A PYROLYSIS MASS-SPECTROMETRY STUDY OF TEMPERATURE-DEPENDENT COMPOSITIONAL SHIFTS IN XANTHOMONAS (PSEUDOMONAS) MALTOPHILIA

Xanthomonas (Pseudomonas) maltophilia strains are frequently susceptib le to aminoglycoside antibiotics and polymixin B when incubated at 37 degrees C, but resistant at 30 degrees C. Five strains showing tempera ture dependent resistance, and five that did not were examined by pyro lysis-mass spectrometry, a characterisation method that gives fingerpr int data reflecting cell composition. Cultures grown at 30 degrees C a nd 37 degrees C in the absence of antibiotics were analysed. Strains s howing temperature-dependent resistance exhibited a characteristics co mpositional difference between cells grown at the two temperatures, wh ereas 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 constit uents.