As far as bacterial species determination is concerned, although not very widely used, DNA-DNA hybridization is considered to be a cornerstone. In addition to the16S rRNA gene sequencing, which have been a reliable aid to the identification of diverse bacteria in the past decades. 

DNA-DNA hybridization is one method that provides more resolution than 16S rDNA sequencing, and the 70% criterion has been a cornerstone for describing a bacterial species. In spite of these values, the method is not popular. Major disadvantages are the laborious nature of pairwise cross-hybridizations, the requirement for isotope use, and the impossibility of establishing a central database.

regards

Rathish

Dear Rathish Nair

  Thanks for replaying. I think 16S rDNA sequencing method still  easier to perform although it needs for more public universal primer to scan as more as possible of bacterial species. Thanks again.