Beta-D-glucuronidase activity assay to assess viable Escherichia coli abundance in freshwaters.
OBJECTIVE
The relationships between the beta-D-glucuronidase (GLUase) activity, the abundance of culturable Escherichia coli and the number of viable E. coli were investigated in river and wastewater samples.


RESULTS
GLUase activity was measured as the rate of hydrolysis of 4-methylumbelliferyl-beta-D-glucuronide. Culturable E. coli were enumerated by the most probale number (MPN) microplate method. Viable E. coli were estimated by fluorescent in situ hybridization (FISH) coupled with a procedure of viability testing (DVC-FISH procedure). Significant correlations were found between the log of GLUase activity and both, the log culturable E. coli and the log of viable E. coli.


CONCLUSIONS
GLUase activity per viable E. coli gave a broadly constant value from low to highly contaminated waters while GLUase activity per culturable E. coli strongly increased at low contaminated waters because of an underestimation of the number of active E. coli by the culture-based method.


CONCLUSIONS
GLUase activity is a reliable parameter for the rapid quantification of viable E. coli in waters.
Garcia-Armisen
T
T
Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, Bruxelles, Belgium.
Lebaron
P
P
Servais
P
P
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D005602:France; D005618:Fresh Water / Q000382:microbiology*; D005966:Glucuronidase / Q000378:metabolism*; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D045483:Rivers / Q000382:microbiology; D014871:Water Microbiology
D006923:Hymecromone; C034888:4-methylumbelliferyl glucuronide; D005966:Glucuronidase