A Specific Carbohydrate from Bacterium Enteritidis.

Abstract

During recent experiments with the soluble antigens of Bacterium enteritidis, large quantities of toxic Berkefeld filtrates of cultures grown in a simple salt medium were evaporated to dryness in vacuo, and this dry residue subsequently dialyzed. During the dialysis a grayish white precipitate settled out of the material in the dialyzing sac. This precipitate gave none of the usual protein tests; i. e., biuret, Millon, vanillin, diazo, or ninhydrin; but it gave a brilliant Molisch test, indicating that it contained carbohydrate. Saline extracts of this material gave precipitin reactions with B. enteritidis antiserum, and not with any other serum tested.

Sixty per cent, by weight, of the material in this precipitate proved to be inorganic, and was chiefly diatomaceous earth from the Berkfeld filters used; 40 per cent was organic matter.

The carbohydrate was separated from the diatomaceous earth with difficulty. Either it is very slightly soluble in ordinary solvents, or it is adsorbed by the diatomaceous earth. The most satisfactory method tried so far has been the following: The dry carbohydrate-containing material was heated for 1 1/2 hours at 150° C. A weighed amount was placed in a small flask, distilled water added, and the suspension autoclaved at 5 pounds pressure for 3 hours. The diatomaceous earth was then removed by centrifugalization, and the supernatant fluid evaporated to dryness on a water bath. The small white residue adheres to the dish and does not redissolve readily, but it is sufficiently soluble to give a vivid Molisch test and a specific precipitin reaction with Bacterium enteritidis antiserum. In this way 77 per cent, by weight, of the organic matter was extracted from the diatomaceous earth mixture.