Strains of P. asymbiotica , either from the USA or Australia, are the only Photorhabdus that carry plasmids. Restriction enzyme (Bgl 2) analysis of Pa plasmids confirms the similarity of plasmids in different USA (lanes 1–4) and Australian (lanes 5–7) isolates. Strains are from North America: 1, ATCC43950 (San Antonio, Texas); 2, ATCC43951 (San Antonio, Texas); 3; ATCC43952 (San Antonio, Texas); 4, ATCC43949 (Maryland) and Australia: 5, Beaudesert (Queensland), 6, Murwillumbah (New South Wales) and 7, Gladstone (Queensland). See Gerrard et al. 2004 reference  for more details of Australian strains and their collection.