The aim and novelty of this paper are found in assessing the influence of inhibitors and antibiotics on intact cell MALDI-TOF mass spectra of the cyanobacterium Synechococcus sp. UPOC S4 and to check the impact on reliability of identification. Defining the limits of this method is important for its use in biology and applied science. The compounds included inhibitors of respiration, glycolysis, citrate cycle, and proteosynthesis. They were used at 1-10 μM concentrations and different periods of up to 3 weeks. Cells were also grown without inhibitors in a microgravity because of expected strong effects. Mass spectra were evaluated using controls and interpreted in terms of differential peaks and their assignment to protein sequences by mass. Antibiotics, azide, and bromopyruvate had the greatest impact. The spectral patterns were markedly altered after a prolonged incubation at higher concentrations, which precluded identification in the database of reference spectra. The incubation in microgravity showed a similar effect. These differences were evident in dendrograms constructed from the spectral data. Enzyme inhibitors affected the spectra to a smaller extent. This study shows that only a long-term presence of antibiotics and strong metabolic inhibitors in the medium at 10-5 M concentrations hinders the correct identification of cyanobacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF).

• Keywords
• MALDI, Synechococcus, antibiotic, cyanobacterium, inhibitor, metabolism,
• MeSH
• Anti-Bacterial Agents toxicity   MeSH
• Antimycin A analogs & derivatives   toxicity   MeSH
• Azides toxicity   MeSH
• Cell Respiration drug effects   MeSH
• Chloramphenicol toxicity   MeSH
• Citric Acid Cycle drug effects   MeSH
• Deoxyglucose toxicity   MeSH
• Fluoroacetates toxicity   MeSH
• Glycolysis drug effects   MeSH
• Malonates toxicity   MeSH
• Protein Biosynthesis drug effects   MeSH
• Pyruvates toxicity   MeSH
• Reproducibility of Results MeSH
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods   MeSH
• Weightlessness MeSH
• Streptomycin toxicity   MeSH
• Synechococcus chemistry   drug effects   isolation & purification   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Antimycin A MeSH
• antimycin MeSH Browser
• Azides MeSH
• bromopyruvate MeSH Browser
• Chloramphenicol MeSH
• Deoxyglucose MeSH
• Fluoroacetates MeSH
• fluoroacetic acid MeSH Browser
• Malonates MeSH
• malonic acid MeSH Browser
• Pyruvates MeSH
• Streptomycin MeSH