Author idex volume 36 (1986)

Abstract Nitrate reduction to ammonia by marine Vibrio species was studied in batch and continuous culture. In pH-controlled batch cultures (pH 7.4; 50 mM glucose, 20 mM KNO₃), the nitrate consumed accumulated to more than 90% as nitrite. Under these conditions, the nitrite reductase (NO^?₂→ NH₃) was severely repressed. In pH-controlled continuous cultures of V. alginolyticus with glucose or glycerol as substrates ( D = 0.045 h^?1) and limiting N-source (nitrate or nitrite), nitrite reductase was significantly derepressed with cellular activities in the range of 0.7–1.2 μmol min^?1 (mg protein)^?1. The enzyme was purified close to electrophoretic homogeneity with catalytic activity concentrations of about 1800 nkat/mg protein. It catalyzed the reduction of nitrite to ammonia with dithionite-reduced viologen dyes or flavins as electron donors, had an M _r of about 50 000 (determined by gel filtration) and contained c-type heme groups (probably 4–6 per molecule).