Periplasmic location of dissimilatory nitrate and nitrite reductases in a denitrifying phototrophic bacterium, <italic>Rhodopseudomonas sphaeroides</italic> forma sp. <italic>denitrificans</italic>

Abstract

The localization of dissimilatory nitrate and nitrite reductases of a denitrifying phototrophic bacterium, Rhodopseudomonas sphaeroides forma sp. denitrificans, was investigated. Nitrate and nitrite reductases were located in the periplasmic space of the bacterium grown anaerobically in the presence of nitrate either in light or in darkness. Chromatophores showed nitrate and nitrite reductase activities when dithionite-reduced benzyl viologen was an electron donor; this suggests that the enzymes were trapped inside the vesicles.