Nitrate-dependent [Fe(II)EDTA]2- oxidation by Paracoccus ferrooxidans sp nov., isolated from a denitrifying bioreactor

Enrichments with [Fe(II)EDTA](2-) as electron donor and nitrate or nitrite as electron acceptor were established using an inoculum from a bioreactor performing denitrification. A nitrate-reducing, [Fe(II)EDTA](2-) oxidizing strain was isolated and named strain BDN-1. The G + C content of strain BDN-1 was 67%, and the organism was closely affiliated to Paracoccus denitrificans, P. pantotrophus and P. versutus by 16S rRNA sequence comparison. Results from DNA-DNA hybridization, rep-PCR., and whole cell protein analysis gave congruent results confirming the genotypic and phenotypic differences between strain BDN-1 and the other species of Paracoccus. From these results, we considered strain BDN-1 as a novel species for which we propose the name Paracoccus ferrooxidans. Apart from [Fe(II)EDTA]2-, BDN-1 could also use thiosulfate and thiocyanate as inorganic electron donors. Nitrate, nitrite, N2O, [Fe(II)EDTA(.)NO](2-) and oxygen could be used by strain BDN-1 as electron acceptors. Repeated transfer on a culture medium with bicarbonate as the sole carbon source confirmed that strain BDN-1 was a facultative autotroph. [Fe(II)EDTA]2- oxidation dependent, denitrification was also performed by other Paracoccus species, that were closely affiliated to P. ferrooxidans. (c) 2005 Elsevier GmbH. All rights reserved.