Measurement of Low‐level Extracellular Enzyme Activity in Natural Waters Using Fluorigenic Model Substrates

Abstract

Activities of the extracellular enzymes P-D-glucosidase, phosphatase, and leucine aminopeptidase were investigated in unpolluted waters to test the suitability of fluorigenic model substrates for measuring enzyme activities in water samples expected to sustain low levels of activity. The waters tested were surface running waters, shallow groundwaters, and deep groundwaters from water extraction wells. Enzyme activity was detected in all the waters tested, although some of the hydrolytic rates were at the lower limit of current analytical ca ability. Rates varied between 1.1 and 291 nmol/(L. h) for 1-D-glucosidase, between 9.2 and 320 nmol/(L.h) for phosphatase, and between 5.8 and 1560 nmol/(L h) for leucine aminopeptidase. The method thus proved to be suitable for measuring low levels of extracellular enzyme activity in natural waters, but in any case, it is necessary to adapt the technique to the type of water investigated.Zusammenfassung: Um zu uberprufen, ob mit Hilfe fluorigener Modellsubstrate auch Enzymaktivitaten in Wasserproben mit sehr niedriger Aktivitat nachzuweisen sind, wurden fur die drei extrazellularen mikrobiellen Enzyme P-D-Glucosidase, Phosphatase und Leucin-Aminopeptidase sauberes Oberflachenwasser, Grundwasser und Tiefbrunnenwasser aus Trinkwasserbrunnen untersucht. In allen untersuchten Proben konnte enzymatische Aktivitat gemessen werden. Sie war jedoch stellenweise so niedrig, daR beinahe die merjtechnisch erfarjbare untere Grenze erreicht wurde. Fur P-D-Glucosidase wurden Substratumsatze zwischen 1.1 und 291 nmol/(L. h), fur Phosphatase zwischen 9.2 und 320 nmol/(L. h) und fur Leucin-Aminopeptidase Werte zwischen 5.8 und 1560 nmol/(L. h) bestimmt. Das angewandte Merjverfahren eignet sich gut zur Bestimmung niedriger extrazellularer Enzymaktivitaten. Wir empfehlen jedoch dringend die Anpassung der Methode an jede zu untersuchende Wasserprobe. Erst nach diesem Schritt kann das Verfahren fiir den routinemarjigen Einsatz in der Praxis verwendet werden. Acta hydrochim. hydrobiol. 25 (1997) 5 w -0 WILEY-VCH Verlag GmbH, D-69469 Weinheim, 1997 0323-4320/97/05G%0253 $17.50+.50/0 w RE! Acta hydrochim. hydrobiol. 25 (1997) 5 -

High Resolution Analysis of Contaminated Aquifer Sediments and Groundwater—What Can be Learned in Terms of Natural Attenuation?

“…In situ microbial activity was assessed by determining the enzymatic hydrolysis rates of two fluorogenic substrates, i.e., MUF-P (4-methylumbelliferyl phosphate) and MUF-Glc (4-methylumbelliferyl β-D-glucoside) (Freeman et al 1995;Hendel and Marxsen 1997). Enzyme assays of both groundwater and sediment samples were performed in 4 mL Supelco glass vials.…”

Extracellular Enzyme Activity Associated with Degradation of Beech Wood in a Central European Stream

“…2.4.1. -glucosidase -D-glucosidase activity was determined using the fluorigenic model substrate methylumbelliferyl--D-glucoside (MUF-glc), which provides specific bonds for the naturally occurring enzyme to degrade (HENDEL and MARXSEN, 1997). This process is accompanied by the release of the fluorescent compound methylumbelliferone (MUF), the quantification of which provides a measure of extracellular enzyme activity (HOPPE, 1993).…”

“…This method is more sensitive than conventional photometric methods, and has been used previously for measuring enzymatic activities in water and sediment samples (e.g. MEYER-REIL, 1987;MARXSEN and WITZEL, 1991;MÜNSTER, 1992;HENDEL and MARXSEN, 1997), but not for wood.…”

Extracellular Enzyme Activity Associated with Degradation of Beech Wood in a Central European Stream

“…-glucosidase -D-glucosidase activity was determined using the fluorigenic model substrate methylumbelliferyl--D-glucoside (MUF-glc), which provides specific bonds for the naturally occurring enzyme to degrade (HENDEL and MARXSEN, 1997). -glucosidase -D-glucosidase activity was determined using the fluorigenic model substrate methylumbelliferyl--D-glucoside (MUF-glc), which provides specific bonds for the naturally occurring enzyme to degrade (HENDEL and MARXSEN, 1997).…”