(1) The role of fumarate metabolism in the microaerophily of the Campylobac
ter. genus and the effects of therapeutic agents against it were investigat
ed. (2) NMR spectroscopy was employed to determine the properties of Campyl
obacter fumarase (Fum) and fumarate reductase (Frd). Radiotracer analysis w
as used to determine the production of carbon dioxide by Campylobacter cell
s. Standard microbiological techniques were used to measure the effects of
environmental conditions and inhibitors on bacterial growth. (3) All Campyl
obacter species tested showed both Fum and Frd activities. Frd activity was
observed with or without the addition of an exogenous electron donor in th
e particulate fractions obtained from lysates. Fumarate was oxidized to car
bon dioxide via the acetyl-CoA cleavage pathway. The genes encoding protein
s involved in fumarate metabolism were identified in the Campylobacter jeju
ni genome. Cells grew better in atmospheres with 5 and 10% oxygen levels. F
um activity was the same in cultures grown under different oxygen tensions
and did not vary with the age of cultures. Frd activity was higher in cultu
res which grew at faster rates and decreased with the age of cultures. Four
Frd inhibitors showed bactericidal effects against Campylobacter spp. with
different potencies. The relative strengths of inhibition of the compounds
followed the same order as the bactericidal effects. (4) The results sugge
sted that Frd and Fum are constitutive and play a fundamental role in these
microaerophiles which show characteristics of anaerobic metabolism, and th
at the Frd inhibitors tested would not be of therapeutic use. (C) 1999 Else
vier Science Ltd. All rights reserved.