In the past few years a new and innovative method has been developed to quickly identify microorganisms – MALDI-TOF-MS (matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy). With this technique, the identification of the bacterial species is achieved by analyzing the spectrum of the bacterial proteome after protein ionization and MALDI-TOF-MS analysis.
What can the MALDI-TOF do?
The method is already established in the clinical field and has considerable potential for the drinking water sector. The great advantage is the speed of the method. If bacterial isolates are present, it only takes a short time (hours) to identify many isolates. In the event that indicator bacteria, such as enterococci or coliform bacteria are detected, the rapid species identification can provide important information on the contamination source even on the day of the finding. With MALDI-TOF-MS, an innovative and rapid identification method is available at TZW especially for indicator bacteria relevant in drinking water supply. The identification can be very helpful for an evaluation of the findings and the investigation of causes. In this way, boil-water advisories can be prevented, provided that fecal contamination can be excluded on the basis of the examination results.
The quality of identification with the MALDI-TOF-MS - as with other identification methods - is highly dependent on the underlying database. Investigations at TZW have shown that enterococci can be identified reliably and quickly using MALDI-TOF-MS. For the group of coliform bacteria, comprehensive test results are also already available. By specifically supplementing the MALDI database with the spectra of various environmental coliform bacteria form, it was possible to improve identification in such a way that many isolates of coliform bacteria from drinking and surface water can also be correctly identified.
Current projects on MALDI-TOF-MS analysis at TZW
The MALDI-TOF-MS analysis is currently being used in various research projects to identify other hygienically relevant microorganisms such as Pseudomonas aeruginosa, Legionella, Campylobacter spp. or antibiotic-resistant bacteria from environmental samples.
MALDI-TOF MS for species identification in drinking water microbiology
Characterisation of the influence of groundwater reserves
Enterococci in drinking water systems
Development of valid methods for the detection of resistances (EVA)