PCR-based detection of mycobacteria in biofilms from a drinking water distribution system

A molecular biological method was developed for the selective detection of mycobacteria in biofilms from drinking water systems without requiring time consuming cultivation procedures. A newly designed 16S rDNA targeted oligo nucleotide primer, which is highly specific for the genus Mycobacterium, wa s used for the selective PCR amplification of mycobacteria 16S rDNA fragmen ts. The PCR products were subsequently hybridized with a second mycobacteri al-specific 16S rDNA-targeted probe. This two-step procedure greatly reduce d the probability of false-positive detection of organisms not affiliated t o the genus Mycobacterium. The specificity and sensitivity of the method wa s confirmed with various target and nontarget reference strains, followed b y application in native biofilms from different drinking water distribution systems. The results of this investigation show that mycobacteria could no t be detected when groundwater was used as raw water source, but were frequ ently found in bank-filtered drinking water biofilms. Further PCR experimen ts indicated that these mycobacteria did not belong to the pathogenic or ce rtain facultative pathogenic species of this genus, but were representative s of the environmental mycobacteria. (C) 1998 Elsevier Science B.V. All rig hts reserved.