microLAN B.V.  - Aqualabo Group

Robust on-line monitoring assay - Case Study


Courtesy of microLAN B.V. - Aqualabo Group

Alkaline Phosphatase Enzyme Activity Measurement as a Robust on-line Monitoring Assay for Water Quality Assessment.

Zina Al-Saar 4th year Intern student Avans University of Applied Science - ATGM Department Joep Appels - Supervisor and Managing Director microLAN on line Bio-monitoring System.

Many heterotrophic microorganisms maintain their growth by producing enzymes in order to provide low molecular weight inorganic compounds. These compounds could be up taken into the cells from high molecular weight organic compounds which cannot be directly utilized by bacteria. Microbial enzymes are, therefore, directly related to the concentrations and ratios of limiting nutrients, and may be sensitive indicators of organic pollution in aquatic environments. The objective of this study, which was carried at microLAN company in Waalwijk and supported by HWL (Het Water Laboratorium - Haarlem), is to validate the results obtained from the BACTcontrol biosensor by comparing the ALP activity with different common water analysis that are regularly used to assess water quality.

Research Steps

  • Water samples collection: Tap water, Natural Fresh water, Industrial water
  • Analyze samples and assess water quality using BACTcontrol, free and bounded ATP, Total FCM cells count, microscopic TCC count, microscopic ELF-labeled cells counts and Heterotrophic plate count (HPC).
  • Compare results obtained from FCM, ATP, microscopic TCC, microscopic ELF-labeled cells count and HPC and calculate the correlation between BACTcontrole enzyme activity measurements and different approved laboratorial assays.


There were significant correlations between ALP enzyme activity level measured with the BACTcontrol biosensor and with the different cultural-independent biological parameters: (1) total life FCM cell concentration, (2) ATP, (3) total microscopic cell concentration and (3) total microscopic ELF- labelled cells count, when measured between similar water types. These correlations where high between industrial water and tap water, but varied and dropped down when surface water was measured – most likely due to the different biological activity and nutrient availability.

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