Conjugation and genetic recombination in Escherichia coli in sterile and nonsterile soil

Conjugal transfer of chromosomal DNA and genetic recombination in E. coli occurred in both sterile and nonsterile soil, but the frequency of recombination (F.O.R.) was higher in sterile soil. The F.O.R. was increased when the soil was amended with montmorillonitc but not when amended with kaolinite, and both the survival of the parentals and conjugation (i.e. the F.O.R.) increased as the pH of the soil was increased from 4.7 towards neutrality.