A quantitative bacterial dot method for DNA-DNA hybridization and its correlation to the hydroxyapatite method

A filter hybridization method employing bacterial samples and ¹²⁵I]labeled chromosomal DNA as a probe was used for DNA-DNA hybridization. It was found that the hybrids had a thermal melting temperature very similar to that of duplexes formed by purified filterbound DNA. The difference in thermal denaturation midpoint between homologous and heterologous duplexes was determined for a number of strains ofAcinetobacter spp. andEnterobacter agglomerans. A comparison with the corresponding data obtained by the hydroxyapatite method showed good correlation between the two methods. The use of bacterial samples in filter hybridization omits the time-consuming DNA preparation procedure necessary for traditional DNA-DNA hybridization procedures. A simplified, two-step elution procedure is suggested for processing large numbers of strains.