Detection of IncP replicon-specific regions in DNA from Antarctic microbiota

Plasmids capable of horizontal transfer contribute to the adaptability of bacteria, as they may provide genes that enable their hosts to cope with different selective pressures. Only limited information is available on plasmids from Antarctic habitats, and up until now surveys have only used traditional methods of endogenous plasmid isolation. The method based on primer systems, designed on the basis of published sequences for plasmids from different incompatibility (Inc) groups, is appropriate to detect the replicon-specific regions of corresponding plasmids in cultured bacteria, or in total community DNA, which share sufficient DNA similarity with reference plasmids at the amplified regions. In this study, we applied broad-host-range plasmid-specific primers to DNA from microbial samples collected at six different locations in Northern Victoria Land (Antarctica). DNA preparations were used as targets for PCR (polymerase chain reaction) amplification with primers for the IncP (trfA2) and IncQ (oriV) groups. PCR products were Southern blotted and hybridized with PCR-derived probes for trfA2 and oriV regions. This approach detected the occurrence of IncP-specific sequences in eight out of fifteen DNA samples, suggesting a gene-mobilizing capacity within the original habitats.