Estimations of the bacterial content of air can be more easily made now than a decade ago, with colony formation the method of choice for enumeration of airborne bacteria.
However, plate counts are subject to error because bacteria exposed to the air may remain viable yet lose the ability to form colonies, i.e., they become viable but nonculturable.
If airborne bacteria exhibit this phenomenon, colony formation data will significantly underestimate the bacterial populations in air samples.
The objective of the study reported here was to determine the effect of aerosolization on viability and colony-forming ability of Serratia marcescens, Klebsiella planticola, and Cytophaga allerginae.
A collison nebulizer was used to spray bacterial suspensions into an aerosol chamber, after which duplicate samples were collected in all-glass impingers over a 4-h period.
Humidity was maintained at ca.
20 to 25%, and temperature was maintained at 20 to 22°C for each of two replicate trials per microorganism.
Viability was determined by using a modified direct viable count method, employing nalidixic acid or aztreonam and p-iodonitrotetrazolium violet (INT).
Cells were stained with acridine orange and observed by epifluorescence microscopy to enumerate total and viable cells.
Viable cells were defined as those elongating in the presence of antibiotic and/or reducing INT.
CFU were determined by plating on tryptic soy agar and R2A agar. (...)
Mots-clés Pascal : Bactérie Gram négatif, Serratia marcescens, Enterobacteriaceae, Bactérie, Aérosol, Viabilité, Colonie, Dénombrement, Méthode, Culture microorganisme, Pollution intérieur, Pollution air, Cytophagaceae, Cytophagales, Klebsiella planticola, Cytophaga allerginae, Culturabilité
Mots-clés Pascal anglais : Gram negative bacteria, Serratia marcescens, Enterobacteriaceae, Bacteria, Aerosols, Viability, Colony, Enumeration(counting), Method, Microorganism culture, Indoor pollution, Air pollution, Cytophagaceae, Cytophagales
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 97-0487270
Code Inist : 002A05B14. Création : 03/02/1998.