of these weissella strains was evaluated by the acid and bile acid resistance, the?-glucosidase activiyt assayes.(2) The ?-glucosidase gene of weissella strains was cloned by PCR. The amplified fragment was extracted from an agarose gel by using a gel extraction kit and ligated with pET22 b. Escherichia coli DH5? competent cells were transformed with the ligation mixture and then E.coli BL21 cells were transformed with the obtained recombinant plasmid. IPTG was added to induce the expression of recombinant enzyme and its enzyme activity were measured. The inclusion bodies expressed in E.coli BL21 were purified and renatured.(3)Plasmids were extracted from weissella strains and determined by double digestion. Fragments were analyzed after gene sequencing.Results(1) One W. cibaria strain was isolated from giant panda faeces and four W. confuse strains were isolated from Hunan pickles. All of five strains could ferment cellobiose.Five Weissella strains could grow well under the condition of pH 3.0; W.confuse QJ013 and HH053 were quite resistant against 0.2 % bile salt.(2) A gene encoding ?-glucosidase was cloned from W. cibaria and overexpressed in E.coli BL21. The result of BLAST showed that this ?-glucosidase shared 93 % DNA sequence identity with W. cibaria strain 37.(3) A cryptic plasmid isolated from W. confusa QJ012, designated p QJ012, was sequenced and characterized. It is a 1489 bp circular molecule with a G+C content of42.8%.The result of BLAST showed that pQJ012 was closely related to pJY33(93 %)?pKLCA(92 %). ORF1 encoded a 282 amino acid residue Rep protein which was 91 %identical to pJY33 and 85 % identical to pKLCA.ConclusionFive Weissella strains were isolated in this paper, and for the first time W. cibaria was isolated from giant panda faeces. A gene of encoding ?- glucosidase was cloned from W. cibaria and overexpressed in E.coli BL21,which revealed that Weissella strains may be involved in the digestion of cellulose in host body. A cryptic plasmid isolated from W. confusa QJ012 was sequenced and characterized. Sequence analysis indicated that plasmid pQJ012 belongs to pT181 family, a member of rolling-circle replication(RCR). The plasmid didn't code probiotic properties of functional protein.