The analysis software incorporates functionalities for the processing of mass spectra as well as for identification and classification. The processing parameters for smoothing, data reduction or baseline correction are user definable and the result is a dedicated peak list.

Pattern matching, for identification of unknown microorganisms, is accomplished through comparison of the generated peak lists with a library of stored spectra which contain the characteristic spectra information of species and subspecies. The software automatically generates the peak lists and extracts the typical peaks which are present in a certain number of spectra from one species.

Microorganism Identification

Identification of unknown microorganisms is performed by comparing their individual peak lists to the database. A matching score based on identified masses and their intensity correlation is generated and used for ranking of the results.

To increase the confidence of database searches MALDI Biotyper™ is able to correct peak mass deviations through a sophisticated recalibration algorithm. After peak picking it is possible to set an initially accepted error window and a desired adjustment result. The software can adapt the calibration from a new peak list to the known peak list in adjustable borders. Even spectra with mass deviation of 5000 ppm can be identified successfully. This functionality makes the MALDI Biotyper identification exceptionally robust and accurate. For dereplication, clustering and generation of family trees MALDI Biotyper offers a variety of functionalities:

• calculate the similarity of all main spectra in a library with each of the other spectra in this set by pattern matching. Based on the similarity scores dendrograms can be constructed.
• an unsupervised multivariate analysis based on principle component analysis is possible for a set of spectra. Based on the calculated principle components a variety of clustering algorithms and visualizations are available.

Applications

MALDI-TOF MS bacteria identification offers an excellent alternative to traditional laboratory methods in a variety of domains, e.g. environmental research, food and water control, quality control of microorganism collections, veterinary and medical diagnostics (for research use only).

The speed and minimal costs of sample preparation and measurement for this method makes it exceptionally well suited for routine and high-throughput use.

A further field of application is the analysis of taxonomic relationships. MALDI-TOF MS profile analysis results in similar family trees compared to classical methods.

Dereplication of complex microorganism communities based on their mass pattern offers new scientific capabilities, e.g. in environmental research and investigations of biodiversity. Thousands of microorganisms can easily be analyzed and serve as the basis for further analysis.