Ethidium and propidium monoazide: comparison of potential toxicity on Vibrio sp. viability

• Published in: Letters in applied microbiology Vol. 72; no. 3; pp. 245 - 250
• Main Authors: Copin, S., Mougin, J., Raguenet, V., Robert‐Pillot, A., Midelet, G., Grard, T., Bonnin‐Jusserand, M.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.03.2021
• Subjects: Anti-Bacterial Agents - pharmacology; Aquaculture; Aquatic ecosystems; Azides - pharmacology; Bacteria; Deoxyribonucleic acid; DNA; Ecosystem; EMA; Enumeration; Environmental conditions; Gastroenteritis; Gastroenteritis - microbiology; Gastroenteritis - prevention & control; Humans; Ingestion; Lethal effects; Life Sciences; Microbial Sensitivity Tests; Microbial Viability - drug effects; PMA; Pretreatment; Propidium - analogs & derivatives; Propidium - pharmacology; Real-Time Polymerase Chain Reaction - methods; Seafood; Toxicity; Toxicity testing; VBNC; Viability; Vibrio; Vibrio cholerae - drug effects; Vibrio vulnificus - drug effects; Vibriosis; Water Microbiology; Waterborne diseases; toxicity; EMA; VBNC; PMA; Vibrio
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/lam.13412

Vibrio sp., ubiquitous in the aquatic ecosystem, are bacteria of interest because of their involvement in human health, causing gastroenteritis after ingestion of seafood, as well as their role in vibriosis leading to severe losses in aquaculture production. Their ability to enter a viable but non‐culturable (VBNC) state under stressful environmental conditions may lead to underestimation of the Vibrio population by traditional microbiological enumeration methods. As a result, using molecular methods in combination with EMA or PMA allows the detection of viable (VBNC and culturable viable) cells. In this study, the impact of the EMA and PMA was tested at different concentrations on the viability of several Vibrio species. We compared the toxicity of these two DNA‐binding dyes to determine the best pretreatment to use with qPCR to discriminate between viable and dead Vibrio cells. Our results showed that EMA displayed lethal effects for each strain of V. cholerae and V. vulnificus tested. In contrast, the concentrations of PMA tested had no toxic effect on the viability of Vibrio cells studied. These results may help to achieve optimal PMA‐qPCR methods to detect viable Vibrio sp. cells in food and environmental samples. Significance and Impact of the Study: Ethidium monoazide (EMA) and propidium monoazide (PMA) treatment have commonly been used combined with qPCR to discriminate viable and dead cells. However, these DNA‐binding dyes can damage membranes in viable bacteria, generating false‐negative results. Most available studies examined either EMA‐qPCR or PMA‐qPCR, based on the literature to select the dye of interest. However, none of them tested the cytotoxicity of EMA vs PMA on various Vibrio sp. strains. In this study, we showed that PMA was the optimal dye for Vibrio as a tool for pretreatment when using qPCR methods to determine Vibrio viability in environmental or seafood samples.