Table 1.

Fluorescent dyes used for detection of VBNC bacteria.

Dye	Mechanism	Reaction
Acridine orange	The staining response depends on the ratio of DNA to protein in the cells	Actively reproducing cells appear green but slow-growing or nonreproducing cells at time of staining appear orange
Di-amino-phenyl-indole (DAPI)	Differential staining	Living cells look green under fluorescent microscope
Indophenyl-nitrophenyl-phenyl tetrazolium chloride (INT)	INT reacts with dehydrogenase enzyme to produce formazone and red color, thus living cells appear red	Living cells appear red.
Fluorescein isothiocyanate (FITC)	Enzyme activity in living cell	FITC stains living cells violet or blue