An extracellular glycolipid produced by Escherichia coli grown under lysine-limiting conditions.

1. Some of the products excreted by cultures of lysine-requiring Escherichia coli A.T.C.C. 12408 grown under lysine-limiting conditions have been studied. 2. A glycolipid designated ;extracellular lipoglycopeptide' was prepared from culture filtrates of such organisms. It contained 35% of lipid, 19% of carbohydrate, 3.4% of P and 3.7% of N. 3. Comparison of the lipids, fatty acids, carbohydrates and amino acids of this lipoglycopeptide with those of whole cells, cell walls and cellular lipopolysaccharides shows that it has few features (except its residual lipids) in common with any of these fractions. 4. The lipoglycopeptide was antigenically related to both walls and lipopolysaccharide.