A sensitive and rapid method to determine the viability of freeze-dried bacterial cells.
OBJECTIVE
To determine the potential use of flow cytometry for viability asssessment of freeze-dried bacterial cells.


RESULTS
Escherichia coli CIP 54.8T and Vibrio metschnikovii CIP 104262 were analysed. The viability of freeze-dried cells resuspended in a nutrient broth was evaluated by culture whereas activity was determined by flow cytometry analysis of both esterase activity and cell death. Activity assessment by flow cytometry was found to be a rapid and good indicator of cell viability and was very efficient for quality control. For V. metschnikovii the fraction of active cells varies greatly depending on the freeze-drying procedure and within a given procedure.


CONCLUSIONS
Bacterial activity assessment by flow cytometry is very efficient for the control of freeze-dried cells.
Parthuisot
N
N
Observatoire Océanologique, Université Pierre et Marie Curie, CNRS UMR7621, Institut des Sciences de l'Univers, BP44, F-66651 Banyuls-sur-Mer Cedex, France.
Catala
P
P
Lebaron
P
P
Clermont
D
D
Bizet
C
C
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D003470:Culture Media; D004926:Escherichia coli / Q000166:cytology / Q000254:growth & development*; D005434:Flow Cytometry / Q000379:methods*; D005456:Fluorescent Dyes; D005612:Freeze Drying; D009930:Organic Chemicals; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors; D014733:Vibrio / Q000166:cytology / Q000254:growth & development*
D003470:Culture Media; D005456:Fluorescent Dyes; D009930:Organic Chemicals; C098798:SYBR Green II