Fermentation of the d- and 1- Forms of Arabinose by Bacteria

Abstract

Although the commoner sugars have found an every day use in bacteriological technic for the separation and characterization of different types of bacteria, it is only rarely that optical antipodes have been subjected to comparative fermentation tests for the purpose of correlating sugar structure with utilization. 1 In most cases it is difficult or impossible to prepare both the d- and l- forms of a given sugar. Arabinose is one of the few exceptions to this rule.

The common form of arabinose is l-arabinose 2 ([α]_D = +105°), which occurs naturally in a combined form in many gums such as arabic and mesquite. It has been used in bacteriological work for a number of years. d-arabinose seldom occurs naturally and must be prepared from d-glucose by degradation. Recently we obtained 20 a supply of d-arabinose which had teen prepared by the oxidation of calcium gluconate with hydrogen peroxide in the presence of ferric acetate. This afforded us an opportunity to study the fermentation of both d-arabinose and l-arabinose, which are exact opposites in configuration and rotation.

The sugar solutions were sterilized by filtration through Seitz filters and added to nutrient broth to give a 1% solution of sugar in the culture medium. After inoculation the various cultures were held at 37° and observed at frequent intervals for 3 weeks. The results are shown in the accompanying table.

The common l-arabinose was fermented rapidly by many bacteria. It is quite striking that the synthetic d-arabinose was fermented with difficulty by all of the types which utilized l-arabinose readily. An interval of 4 to 7 days, or occasionally longer, was required for the break down of the d-arabinose to acid end products. Since all cultures developed readily in the d-arabinose broth it seems certain that the slow fermentation was not due to any restraining effect upon growth of the culture.