Influence of soil variables on in situ plasmid transfer from Escherichia coli to Rhizobium fredii.

A. Richaume, J. S. Angle, M. J. Sadowsky

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


A model system was established to determine whether intergeneric plasmid transfer occurs in soil and how various soil variables affect the rate of plasmid transfer. The donor bacterium, Escherichia coli HB101 carrying plasmid pBLK1-2 (pRK2073::Tn5), and the recipient bacterium, Rhizobium fredii USDA 201, were inoculated into a sterile Adelphia fine-sandy-loam soil. Transconjugants were enumerated by direct plating on antibiotic-amended HM [N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid; 2-(N-morpholino) ethanesulfonic acid] salts medium. Randomly chosen transconjugants were verified by serological typing and Southern hybridization with a Tn5 gene probe. The maximum transfer frequency was observed after 5 days of incubation (1.8 x 10(-4) per recipient). The influences of clay (0 to 50% addition), organic matter (0 to 15% addition), soil pH (4.3 to 7.25), soil moisture (2 to 40%), and soil incubation temperature (5 to 40 degrees C) on plasmid transfer were examined. Maximum transfer frequencies were noted at a clay addition of 15%, an organic matter addition of 5%, a soil pH of 7.25, a soil moisture content of 8%, and a soil incubation temperature of 28 degrees C. These results indicate that intergeneric plasmid transfer may occur in soil and that soil variables may significantly affect the rate of transfer.

Original languageEnglish (US)
Pages (from-to)1730-1734
Number of pages5
JournalApplied and environmental microbiology
Issue number7
StatePublished - Jul 1989

Fingerprint Dive into the research topics of 'Influence of soil variables on in situ plasmid transfer from Escherichia coli to Rhizobium fredii.'. Together they form a unique fingerprint.

Cite this