2P-33 PDF
Cyanobacterial classification and toxin detection using MALDI Biotyper
MALDI-TOFMS has been used for bacterial profiling. A few reports have shown MALDI-MS profiling of isolated/cultured cyanobacteria; however, these applications have been limited. In this study, we have investigated whether rapid profiling and differentiation of cyanobacteria including harmful genera Microcystis and Anabaena (Dolichospermum) can be performed by MALDI Biotyper analysis of intact cells. Furthermore, we aimed to simultaneously detect small molecule toxins such as microcystins by extending the mass range. Intact cyanobacterial cells obtained from the NIES collection were deposited on a target plate, and analyzed using an Autoflex Speed MALDI-TOF mass spectrometer with Biotyper software (Bruker). Mass spectra obtained with the default mass range (m/z 2000-20000), or an extended mass range (m/z 400-20000), were used for clustering and spectral library searching of cyanobacterial strains. MALDI-MS analysis of cultured cyanobacterial cells showed clear ion signals under optimized conditions. Hierarchical clustering of mass spectra resulted in a tight cluster of Microcystis strains which was clearly differentiated from a cluster of Anabaena strains. Extending the mass range to low molecular weight enabled microcystin detection only from toxic Microcystis strains. In conclusion, we have demonstrated that MALDI-MS in combination with Biotyper analysis is applicable to profiling of toxic and non-toxic cyanobacterial strains.