Occurrence, identification and possible significance of ornithine lipid in Thiobacillus ferrooxidans

An ornithine containing aminolipid has been found in Thiobacillus ferrooxidans grown in ferrous sulfate medium, which was purified and estimated at four main phases of growth. GLC analysis of ornithine lipid has revealed the existence of mainly C18:1 and C22:1 fatty acids. The infrared spectra showed the existence of both amide and ester linkages in the aminolipid. The major ester linked fatty acid was C22:1. The interaction of ornithine lipid with membrane was investigated by delipidation of the membrane particles, which resulted in the perturbation of the activities of the three enzymes of iron oxidation system. The activities could be restored to the lipid depleted particles by preincubation with a dispersion of purified ornithine lipid together with coenzyme Q8. The kinetic parameters of the enzyme activities were also affected by delipidation which was significantly altered in the reconstituted particles by this lipid, thus indicating a possible role of ornithine lipid in iron oxidation system.