With the rapid development of microbiological analysis in recent years, the question arises as to what the future of drinking water monitoring for microbiological parameters will look like.
Routine and accredited monitoring of the microbiological-hygienic quality of drinking, industrial and bathing water is carried out using culture-based standard methods. They represent the gold standard of microbiological water quality analysis. However, many advanced questions in the water sector cannot be adequately answered by these standard methods alone. Over the last few decades, the possibilities offered by cultivation-free molecular diagnostics have allowed many issues in microbiological water analysis to be addressed that were unsolvable just a few years ago.
These molecular diagnostic tools for microbiological surveillance have been evaluated in the MoVe project. Overall, a comprehensive overview of these novel methods is given, including nucleic acid-based amplification methods, flow cytometry, sequencing approaches, spectroscopic methods and online sensor technology. Based on the available literature and our own experience, we were able to identify areas of application where the use of certain methods already provides significant added value:
- PCR-based quantitative detection of pathogens such as Legionella or enteric viruses and antibiotic resistance genes.
- Next-generation sequencing to elucidate pathogens, the structure and function of microbial communities and the complete set of antibiotic resistance genes (resistome).
- Flow cytometry for rapid determination of bacterial concentrations and certain characteristics of these bacteria (live/dead and high/low nucleic acid content).
- On-line systems for biomass determination by measuring enzyme activity, ATP content or flow cytometric bacterial enumeration.
- Identification of faecal input sources by PCR-based methods to detect host-specific microbial source tracking markers.
- Identification of bacterial isolates by MALDI-TOF-MS.
- PCR-based detection of metabolic services such as degradation of organic pollutants (raw water protection), nitrification (ammonium oxidation) and denitrification (nitrate reduction) or formation of algal toxins.
The application of new, complementary microbiological, biochemical and molecular biological analysis methods in the drinking water sector is still in its infancy. Close cooperation between the water industry, DVGW institutes and university research is necessary to make adequate use of these new possibilities. It hast o be considered that each method has its strengths and weaknesses. There are no generally valid investigation methods, only suitable tools for clearly defined questions. However, using data from the new methods is also a challenge. The new methods provide concentrations and units that require a new way of thinking. Due to the lack of standardisation, the results need to be interpreted by methodologically experienced experts. Nevertheless, these new methods can provide additional information that can help to clarify important microbiological water quality issues.
Publications:
Fischeder, R., Böckelmann, U., Gerten, B., Gröbe, K., Hambsch, B., Kilb, B., Lange, B., Meyer, J., Soltwisch, A., Schneider, S., Schumacher, V.: Anforderungen an die mikrobiologisch-hygienische Trinkwasseruntersuchung: neue Verfahren. DVGW energie|wasser-praxis 67, Nr.2, S. 32-38 (2016).
Ho, J., Tiehm, A.: Durchflusszytometrie für das mikrobiologische Monitoring In: Zukunftsthemen der Wasserversorgung. 24. TZW-Kolloquium Veröffentlichungen aus dem Technologiezentrum Wasser, ISSN 1434-5765, TZW-Band 90: 81-96 (2019)
Ho, J.; Tiehm, A.; Nocker, A.; Bendinger, B.; West, S.; Trimbach, A.: Durchflusszytometrie als schnelle Detektionsmethode für Bakterien in Roh- und Trinkwasser. DVGW energie | wasser-praxis (EWP) 1/2020: 56-59 (2020)
Hügler, M., Stange, C., Ho, J., Hambsch, B., Tiehm, A.: Molekularbiologische Methoden – Trends und Entwicklungen. In: Entwicklungstrends für die Wasserversorgung. 22. TZW-Kolloquium, Veröffentlichungen aus dem Technologiezentrum Wasser Karlsruhe, ISSN 1434-5765, Band 80: 45-63 (2017)
Hügler, M.: Einsatz des MALDI-TOF zur Identifizierung von Krankheitserregern und Indikatorbakterien. In: Veröffentlichungen aus dem Technologiezentrum Wasser Karlsruhe. 27. TZW Kolloquium. Anpassungsstrategien und Handlungsoptionen für die Wasserbranche. S. 31-45 (2022)
Hügler, M.; Leister, C.; Hambsch, B.: Einsatz der MALDI-TOF-Massenspektroskopie zur Bakterien-Identifizierung in der Trinkwasser-Mikrobiologie. DVGW energie/wasser-praxis 73(12):52-59 (2022)
Stange, C.: Microbial Source Tracking – Identifizierung fäkaler Eintragsquellen. Veröffentlichungen aus dem Technologiezentrum Wasser, ISSN 1434-5765, TZW-Band 99 (2021)
The volumes of the TZW publications can be ordered here.
