What is it about?
Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), a powerful biotyping tool for the identification of bacteria and clinical yeast isolates, was investigated as a method to rapidly identify industrial S. cerevisiae strains. In this study, an optimized sample preparation protocol was devised for the biotyping of S. cerevisiae strains. The results demonstrate that ethanol/formic acid protein extraction, of a cell density of 1 × 108 cells co-crystallized with α-cyano-4-hydroxycinnmaic acid, is required to yield mass spectral profiles that are diagnostic of each strain type. Forty-four S. cerevisiae strains commonly employed in South African fermentation-based industries were biotyped in an attempt to create a yeast reference database within a local context. The data revealed that MALDI-TOF MS can be used for the rapid and accurate identification of laboratory and industrial S. cerevisiae strains.
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Why is it important?
In the present study, several parameters of an ethanol/formic acid extraction procedure were optimized to devise a sample preparation protocol for obtaining unique and highly reproducible MALDI-TOF MS spectra from S. cerevisiae strains. A yeast database within a local context was created, and its’ accuracy was tested using ‘unknown’ industrial samples. MALDI-TOF MS has the ability to differentiate closely related S. cerevisiae strains compared with the two molecular-based approaches/methods such as polymerase chain reaction (PCR) and contour-clamped homogenous electric field gel electrophoresis (CHEF).
Perspectives
MALDI-TOF MS does have certain limitations that are common to all MS-based approaches. This includes the differing abilities of proteins to form ions and hence varying signal intensities as well as ion-quenching phenomena, in which the signal from poor ionizing proteins is quenched by more easily ionized species, thereby suppressing the former signal [25]. These factors can result in a loss of sensitivity in discriminating closely related S. cerevisiae strains. Another limiting aspect of MALDI-TOF MS for S. cerevisiae identification is its reliance on a comprehensive database. In this study, it was demonstrated that MALDI-TOF MS has enormous potential to be used as a biotyping tool for the discrimination of S. cerevisiae strains. Future inter laboratory studies may lead to the development of a comprehensive strain-specific MALDI yeast database providing a powerful biotyping tool for the rapid, accurate and cost-effective identification of industrially important S. cerevisiae strains
Dr Suresh Babu Naidu Krishna
Durban University of Technology
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This page is a summary of: Biotyping Saccharomyces cerevisiae strains using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), European Food Research and Technology, January 2013, Springer Science + Business Media,
DOI: 10.1007/s00217-012-1898-1.
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