Ascertainment of D-amino acids in germ-free, gnotobiotic and normal laboratory rats

Free D-amino acids were ascertained in the blood serum, urine and aqueous e thanolic extracts of feces of germ-free laboratory rats and a rat made gnot obiotic (tetra-associated) with species of Streptococcus, Lactobacillus and Clostridium. D-Amino acids were also determined in the brains of two germ- free rats. For comparison, D-amino acids were also measured in the blood se rum of normal rats and the blood plasma, urine and feces of normal white mi ce. D-Enantiomers of most protein L-amino acids were detected in all physio logical samples of animals. Quantities of free D-amino acids were determine d as N(O)-pentafluoropropionyl-(2)-propyl esters by enantioselective gas ch romatography and mass spectrometry. Stereoisomers of the bacterial marker 2 ,6-diaminopimelic acid, analyzed as N-trifluoroacetyl-(2)-propyl esters, we re detected in feces of the gnotobiotic but not of the germ-free rat. Copyr ight (C) 2001 John Wiley & Sons, Ltd.