Suppression of environmental DNA degradation in water samples associated with different storage temperature and period using benzalkonium chloride

Environmental DNA (eDNA) is a useful tool for biological monitoring of a target species by detecting DNA contained in environmental samples. However, the suppression of eDNA degradation after sample collection is a major issue when estimating the presence of a target species. Recently, benzalkonium chloride (BAC) was shown to dramatically suppress the degradation of eDNA in fish species from freshwater environments. However, the effect of this inexpensive reagent has not yet been tested in the other fish and shellfish species. We examined changes in eDNA concentrations for three target species (Corbicula japonica,Lateolabrax japonicus, andAnguilla japonica). eDNA was measured in samples containing added BAC. The effects of storage temperature (25 degrees C, 4 degrees C, and -30 degrees C) and storage periods (periods up to 21 d) were also measured to determine how sample degradation was affected. We observed that BAC addition was effective in suppressing eDNA degradation, and its influence was similar among species but not storage temperatures. The concentrations of eDNA with BAC for all three species did not decrease with storage period, except forL. japonicusat 25 degrees C and 4 degrees C. Our results suggest that BAC affects eDNA degradation universally for a variety of species inhabiting both freshwater and brackish water.