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

Abstract

Obligately microaerophilic, nitrogen-fixing bacteria were found associated with roots of Spartina afternflora Loisel and in root-associated sediments from salt marshes in Nova Scotia, Canada, and Georgia. These bacteria differ from previously described species and thus represent a new species. The cells of all strains which we 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 carbon sources. Poly-p-hydroxybutyrate is not produced. These traits and the guanine-plus-cytosine contents of the deoxyribonucleic acids of these strains (28.3 ? 0.1 mol%) indicate that they are members of the genus Campyfobacter Sebald and Veron 1963. However, these strains can be distinguished from the previously described species of Campylobacter by the presence of nitrogenase, by their tolerance of and apparent requirement for NaC1, by the production of pigment from tryptophan, by a combination of other biochemical traits, and by their association with plant roots. Therefore, we propose that these strains represent a new species, Campylobacter nitrojigifis, and we designate strain CI (= ATCC 33309) as the type strain.Campyfobacter species are commonly occurring pathogens and commensal organisms that are associated with a diverse range of animal hosts (23, 24,31). Of particular interest in this genus is the Campyfobacter jejuni-Campylobacter cofi group (Campyfobacter fetus subsp. jejuni), which increasingly is being recognized as a cause of enteritis in humans (3, 10). In addition to the human-and animal-associated campylobacters, free-living strains of Campyfobacter have been isolated in culture (11, 15), but the taxonomic status of these organisms has not been established yet. One of the free-living strains, strain CIT (type strain), was found associated with the roots of Spartina afternflora Loisel growing in a salt marsh near Halifax, Nova Scotia, Canada; this strain was found to be capable of fixing nitrogen (15). In this paper we describe the isolation in culture of several additional nitrogen-fixing Campyfobacter strains from S. afternflora roots and root-associated sediments from a salt marsh on Sapelo Island, Georgia. We propose that these nitrogen-fixing, Spartina-associated strains represent a new species, Campyfobacter nitrojigifis. MATERIALS AND METHODSIsolation. Roots of S. altevnifora Loisel were taken from a salt marsh on Sapelo Island, Georgia, and were washed free of sediment in adjacent creek water. Root pieces (length, 2 cm) were placed in tubes of semisolid diazotroph medium (15). Other tubes were seeded with root-associated sediment samples. After 72 h at room temperature, the cultures were transferred to fresh tubes of semisolid malate-salts (MS) medium (15), and nitrogenase activity was determined by acetylene reduction assays (4). After 24 h, tubes of MS medium were capped with serum stoppers, and acetylene was injected to give a final partial pressure of C2Hz of 2 kPa...

Crenarchaeal heterotrophy in salt marsh sediments

“…Likewise, it was surprising that bacteria did not take up any carbon from urea at low concentrations, whereas the crenarchaea did. There is ample evidence of bacteria possessing urease genes (Collier et al, 2009;Solomon et al, 2010) and reports of Campylobacter nitrofigilis isolated from Spartina with urease activity along the United States eastern seaboard (McClung et al, 1983). While no bacterial activity was detected at 30 mM on urea, there was bacterial activity at 150 mM urea.…”

Arcobacter marinus sp. nov.

“…A. nitrofigilis was isolated from Spartina alterniflora roots in a salt marsh (McClung et al, 1983). A. halophilus and A. cibarius were isolated from a hypersaline lagoon (Donachie et al, 2005) and the skin of a broiler carcass (Houf et al, 2005), respectively.…”

Arcobacter mytili sp. nov., an indoxyl acetate-hydrolysis-negative bacterium isolated from mussels

“…The type species of the genus, A. nitrofigilis, was first recovered from the roots of Spartina alterniflora, a salt marsh plant (McClung et al, 1983), and since then there have been few reports on this species . A. butzleri is the most common species in environmental water, food and clinical samples (Ho et al, 2006).…”