Identification of microorganisms by gas chromatographic-mass spectrometric analysis of cellular fatty acids.

The cellular fatty acid compositions of strains of Pseudomonas aeruginosa, P. cepacia, and P. maltophilia were determined by gas-liquid chromatography. A variety of acids was detected in these organisms, including branched and straight-chain acids, cyclopropane, and hydroxy acids. Comparison of the presence and relative amounts of these acids was useful in distinguishing the three species. Three branched-chain hydroxy acids not found in other bacteria were present in P. maltophilia and were identified by gas chromatography, mass spectrometry, and infrared spectroscopy.