DAO prepress abstract  -  doi: 10.3354/dao01919

ABSTRACT: Batrachochytrium dendrobatidis, an aquatic amphibian fungus, has been implicated in many amphibian declines and extinctions. A real-time polymerase chain reaction (PCR) TaqMan assay is now used to detect and quantify B. dendrobatidis on amphibians and other substrates via tissue samples, swabbing and filtration. The extreme sensitivity of this diagnostic test makes it necessary to rigorously avoid cross-contamination of samples, which can produce false positives. One technique used to eliminate contamination is to destroy the contaminating DNA by chemical means. We tested three concentrations of sodium hypochlorite (NaOCl) (1%, 6%, 12%) over four time periods (1, 6, 15 and 24 h) to determine if NaOCl denatures B. dendrobatidis DNA sufficiently to prevent its recognition and amplification in PCR tests for the fungus. Soaking in 12% NaOCl denatured 100% of DNA within an hour. 6% NaOCl was on average 99.999% effective across all exposure periods, with only very low numbers of zoospores detected following treatment. 1% NaOCl was ineffective across all treatment periods. Under ideal, clean, conditions treatment with 6% NaOCl may be sufficient to destroy DNA and prevent cross contamination of samples, however, we recommend treatment with 12% NaOCl for an hour to be confident all B. dendrobatidis DNA is destroyed.