MICROVIRGULA AERODENITRIFICANS GEN. NOV., SP. NOV., A NEW GRAM-NEGATIVE BACTERIUM EXHIBITING CO-RESPIRATION OF OXYGEN AND NITROGEN-OXIDES UP TO OXYGEN-SATURATED CONDITIONS

A denitrifier micro-organism was isolated from an upflow denitrifying filter inoculated with an activated sludge. The cells were Gram-negati ve, catalase- and oxidase-positive curved rods and very motile. They w ere aerobic as well as anoxic heterotrophs that had an atypical respir atory type of metabolism in which oxygen and nitrogen oxides were used simultaneously as terminal electron accepters. The G+C content was 65 mol%. Our isolate was phenotypically similar to Comamonas testosteron i, according to classical systematic classification systems. However, a phylogenetic analysis based on the 16S rRNA sequence showed that the aerobic denitrifier could not be assigned to any currently recognized genus. For these reasons a new genus and species, Microvirgula aerode nitrificans gen. nov., sp. nov., is proposed, for which SGLY2(T) is th e type strain.