Fumarate metabolism and the microaerophily Campylobacter species

(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.