Campylobacter nitrofigilis sp. nov., a Nitrogen-Fixing Bacterium Associated with Roots of Spartina alterniflora Loisel

Abstract

Obligately microaerophilic, N2-fixing bacteria are associated with roots of S. alterniflora Loisel and in root-associated sediments from salt marshes in Nova Scotia, Canada and Georgia, USA. These bacteria differ from previously described species and thus represent a new species. The cells of all strains which were studied are small, rigid, curved, motile and rod shaped and have single polar flagella. Metabolism is respiratory and the strains utilize organic and amino acids, but not carbohydrates, as sole Ca sources. Poly-.beta.-hydroxybutrate is not produced. These traits and the guanine-plus-cytosine contents of the DNA of these strains (28.3 .+-. 0.1 mol%) indicate that they are members of the genus (Campylobacter Sebald and Veron 1963. These strains can be distinguished from the previously described Campylobacter spp. by the presence of nitrogenase, by their tolerance of and apparent requirement for NaCl, by the production of pigment from tryptophan, by a combination of other biochemical traits and by their association with plant roots. These strains represent a new species, C. nitrofigilis. Strain CI (= ATCC 33309) was designated as the type strain.