Toxic and immunological differences among lipopolysaccharides from Thiobacillus ferrooxidans grown autotrophically and heterotrophically.

Lipopolysaccharides (LPS) extracted from Thiobacillus ferrooxidans grown on ferrous iron, elemental sulfur, or glucose as energy source were studied for general chemical composition, toxicity, and antigenic or immunogenic properties. LPS from iron-grown cells (Fe-LPS) and from glucose-grown cells (Glu-LPS) had similar chemical composition, but that from sulfur-grown cells (S-LPS) differed significantly, especially in content of hexosamine, 2-keto-3-deoxyoctonate, and heptose. All had weak to moderate endotoxic properties, but Fe-LPS was considerably more active than the others in the several assays performed. S-LPS was very weakly immunogenic; the other two stimulated strong antibody responses in rabbits. Immunodiffusion tests in agar gel revealed marked differences among the LPS antigens of cells grown with different energy sources.