OXIDOREDUCTASE, NITRITE REDUCTASE, HIGH-THROUHPUT SCREENING, OXIDASE, COPPER, FAD, FLAVOPROTEIN, METAL-BINDING, NITRATE ASSIMILATION, PERIPLASM, PYRROLIDONE CARBOXYLIC ACID 3H4H MET94THR/PHE312CYS VARIANT OF NITRITE REDUCTASE FROM ALCALIGENES FAECALIS