Ornithine‐containing lipids in Thiobacillus A2 and Achromobacter sp

20 bacterial strains (corresponding to 16 species) were screened for ornithine lipids. Only two species (Thiobacillus A2 and Achromobacter sp.) turned out to contain ornithine lipids (2.71 mmol/100 g and 0.38 mmol/100 g bacterial dry weight, respectively). In both ornithine lipids, a 3‐hydroxy fatty acid was amide‐linked to the α‐amino group of ornithine, a normal fatty acid was ester‐linked to the 3‐hydroxy group of the former. The predominant fatty acids were 18:1(11) and 3‐hydroxy‐20:1(13) in Thiobacillus A2, 16:0 and 3‐hydroxy‐18:1(11) in Achromobacter sp. All monounsaturated fatty acids (with one exception) belonged to the (n‐7) family. 11, 12‐Epoxy octadecanoic acid was identified among the ester‐linked fatty acids of Thiobacillus A2. Phosphatidyl‐choline was the principal phospholipid in both bacterial species.