Abstract: A number of bacteria have been reported to have the capability to enter a viable but nonculturable (VBNC) state as a response to environmental stress. Cell culture techniques often fail to detect bacterial cells in the VBNC state; however, molecular biology methods can improve the detection efficiency for VBNC cells. Among molecular biology methods for detecting bacterial cells in the VBNC state, the detection of specific DNA or mRNA is a common method and a gfp gene encoding green fluorescent protein has been used as an effective marker to examine VBNC state. Recently, a combinatorial method, designated as ethidium monoazide (EMA)-PCR method, has also been established to detect live/dead cells due to the selective penetration of EMA/PMA into dead cells in the presence of live cells. This detection method combined with the selectivity of EMA/PMA and the specificity of PCR is sufficient to detect viable cells and VBNC cells.

Key words: bacteria, viable but nonculturable state, molecular biology, detection technique