Frequency of occurrence of native hapten among enterobacterial species.

Anacker, R. L. (Rocky Mountain Laboratory, Hamilton, Mont.), W. D. Bickel, W. T. Haskins, K. C. Milner, E. Ribi, and J. A. Rudbach. Frequency of occurrence of native hapten among enterobacterial species. J. Bacteriol. 91:1427-1433. 1966.-Smooth cultures of representative Enterobacteriaceae were screened for the presence of native hapten, a substance previously extracted with trichloroacetic acid from the protoplasmic fraction of one strain each of Escherichia coli O111:B4 and O113. Trichloroacetic acid extracts of protoplasmic fractions of the cells were analyzed for chemical composition, for constituent sugars by paper chromatography, for immunochemical relationship to endotoxin purified by gel filtration, for sedimentation behavior, and for pyrogenicity in rabbits and lethal toxicity in chick embryos. Extracts from two of three additional strains of E. coli O113, all five additional strains of E. coli O111:B4, and one strain each of E. coli O26:B6 and O55:B5 were similar to previously described native hapten in chemical composition, sedimentation properties (S(20,w), 3.7 to 5.2), biological potency (usually less than 0.1% that of corresponding endotoxin), and immunochemical relationship to endotoxin. Extracts of one strain each of E. coli O127:B8, Serratia marcescens, Citrobacter freundii, Salmonella enteritidis, and of two lipopolysaccharide-deficient mutants of S. enteritidis differed from typical native hapten. The biosynthetic relationship of native hapten to endotoxin has not yet been revealed.