The Limulus assay was used to measure activities of naturally occurring and chemically extracted endotoxins and endotoxin fractions. Large amounts of both bound and free endotoxin were detected from gram-negative bacterial cells grown in either enriched or minimal media, and from resting cells. Following purification by phenol extraction, free endotoxin evidenced a similar level of activity to that of bound endotoxin. Lipid A and polysaccharide prepared by hydrolysis of endotoxin demonstrated reduced Limulus activity. However, R-strains from three species of gram-negative bacilli produced large amounts of free endotoxin. These results indicate that free endotoxin is part of the LPS that is readily released in a liquid environment, and probably is composed of lipid A and core material. In addition, a relatively constant amount of endotoxin remains bound on the cell surface, allowing an approximate quantitation of viable bacilli in fluids using the Limulus assay.
|Original language||English (US)|
|Number of pages||8|
|Journal||Proceedings of the Society for Experimental Biology and Medicine|
|State||Published - Sep 1974|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)