Comparative biology of IncQ and IncQ-like plasmids

Plasmids belonging to Escherichia coli incompatibility group Q are relative ly small (approximately 5 to 15 kb) and able to replicate in a remarkably b road range of bacterial hosts. These include gram-positive bacteria such as Brevibacterium and Mycobacterium and gramnegative bacteria such as Agrobac terium, Desulfovibrio, and cyanobacteria. These plasmids are mobilized by s everal self-transmissible plasmids into an even more diverse range of organ isms including yeasts, plants, and animal cells. IncQ plasmids are thus hig hly promiscuous. Recently, several IncQ-like plasmids have been isolated fr om bacteria found in environments as diverse as piggery manure and highly a cidic commercial mineral biooxidation plants. These IncQ-like plasmids belo ng to different incompatibility groups but have similar broad-host-range re plicons and mobilization properties to the IncQ plasmids. This review cover s the ecology, classification, and evolution of IncQ and IncQ-like plasmids .