The fixation of CO2 by cell suspensions of Propionibacterium pentosaceum

Abstract

THE fixation of C02 by heterotrophic non-photosynthetic bacteria was first reported by Wood & Werkman [1936; 1938] in the case of the fermentation of glycerol by the propionic acid bacteria. It was established that the C02 utilized and the succinic acid formed are approximately equiimolar. These results have been confirmed by Phelps et al. [1939]. Wood & Werkman [1938] have sug-gested that succinic acid is formed in this fermentation by synthesis from a 3-carbon compound and C02. The present investigation is a continuation of these studies to deternmine whether similar considerations apply to the fermenta-tion of other substrates. It is inot improbable that the formation of succinic acid by synthesis from C02 and a 3,carbon compound may occur more generally than has been suggested. METHODS Barcroft-Warburg manometric technique was used according to Dixon [1934]. 2 ml. of mixture were used in each cup unless otherwise stated. The temperature of the bath was 300. The flasks were oscillated continuously 100 times per min. through an amplitude of 5 cm, Propionibacterium pentosaceum (49 W) was grown at 300 for 5 days in a medium of yeast extract (Difco) 0-4 %, glycerol 0-5 %, and