Brucella Ornithine Lipids Figure 1. Brucella abortus OLs are OM components synthesized in a two step pathway. (A). Thin layer chromatography analysis of total free- lipid extracts of: (1), BAB-parental cells grown in tryptic soy broth; (2), OM fragments of BAB-parental; (3), BAB-parental crude LPS; (4) BAB-parental grown in minimal medium; (5), BABDolsB cells; (6), BABDolsA cells; and (7), BABDolsB complemented with pLPI6. (B), proposed OL synthesis pathway [adapted from [87]]. The identities of Brucella OL acyl chains are from reference [88] and the genetic evidence. (C), proposed structures of OL of bacteria of various phylogenetic groups. doi:10.1371/journal.pone.0016030.g001 (Figure 3 A). Although small differences in antibody-independent complement activation were suggested when large amounts of bacteria were used (Figure 3 B), the differences were not statistically significant (p.0.05). Finally, we also tested the surface hydrophobicity of the mutants and the exposure of major OM proteins. The partition coefficient of the wild type BAB-parental Figure 2. B. abortus OL-deficient mutants are not sensitive to polymyxin B, lysozyme or EDTA. Late exponential phase bacterial suspensions in HEPES (pH 7.5) were exposed to combinations of polymyxin B (100 units/ml), lysozyme (50 mg/ml) and EDTA (5 mM) and bacterial lysis followed turbidimetrically. doi:10.1371/journal.pone.0016030.g002 PLoS ONE | www.plosone.org 3 January 2011 | Volume 6 | Issue 1 | e16030