Extraction, distribution and biodegradation of bacterial lipopolysaccharides in estuarine sediments

Lipopolysaccharides (LPS), added as whole bacteria to estuarine sediments, were extracted efficiently by both trichloroacetic acid (TCA) and phenol--water (PW). Amounts of recovered LPS were measured indirectly by analyses for ketodeoxyoctonate (KDO), beta-hydroxymyristic acid, immunodominant sugars and anticomplementary (AC) activity towards human complement. TCA was judged to be better than PW for routine extraction of sediments because, although it yielded 10--20% less LPS, it avoided contamination with non-LPS, high-molecular weight material with high AC activity. In sediment samples taken as cores from estuarine beaches, the concentration of endogenous LPS diminished rapidly with depth below the topmost 1 cm. KDO disappeared more rapidly with depth than AC activity. When known LPS was incubated with estuarine beach mud at 20--22 degrees C for 3 weeks there was extensive biodegradation of both the lipid and polysaccharide components, the latter more rapidly. LPS-degrading bacteria were isolated.