A. Negative-ion ESI-MS of [M-2H]2− ions of V. cholerae CL isolated from cultures grown in the presence and absence of bile. Selected peaks (*) found only in the presence of bile were subsequently analyzed by MS/MS.
B. Negative-ion MS/MS analysis of the [M-2H]2− ions at m/z 712.525 and 725.546 detected only in the presence of bile. The product-ion spectra show that these CL species contain longer, polyunsaturated fatty acyl chains (18:2, 20:4 and 22:5).