Intra-injector methylation of free fatty acids from aerobically and anaerobically cultured Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus.

Free fatty acids from the type strains of anaerobically and aerobically broth-cultured Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus cells were Soxhlet-extracted with hexane. The fatty acids were identified and quantified by gas chromatography and gas chromatography-mass spectrometry after intra-injector derivation with trimethylanilinium hydroxide. This derivatization method, which we propose as suitable for routine use in clinical microbiology, is fast, accurate and sensitive, with low toxicity. Whereas the fatty acid content of A. actinomycetemcomitans was affected by the cultivation atmosphere, i.e. C16:1, decreased under aerobic growth and C16:0 increased, that of the closely related H. aphrophilus was more stable.