A Study of D-arabinose Fermentation

Abstract

A study was made of the delayed fermentation of d-arabinose by certain members of the coli-aerogenes. paratyphoid and dysentery groups of bacteria. Increased concs. of d-arabinose in broth, 2% and 5%, did not accelerate fermentation, except in the case of Aerobacter aerogenes. Use of shallow layers of medium to afford greater aeration did not accelerate splitting of the sugar. Anaerobic or partial anaerobic conditions did not appreciably hasten the slow fermentation. In a synthetic medium with d-arabinose as the only source of energy most of the organisms were unable to initiate development. The late fermentation was accelerated by serial passages in d-arabinose broth and cultures which had been subjected to this procedure produced fermentation usually within 24 hrs. After acquiring ability to ferment rapidly the d-form of the sugar, no alteration in behavior toward the Worm or toward other common sugars could be detected. Also, this ability was retained by many cultures for periods up to 2 yrs. beyond which the tests were not carried. On d-arabinose agar plates daughter colonies or papillae containing rapidly-fermenting variants gradually appeared within the original non-fermenting colonies. When cells were removed from d-arabinose broth cultures just before fermentation became evident and were transferred to new tubes of the same medium, fermentation appeared promptly. When filtrates of d-arabinose broth cultures, from which the cells had been removed just prior to evident fermentation, were re-inoculated with new cells which had not previously been in contact with d-arabinose, the fermentation was delayed. During the period before evident fermentation the principal change appears to be an alteration in the cells and not a conversion of the d-form of the sugar to some more readily assimilable form before it is finally broken down.