“…We do not regard the discovery of homologous replicons in Staphylococcus, Streptococcus, and Bacillus species as very surprising in itself, since these genera have long been recognized to include members with natural mechanisms for efficient uptake of and transformation by both chromosomal and plasmid DNAs (9,12,17,19,20,27,28). Recent reports of conjugative plasmids in these bacteria that transfer across genus barriers, as well as species barriers (4,10,16,23), further strengthen the conclusion that intergeneric exchange of genetic material in their natural environments must be relatively common among them. We were surprised, however, by the very high degree of sequence homology between pBC16 and pAMalAl apparent in their restriction fragment fingerprints.…”