Genetic diversity of Bacillus thuringiensis serovars revealed by RFLP using random DNA probes

EcoRI and HindIII restriction fragment length polymorphism (RFLP) profiles using 2 random DNA probes, named 104 and 106, were generated for 85 B. thuringiensis strains. These include 80 serovars, 4 intra-serovar strains: kurstaki HD-1, dendrolimus, tenebrionis and sandiego, and a non-serotypeable strain B. thuringiensis var. wuhanensis. A total of 47 EcoRI and 65 HindIII restriction patterns were generated when hybridization results from both probes were combined. Seventy-seven B. thuringiensis strains showed distinctive hybridization profiles. The dendrogram resulting from the numerical analysis of the distance matrix revealed fourteen distinct phylogenetic groups at the 96% banding patterns similarity. The intra-serovar strains showed higher similarity with their respective type serovars. However, different serovars from a common H-serotype did not always cluster in the same phylogenetic group. Alternatively, several mosquitocidal serovars clustered in a single phylogenetic group. The correlation between serotyping and banding pattern similarity is discussed.