Role of Campylobacter jejuni Respiratory Oxidases and Reductases in Host Colonization

Abstract

ABSTRACT Campylobacter jejuni is the leading cause of human food-borne bacterial gastroenteritis. The C. jejuni genome sequence predicts a branched electron transport chain capable of utilizing multiple electron acceptors. Mutants were constructed by disrupting the coding regions of the respiratory enzymes nitrate reductase ( napA ::Cm), nitrite reductase ( nrfA ::Cm), dimethyl sulfoxide, and trimethylamine N -oxide reductase (termed Cj0264::Cm) and the two terminal oxidases, a cyanide-insensitive oxidase ( cydA ::Cm) and cbb3 -type oxidase ( ccoN ::Cm). Each strain was characterized for the loss of the associated enzymatic function in vitro. The strains were then inoculated into 1-week-old chicks, and the cecal contents were assayed for the presence of C. jejuni 2 weeks postinoculation. cydA ::Cm and Cj0264c::Cm strains colonized as well as the wild type; napA ::Cm and nrfA ::Cm strains colonized at levels significantly lower than the wild type. The ccoN ::Cm strain was unable to colonize the chicken; no colonies were recovered at the end of the experiment. While there appears to be a role for anaerobic respiration in host colonization, oxygen is the most important respiratory acceptor for C. jejuni in the chicken cecum.