Involved in the biosynthesis of 4-methoxy-2,2'-bipyrrole-5-carbaldehyde (MBC), one of the terminal products involved in the biosynthesis of the red antibiotic prodigiosin (Pig). Catalyzes the oxidation of the hydroxy group of 4-hydroxy-2,2'-bipyrrole-5-methanol (HBM) to yield 4-methoxy-2,2'-bipyrrole-5-carbaldehyde (MBC). Antibiotic biosynthesis; prodigiosin biosynthesis. Cells lacking this gene show a white phenotype, and produce 2-methyl-3-n-amyl-pyrrole (MAP) and 4-hydroxy-2,2'-bipyrrole-5-methanol (HBM). Belongs to the nitroreductase family.