Toward absolute viability measurements for bacteria

Document Type

Article

Publication Date

12-1-2021

Abstract

We aim to develop a quantitative viability method that distinguishes individual quiescent from dead cells and is measured in time (ns) as a referenceable, comparable quantity. We demonstrate that fluorescence lifetime imaging of an anionic, fluorescent membrane voltage probe fulfills these requirements for Streptococcus mutans. A random forest machine-learning model assesses whether individual S. mutans can be correctly classified into their original populations: stationary phase (quiescent), heat killed and inactivated via chemical fixation. We compare the results to intensity using three models: lifetime variables (τ1, τ2 and p1), phasor variables (G, S) or all five variables, with the five variable models having the most accurate classification. This initial work affirms the potential for using fluorescence lifetime of a membrane voltage probe as a viability marker for quiescent bacteria, and future efforts on other bacterial species and fluorophores will help refine this approach.

Publication Title

Journal of Biophotonics

Volume

14

Issue

12

Digital Object Identifier (DOI)

10.1002/jbio.202100175

ISSN

1864063X

E-ISSN

18640648

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