Use of enzymatic methods for rapid enumeration of coliforms in freshwaters.
Rapid enumeration methods based on the enzymatic hydrolysis of 4-methylumbelliferyl-beta-D-galactoside and 4-methylumbelliferyl-beta-D-glucuronide were optimized for freshwaters. The enzymes beta-D-galactosidase (GALase) and beta-D-glucuronidase (GLUase) were shown to be already induced in freshwaters when tested, respectively, with the inducers isopropyl-beta-D-thiogalactopyranoside and methyl-beta-D-glucuronide. Both enzymatic activities were compared, respectively, with plate counts of total and faecal coliforms in freshwaters. Enzymatic methods and reference plate counts were significantly correlated in log-log plots. Moreover, the GLUase method allowed the detection of viable (presenting a detectable GLUase activity) but nonculturable Escherichia coli.
George
I
I
Groupe de Microbiologie des Milieux Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, Bruxelles, Belgium. igeorge@ulb.ac.be
Petit
M
M
Servais
P
P
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000254:growth & development* / Q000302:isolation & purification; D004790:Enzyme Induction; D005243:Feces / Q000382:microbiology; D005618:Fresh Water / Q000382:microbiology*; D005966:Glucuronidase / Q000378:metabolism*; D014871:Water Microbiology; D001616:beta-Galactosidase / Q000378:metabolism*
D001616:beta-Galactosidase; D005966:Glucuronidase