Destruction of Reducing Sugars by Resting Bacterium coli. ∗

The study of carbohydrates by the destructive action of yeast and bacteria has been carried out along different lines. 1 One of us 2 has caused differential sugar destruction by exposing test solutions to suspensions of resting yeast cells and then to bacterial growth. The present investigation was undertaken to study quantitatively the destruction of various sugars by resting bacteria grown upon sugar-free medium and medium enriched with various sugars.

A typical strain of B. coli (No. 4348 from the American Type Culture Collection) was grown upon a medium prepared as follows : Beef juice broth rendered sugar-free by the usual incubation with B. coli, filtered and adjusted to pH 7.6, 1.5% agar added. This mixture, alone or enriched with sugars, (0.5%) was slanted in culture tubes 1 inch in diameter. The slants were heavily seeded so that the entire surface was covered with organisms, and allowed to incubate at 37.5° C. for 18 hours. The growth was then removed with a small volume of physiological saline and the “resting” organisms washed at least twice with saline by centrifuging. About 0.45 to 0.55 cc. of packed organisms were suspended in 4 cc. of a solution containing 2.85% Na₂HPO₄ and 1.005% NaH₂PO₄. The suspension was brought to a temperature of 37.5° C. in a water bath, 2 cc. of an aqueous solution of carbohydrate† at the same temperature added, the contents of the tubes thoroughly mixed and incubation carried out for 10 minutes in the water bath.