Presence of Cu-Type (NirK) and <i>cd</i><sub>1</sub>-Type (NirS) Nitrite Reductase Genes in the Denitrifying Bacterium <i>Bradyrhizobium nitroreducens</i> sp. nov.

Abstract

Nitrite reductase is a key enzyme for denitrification. There are two types of nitrite reductases: copper-containing NirK and cytochrome cd 1 -containing NirS. Most denitrifiers possess either nirK or nirS, although a few strains been reported to possess both genes. We herein report the presence of nirK and nirS in the soil-denitrifying bacterium Bradyrhizobium sp. strain TSA1 T . Both nirK and nirS were identified and actively transcribed under denitrification conditions. Based on physiological, chemotaxonomic, and genomic properties, strain TSA1 T (=JCM 18858 T =KCTC 62391 T ) represents a novel species within the genus Bradyrhizobium, for which we propose the name Bradyrhizobium nitroreducens sp. nov.