@article {2855505,
	title = {Frequency and diversity of small cryptic plasmids in the genus Rahnella},
	journal = {BMC Microbiol},
	volume = {10},
	year = {2010},
	month = {2010 Feb 19},
	pages = {56},
	abstract = {BACKGROUND: Rahnella is a widely distributed genus belonging to the Enterobacteriaceae and frequently present on vegetables. Although Rahnella has interesting agro-economical and industrial properties and several strains possess antibiotic resistances and toxin genes which might spread within microbial communities, little is known about plasmids of this genus. Thus, we isolated a number of Rahnella strains and investigated their complements of small plasmids.

RESULTS: In total 53 strains were investigated and 11 plasmids observed. Seven belonged to the ColE1 family; one was ColE2-like and three shared homology to rolling circle plasmids. One of them belonged to the pC194/pUB110 family and two showed similarity to poorly characterised plasmid groups. The G+C content of two rolling circle plasmids deviated considerably from that of Rahnella, indicating that their usual hosts might belong to other genera. Most ColE1-like plasmids formed a subgroup within the ColE1 family that seems to be fairly specific for Rahnella. Intriguingly, the multimer resolution sites of all ColE1-like plasmids had the same orientation with respect to the origin of replication. This arrangement might be necessary to prevent inappropriate synthesis of a small regulatory RNA that regulates cell division. Although the ColE1-like plasmids did not possess any mobilisation system, they shared large parts with high sequence identity in coding and non-coding regions. In addition, highly homologous regions of plasmids isolated from Rahnella and the chromosomes of Erwinia tasmaniensis and Photorhabdus luminescens could be identified.

CONCLUSIONS: For the genus Rahnella we observed plasmid-containing isolates at a frequency of 19\%, which is in the average range for Enterobacteriaceae. These plasmids belonged to different groups with members of the ColE1-family most frequently found. Regions of striking sequence homology of plasmids and bacterial chromosomes highlight the importance of plasmids for lateral gene transfer (including chromosomal sequences) to distinct genera.},
	keywords = {Bacterial Proteins, Base Sequence, Cloning, Molecular, Gene Transfer, Horizontal, Models, Genetic, Molecular Sequence Data, Multigene Family, Phylogeny, Plasmids, Rahnella, Sequence Alignment, Vegetables},
	issn = {1471-2180},
	doi = {10.1186/1471-2180-10-56},
	author = {Rozhon, Wilfried and Petutschnig, Elena and Khan, Mamoona and Summers, David K and Poppenberger, Brigitte}
}
