title: The influence of culture conditions on the identification of Mycobacterium species by MALDI-TOF MS profiling.
abstract: Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) represents a simple reliable approach for rapid bacterial identification based on specific peptide/protein fingerprints. However, cell-wall characteristics of mycobacterial species, and their well known stability, complicate MALDI-TOF MS profiling analysis. In this study, we tested two recently published protocols for inactivation and disruption of mycobacteria, and we also examined the influence of different culture conditions (four culture media and five cultivation times) on mass spectral quality and the discriminatory power of the method. We found a significant influence of sample pretreatment method and culture medium on species identification and differentiation for a total of 10 strains belonging to Mycobacterium phlei and Mycobacterium smegmatis. Optimum culture conditions yielding the highest identification success rate against the BioTyper database (Bruker Daltonics) and permitting the possibility of automatic acquisition of mass spectra were found to be distinct for the two mycobacterial species examined. Similarly, individual changes in growth conditions had diverse effects on the two species. For these reasons, thorough control over cultivation conditions should always be employed to maximize the performance and discriminatory power of MALDI-TOF MS profiling, and cultivation conditions must be optimized separately for individual groups of mycobacterial species/strains.
authors.affiliation: Research Group Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Microbiology, Faculty of Science, Masaryk University, Brno, Czech Republic.
authors.forename: Tereza
authors.initials: T
authors.lastname: Balážová
authors.forename: Jitka
authors.initials: J
authors.lastname: Makovcová
authors.forename: Ondrej
authors.initials: O
authors.lastname: Šedo
authors.forename: Michal
authors.initials: M
authors.lastname: Slaný
authors.forename: Martin
authors.initials: M
authors.lastname: Faldyna
authors.forename: Zbyněk
authors.initials: Z
authors.lastname: Zdráhal
mesh_terms: D015373:Bacterial Typing Techniques; D003470:Culture Media / Q000494:pharmacology*; D009161:Mycobacterium / Q000187:drug effects*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D003470:Culture Media
keywords: MALDI-TOF MS; Mycobacterium phlei; Mycobacterium smegmatis; mycobacteria profiling; strain differentiation