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 desaturation of the L-prolyl-[PigG] to yield 1H-pyrrole-2-carbonyl-[PigG]. H(+) + L-prolyl-[peptidyl-carrier protein] + 2 oxidized [electron-transfer flavoprotein] = (1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + 2 reduced [electron-transfer flavoprotein] Antibiotic biosynthesis; prodigiosin biosynthesis. Cells lacking this gene show a white phenotype. Belongs to the acyl-CoA dehydrogenase family.