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Type of publication: Master Thesis
Type of document:

Year: 2010

Authors: Abdel Fattah, Ahmed Abdel Moneim Mohamed

Title: Identification of some toxigenic aspergilli using matrix-assisted laser desorption / ionization coupled with time-of-flight mass spectrometry (MALDI-TOF-MS).

Source: Master Thesis, Vet. Med. Univ. Wien, pp. 66.


Advisor(s):

Razzazi-Fazeli Ebrahim

Reviewer(s):
Wagner Martin

Vetmed Research Units:
VetCore


Abstract:
Most identification tests used in the diagnosis of microorganisms are labour-intensive and time consuming. A new technology based on mass spectrometry named Matrix assisted laser desorption / ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) provides rapid identification of micro organisms from different origins. MALDI-TOF-MS is characterized by easy sample preparation, high sensitivity and high accuracy. Furthermore, small amount of sample are needed without time consuming. The microorganism e.g. fungi were cultivated on agar plates, then samples were collected directly from the agar plate to nourishing media, mixed with matrix, dried in air and introduced into the MALDI-TOF-MS for analysis. The spectra, which obtained were analysed, weather there are characteristic for every fungal species and strains respectively. In this work we studied the efficiency of MALDI-TOF-MS in the characterization and fingerprinting of thirty five isolates of Fungi on the basis of biomarker ions. We used α- cyano-4-hydroxycinnamic acid as matrix, which proof to give good mass spectra. Additionally, the effect of colony age on the mass spectra was investigated. We have found that the age of fungal colonies have no effect on mass spectral finger prints. Furthermore, the reproducibility and repeatability of spectra were investigated. It was found that the spectra were highly reproducible. According to the results of this study, MALDI-TOF-MS is only in some cases efficient for the characterization and fingerprinting of fungi. On the species level, biomarker ions, which obtained from this study made the differentiation between some aspergillus species possible (A. flavus, A. ochreseus, A. eucalypticola, A. carbonarius and A. awamori). However, in the case of A. niger, A. neoniger and A. tubingensi, A. brasiliensis, A. foetidus, A. piperis, A. vodensis, A. costariaeuis, A. bacticoflavus it was not possible to differentiate within and between the isolates of the species due to absence of appropriate biomarker ions.


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