Production of an Unsaturated Compound by B. coli in a Synthetic Medium

Abstract

Production of unsaturated acids by bacteria in synthetic media has apparently rarely been observed. When B. coli were grown in a media∗ of known composition, it was noted that acidity continued to increase even when tests showed the absence of lactic, acetic and aceto-acetic acids, and it was noted that the media readily absorbed bromine and iodine and decolorized potassium permanganate.

Cultures were made in large quantities of the media and allowed to grow for a period of 20 days. If tests for dextrin, reducing sugars, lactic acid ammonia, nitrites and nitrates were negative, the test for tartrate ion (alpha-beta-hydroxy-acid)† was less marked than in the control media and the pH was 5.0 or lower, the media was freed of the organisms by filtration through a Seitz filter. The filtrate was extracted 2 or 3 times with ether (free from peroxides). The ether was distilled from the extract. The residue, a water-clear liquid, was dissolved in a small quantity of water and reextracted with ether. The ether from the second extraction was removed by spontaneous evaporation in the dark, since light seemed to cause polymerization of the residue.

The residue, a water-like, colorless liquid, as stated above had the following qualities:

A strong acetic odor; readily soluble in water, ether, alcohol, and chloroform, a melting point of about 6°C. It was readily decomposed by sunlight but more slowly by diffuse light. Some of the extract was placed in a small vial, was kept in the icebox, but even under these conditions the material decomposed within 3 days.

It was found that 0.08 cc. of the liquid when dissolved in 3cc. of 10% sodium carbonate solution decolorized more than 8 cc. of a 1% solution of potassium permanganate leaving a brown precipitate of manganese oxides; 0.13 gm. of the liquid dissolved in 2 cc. of carbon tetrachloride to which was added 3 drops of brom-solution (2 cc. of bromine to 50 cc. carbon tetrachloride) caused the decomposition of the bromine solution instantaneously without the evolution of hydrobromic acid.