Sequencing and characterization of a cryptic plasmid pLP-8 from Lactobacillus plantarum
Volume : 53 Page : 81-89
CY Fang, ZW Chen, JH Lin, SL Hsuan, JP Wang
Lactobacillus plantarum is a lactic acid bacterium widely used as a starter microorganism in vegetable and meat fermentation. Previous studies showed that many L. plantarum strains have one or more native resident plasmids of various sizes. In this study, the smallest cryptic plasmid of L. plantarum ATIT-023 isolated from local pickled cabbage, designated as pLP-8, was sequenced and characterized. Sequencing results showed that pLP-8 consists of 3414 bp with a GC content of 37.73%. Sequence analysis revealed that pLP-8 contains three putative open reading frames (orf1 to orf3) which could encode proteins designated as a replication protein, a hypothetical protein, and a mobilization protein, respectively. A putative double strand origin and a putative single strand origin were predicted upstream of the orf1 (rep). It is suggested that pLP-8 replicates via the rolling-circle replication mechanism. The relative copy number of pLP-8 was estimated to be about 5 in each cell by real-time quantitative PCR. In the near future, the minimal replicon of pLP-8 will be used for construction of a lactic acid bacteria/Escherichia coli shuttle vector which could be applied as a molecular tool for genetic engineering of L. plantarum.