Na. Cornick et Mj. Allison, ASSIMILATION OF OXALATE, ACETATE, AND CO2 BY OXALOBACTER-FORMIGENES, Canadian journal of microbiology, 42(11), 1996, pp. 1081-1086
Oxalobacter-formigenes is the only well-documented oxalate-degrading b
acterium isolated from the gastrointestinal tract of animals. The prod
uction of ATP by Oxalobacter formigenes is centered around oxalate met
abolism and oxalate is required for growth. A small amount of acetate
(0.5 mM) is also required. Oxalate is decarboxylated to formate plus C
O2 in nearly equimolar amounts. Experiments were conducted to determin
e which potential carbon sources (oxalate, acetate, formate, CO2) were
assimilated by Oxalobacter formigenes and which metabolic pathways we
re operative in carbon assimilation. Measurements of the specific acti
vities of total cell carbon after growth with different C-14-labeled p
recursors indicated that at least 54% of the total cell carbon was der
ived from oxalate and at least 7% was derived from acetate. Carbonate
was also assimilated, but formate was not a significant source of cell
carbon. Labeling patterns in amino acids from cells grown in [C-14]ox
alate or (CO3)-C-14 were different; however, in both cases C-14 was wi
dely distributed into most cellular amino acids. Carbon from [C-14]ace
tate was less widely distributed and detected mainly in those amino ac
ids known to be derived from alpha-ketoglutarate, oxaloacetate, and py
ruvate. Cell-free extracts contained citrate synthase, isocitrate dehy
drogenase, and malate dehydrogenase activities. The labeling observed
in amino acids derived from acetate is in agreement with the function
of these enzymes in biosynthesis and indicates that the majority of ac
etate carbon entered into amino acid biosynthesis via well-known pathw
ays.