Endogenous isolation of replicon probes for assessing plasmid ecology of marine sediment microbial communities.

Six functional replication origins (repGA14, repGA33, repGA70, repSD41, repSD164 and repSD172), obtained from endogenously isolated, broad-host-range (BHR) marine plasmids ranging in size from 5 to 60 kb, were used to determine plasmid occurrence in three coastal marine sediment sites (in California, Georgia and South Carolina, USA). The plasmid-specific replicons were isolated from plasmid-bearing marine sediment bacteria belonging to the alpha and gamma subclasses of the Proteobacteria. The plasmid sources of the endogenous replicons were considered to be cryptic due to a lack of identifiable phenotypic traits.