Title
Effect of air drying on bacterial viability: A multiparameter viability assessment
Author
Nocker, A.
Fernández, P.S.
Montijn, R.
Schuren, F.
Publication year
2012
Abstract
The effect of desiccation on the viability of microorganisms is a question of great interest for a variety of public health questions and industrial applications. Although viability is traditionally assessed by plate counts, cultivation-independent methods are increasingly applied with the aim to gain more insight into why cells might not form colonies and to optimize production processes. To evaluate their usefulness, we applied in this study a multiparameter viability assay to selected bacteria (Escherichia coli, Pseudomonas aeruginosa, Enterococcus hirae, and Staphylococcus aureus) subjected to air-drying in the absence or presence of supplements. Tests included growth on solid culture medium and the measurement of membrane integrity, membrane potential, esterase and respiratory activities using fluorescent dyes. All measured parameters were responsive to desiccation stress. Results suggested that extending plate count analysis with cultivation-independent methods can greatly enhance resolution especially for moderate stress conditions, which do not get reflected in plate counts due to cellular recovery. Whereas plate counts reflect the final effect on viability, immediate measurement of cellular functions provides a snapshot picture of the fitness status at a specific point in time. Special emphasis was given to MgCl 2 which in concentrations≥50mM dramatically increased the bacterial susceptibility to desiccation in the case of the gram-negative bacteria and to a lesser extent also for the gram-positive bacteria. The study in addition confirmed a good agreement of results obtained with the recently developed real-time viability (RTV) assay and the BacLight LIVE/DEAD method in combination with a fluorescence plate reader. © 2012 Elsevier B.V.
Subject
Life
MSB - Microbiology and Systems Biology
EELS - Earth, Environmental and Life Sciences
Healthy for Life
Biology
Healthy Living
Desiccation
Extracellular polysaccharides
Freeze drying
Magnesium chloride
Real time viability (RTV) assay
Viability
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http://resolver.tudelft.nl/uuid:03cbc3f7-3f1e-4d3b-84c3-3bbc91630884
DOI
https://doi.org/10.1016/j.mimet.2012.04.015
TNO identifier
460769
ISSN
0167-7012
Source
Journal of Microbiological Methods, 90 (2), 86-95
Document type
article