Use of DEAE-cellulose filters in the S1 nuclease method for bacterial deoxyribonucleic acid hybridization

Polynucleotide sequence relatedness can be studied with the S1 nuclease method by a fast and accurate procedure using DEAE-cellulose filters (DE81 Whatman). After S1 treatment of DNA-DNA hybrid molecules formed in 0.42 M saline solution, free nucleotides (digestion products) but not DNA are eluted from DE81 filters in appropriate salt concentration such as 5% Na2HPO4.12 H2O. The relative binding ratio and the thermal stability of heteroduplexes are determined for 7 strains of Enterobacteriaceae. The conclusions resulting from S1 nuclease and DE81 filters assay are similar to those obtained with S1 nuclease and trichloracetic acid precipitation.