AMPLIFICATION OF BACTERIAL-DNA BOUND ON CLAY-MINERALS BY THE RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) TECHNIQUE

Chromosomal DNA from Bacillus subtilis, bound on the clay minerals, mo ntmorillonite (Wyoming (W) and Apache County (Ap)) and kaolinite (K), was subjected to the random amplified polymorphic DNA (RAPD) technique . DNA bound on the claps was not amplified with 0.625, 1.875, 6.25, an d 12.5 U of Taq DNA polymerase, but amplification occurred when the cl ay-DNA complexes were diluted 10- and 20-fold or when 21 U of Taq DNA polymerase was added. DNA desorbed from the Ap-DNA and K-DNA equilibri um complexes was amplified with 0.625 U of Taq DNA polymerase, whereas amplification of DNA desorbed from the W-DNA complex occurred only af ter a 10-fold dilution or when 1.875 U of Taq DNA polymerase was used. These observations indicate that clay minerals differentially affect the amplification process, probably by inhibiting the activity of Taq DNA polymerase.