Characterization of N2O-producing Xanthomonas-like isolates from biofilters as Stenotrophomonas nitritireducens sp nov., Luteimonas mephitis gen. nov., sp nov and Pseudoxanthomonas broegbernensis gen. nov., sp nov.

A group of yellow-pigmented isolates from ammonia-supplied biofilters showe d an unusual denitrification reaction. All strains reduced nitrite but not nitrate without production of nitrogen (N-2). The only product found was ni trous oxide (N2O). The strains were divided into two clusters and one separ ate strain by their fatty acid profiles, which were similar to the fatty ac id profiles of the genera Xanthomonas and Stenotrophomonas. Analyses of the 16S rDNA sequences showed that these clusters and the separate strain form three independent lines within the Xanthomonas branch of the The evolution ary distances of the isolates to members of the related genera Xanthomonas, Stenotrophomonas and Xylella calculated by the 16S rDNA sequences led to t he proposal of two new genera and three new species, Stenotrophomonas nitri tireducens sp. nov., Luteimonas mephitis gen. nov., sp. nov. and Pseudoxant homonas broegbernensis gen. nov., sp. nov. The type strains are Stenotropho monas nitritireducens L2(T) (= DSM 125753(T)), Luteimonas mephitis B1953/27 .1(T) (= DSM 12574(T)) and Pseudoxanthomonas broegbernensis B1616/1(T) (= D SM 12573(T)).