ABSTRACT
Objective To knockout and identify the Antigen 43 (Ag43) in the Escherichia Coli JM109 .Methods Mutation group Ⅱ introns RNA protein complexes (RNP) gene sequence was obtained by Sigma Company′s TargeTron Gene Knockout Sys‐tem and Ag43 gene specific designed PCR primers amplification ,then ,to acquired Ag43 specific recombinant RNP plasmid pACD4K‐Ag4 ,this gene sequence was inserted into the plasmid pACD4K‐C of RNA′s expression .Finally ,pEGFP‐Ag43 was trans‐formed into JM109 and inserted the group Ⅱ intron into the Ag43′s locus by IPTG inducing expression .Results The best insertion locus was between 1 812 and 1 913 .Through the agarose electrophoresis gel ,the RNP gene sequence was consistent with the expec‐ted value (350 bp) .The pEGFP‐Ag43 vector was correctly constructed which was proofed by endonuclease Nhe Ⅰ and Hind ⅡI di‐gestion as predicted products (3 646 and 4 029 bp;7 000 and 550 bp ,respectively ) .The PCR and gene sequence results indicated that the group Ⅱ intron was inserted into the locus between 1 812 and 1 913 in the Ag43 gene .Conclusion Successful knockout of the Ag43 in Escherichia Coli JM109 found basis to further study the Ag43′s function and regard the coli as host bacteria of Ag43 chimeric protein recombinant .
ABSTRACT
OBJECTIVE@#To analysis and identify a bacterium strain isolated from laboratory breeding mouse far away from a hospital.@*METHODS@#Phenotype of the isolate was investigated by conventional microbiological methods, including Gram-staining, colony morphology, tests for haemolysis, catalase, coagulase, and antimicrobial susceptibility test. The mecA and 16S rRNA genes were amplified by the polymerase chain reaction (PCR) and sequenced. The base sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank database by phylogenetic analysis and multiple sequence alignment.@*RESULTS@#The isolate in this study was a gram positive, coagulase negative, and catalase positive coccus. The isolate was resistant to oxacillin, methicillin, penicillin, ampicillin, cefazolin, ciprofloxacin erythromycin, et al. PCR results indicated that the isolate was mecA gene positive and its 16S rRNA was 1 465 bp. Phylogenetic analysis of the resultant 16S rRNA indicated the isolate belonged to genus Saphylococcus, and multiple sequence alignment showed that the isolate was Saphylococcus haemolyticus with only one base difference from the corresponding 16S rRNA deposited in the GenBank.@*CONCLUSIONS@#16S rRNA gene sequencing is a suitable technique for non-specialist researchers. Laboratory animals are possible sources of lethal pathogens, and researchers must adapt protective measures when they manipulate animals.