A pyrolysis mass spectrometry study of temperature-dependent compositional shifts in Xanthomonas (Pseudomonas) maltophilia.

Xanthomonas (Pseudomonas) maltophilia strains are frequently susceptible to aminoglycoside antibiotic and polymixin B when incubated at 37 degrees C, but resistant at 30 degrees C. Five strains showing temperature dependent resistance, and five that did not were examined by pyrolysis-mass spectrometry, a characterisation method that gives fingerprint data reflecting cell composition. Cultures grown at 30 degrees C and 37 degrees C in the absence of antibiotic were analysed. Strains showing temperature-dependent resistance exhibited a characteristic compositional difference between cells grown at the two temperatures, whereas strains not showing this type of resistance varied widely in the extent and nature of temperature-dependent differences in composition. The precise nature of the chemical differences cannot be elucidated at present, but could be determined by examining purified cell constituents.