CHROMOGENIC ASSAY-METHOD OF LIPOPOLYSACCHARIDE (LPS) FOR EVALUATING BACTERIAL STANDING CROP IN SEAWATER

A chromogenic method, based on amoebocyte lysate of horseshoe crab and amino acids‐para‐nitroanilide substrate was employed to quantify lipopolysaccharide (LPS) as a measure of the bacterial standing crop in seawater. The range over which LPS could be reliably determined by this method was from 0.2 to 10 ng/ml of sample, and the method reported here could have several advantages compared with the turbidity determination method. Vertical distributions of total and particulate LPS were parallel in seawater column. Particulate LPS was not shown to be related to the biomass of total bacteria in some cases, but correlated with the numbers of large bacterial cells whose size was greater than 1 fan in length. In most of the profiles investigated in the shallow sea there was no parallel relationship between LPS and chlorophyll‐a whereas in some cases the profiles were similar. In growing cultures of Vibrio anguillarum the content of cellular LPS as a percentage of the total cellular carbon during the 3 d growth ranged from 6–15% (w/w). Copyright © 1979, Wiley Blackwell. All rights reserved