Underestimation of Bacterial Numbers in Starvation-survival Mode Using the Nucleic Acid Stain DAPI
Archiv fur Hydrobiologie
bacteria enumeration, staining technique, biofilm, starvation conditions
The DAPI (4′,6-diamidino-2-phenylindole) staining method is widely used to enumerate environmental bacteria. In this study, we provide evidence that the conventional DAPI method underestimates bacterial numbers under starvation conditions. In a study of bacteria from biofilms on decomposing maple leaves, treatment of cells with HCl increased the number of bacteria that were visible using DAPI. Laboratory experiments demonstrated induction of an underestimation of bacterial numbers using DAPI by placing a common stream bacterium, Burkholderia cepacia, in carbon limited medium. Although the mechanism by which HCl treatment caused increased visibility of cells is unknown, we suggest that production of DNA-binding, stress induced proteins may be responsible for the inability to stain some cells with DAPI.
Mcnamara, Christopher J.; Lemke, Michael J.; and Leff, Laura G. (2003). Underestimation of Bacterial Numbers in Starvation-survival Mode Using the Nucleic Acid Stain DAPI. Archiv fur Hydrobiologie 157(3), 309-319. doi: 0.1127/0003-9136/2003/0157-0309 Retrieved from http://digitalcommons.kent.edu/bscipubs/112