Microbiological Studies of Coli-aerogenes Bacteria

Part VII. Degradation of Citrate

Abstract

1) Glyoxylate and succinate were formed in addition to pyruvate and a-ketoglutarate, when the cell free extracts of coli-aerogenes grown on either glucose or citrate were incubated in the presence of citrate.
2) The fresh cell extracts of coli-aerogenes revealed a very poor potency of producing α-ketoglutarate with citrate, whereas, the addition of coenzyme II (TPN) to the reaction mixtures resulted in an increase in formation of α-ketoglutarate from citrate.
3) It was found with coli-aerogenes that iso-citritase existed in the various cells obtained from the following growth- media: bouillon-, peptone-, glucose-, acetate plus bouillon- suc-cinate plus bouillon- and citrate plus bouillon (Peptone)- media.
4) Isocitritase was demonstrable, even when coli-aerogenes was anaerobieally grown on a citrate-bouillon medium.
5) A large amount of glyoxylate was excreted in the external media, when not only the dried and ground cells of coli-aerogenes, but the intact (washed) cells of A. aerogenes were also incubated in the presence of citrate and a trapping agent such as semicarbazide.
6) Isocitric dehydrogenase existed in the cells of coli-aerogenes.
7) From the results obtained in the previous and present papers, it was strongly suggested that the intracellular concentration of coenzyme II of coli-aerogenes might be relatively low, so that coenzyme II-dependent isocitric dehydro-genase could not be operative at such a high rate sufficient to effect the complete removal of citrate.
8) It was indicated that the major degrada-tion of C₆-triearboxylie acids by coli-aerogenes took place by way of splitting reactions rather than depending on the isocitric-a-ketoglutaric dehydrogenase system.
9) With both C₃- and C₄-acids, α-ketoglutaratc was again ascertained to be obtainable in a high yield.