Rhodanobacter denitrificans

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IN PROGRESS

Classification

Taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae; Rhodanobacter; denitrificans [8].

Strains

2APBS1 and 116-2 [8].

Description

Rhodanobacter denitrificans is a yellow-pigmented, gram-negative, non-sporulating, motile,slow-growing, and facultatively anaerobic rod-shaped bacterium with the ability to perform complete denitrification [8]. For Rhodanobacter species, denitrification was not a characteristic until the discovery of R. denitrificans [6]. Denitrification is the conversion of nitrate to N2 through nitrite, nitric and nitrous oxide intermediates catalyzed by microbial enzymes [11]. Only two species of Rhodanobacter, one of them being Rhodanobacter denitrificans, is capable of this process [8]. In the absence of oxygen, growth is fueled by the use of nitrate, nitrite, and nitrous oxide as electron acceptors [8]. Rhodanobacter denitrificans has a salt tolerance up to 2% NaCl [8]. Growth was observed at pH 4-8 and 10-35ºC, optimally at pH 6.5 and 30ºC [8]. The two strains of R. denitrificans, 2APBS1 and 116-2, were found at Oak Ridge Integrated Field Research Challenge (ORIFRC) [8]. ORIFRC is a model nuclear legacy site with high levels of nitrate and acidity, with uranium and other heavy metal contaminants [8]. At ORIFRC, 2APBS1 was isolated from Area 2 (pH 6-7 and nitrate level <2 mM) and 116-2 was isolated from Area 3 (pH 3-4 and nitrate level 10s to 100s mM) [8]. The two strains are highly abundant and active in acidic, nitrate rich subsurface environments with high metal (e.g. uranium) concentrations [8]. The characteristic of survival in these harsh environments allow R. denitrificans to conduct bioremediation of the contamination sites by denitrification [8].