Studies On Plasmid PBL29 Of Bacillus Licheniformis 29

The presence of plasmid in Bacillus was isolated by improved alkalinelysis. Only one plasmid pBL29 was detected in Bacillus Iicheniformis29. Puried and identified by gel electrophoresis,the plasmid pBL29 is cccDNA and the molecular weight of the plasmid pBL29 was estimated to be about 3.7Kb. The sensitivity of Bacillus Iicheniformis29 to 18 antibiotics was determined by inhibitory zone with filter paper. The result proved that Bacillus Iicheniformis29 were resistant to Km and sensitive to the other antibiotics. The elimination of plasmid by acridine orange or by SDS and the transformation of protoplast indicated that Km resistance genes are located on the plasmid pBL29,not on the chromosome. The character of the plasmid is it's many unique restriction endonucleases sites,such as EcoR I ,Sma I > HindllJ x Bgl II Pst I ,Xba I and BamHI et.al. The restriction map of the plasmid pBL29 was tentatively constructed according as the molecular weights of fragments of plasmid pBL29 digested with different enzymes.Analysing the sequence of the plasmid pBL29 tested ,we found that the molecular weight of the plasmid pBL29 is 371 lbp,that it s many unique restriction endonucleases,Km resistance genes and abundant A/T base pairs of replicating site are on the plasmid pBL29.