Plasmids in carboxydotrophic bacteria: physical and restriction analysis

Abstract

Twenty species and strains of aerobic CO-oxidizing bacteria were screened for the occurrence of plasmids. Six of them harbored plasmids between 45 and 558kb. Megaplasmids of 428 and 558 kb were resolved in Alcaligenes carboxydus. Restriction digest patterns of plasmids from different carboxydotrophic bacteria were dissimilar. However, the patterns obtained with the plasmids from the strains OM5, OM4 and OM2 of Pseudomonas carboxydovorans were very much the same. The nine cured mutants of P. carboxydovorans OM5, as well as the deletion mutant OM5-29, could not grow chemolithotrophically with CO or H2 plus CO2, as they were devoid of CO dehydrogenase, hydrogenase and ribulose bisphosphate carboxylase. The deletion mutant OM5-24 retained the ability to grow with CO. It could not grow with H2 plus CO2 and was devoid of H2ase. The data suggest the residence of structural and/or regulatory genes of CODH, H2ase and RuBPCx on plasmid pHCG3 of P. carboxydovorans.