Determination of DNA-DNA Hybridization Condition for Rapid Identification of Mycobacterium Species

ABSTRACT

Rapid identification of Mycobacterium spp. isolated from patients is important with increased isolation of mycobacteria other than tubercle bacilli (MOTT). DNA-DNA hybridization with streptavidin-peroxidase and tetramethylbenzidine (TMB) color reaction method was recognized as a useful tool for identification of various species of mycobacteria. In this study, optimum condition of the test was determined. The optimal concentrations of tetramethylbenzidine dihydrochloride and hydrogen peroxide for streptavidin-horseradish peroxidase were 0.3-0.6 ug/ ml and 0.16 mM, respectively. The TMB stock solution was stable when prepared in methanol and the dilution of TBM stock solution in 10 mM sodium citrate-10 mM EDTA solution (pH 5.0) gave highest peroxidase-TMB activity. The suitable composition of hybridization solution consisted of 2 x SSC, 10% dextran sulfate, 50 ug/ml salmon DNA, 5 x Denhardt's solution, and 50% formamide. The 5-minute heating at 100C of test DNA prior to photobiotin labeling significantly increased the reaction. In conclusion, DNA-DNA hybridization method with streptavidin-peroxidase and TMB color reaction method may be useful for rapid identification of Mycobacterium spp. isolated from patients.