Involved in the biosynthesis of the yellow-orange carotenoid staphyloxanthin, which plays a role in the virulence via its protective function against oxidative stress. Catalyzes the oxidation of 4,4'-diaponeurosporen-4-al to yield 4,4'-diaponeurosporenoic acid. 4,4'-diaponeurosporenal + H2O + NAD(+) = 4,4'-diaponeurosporenoate + 2 H(+) + NADH Carotenoid biosynthesis; staphyloxanthin biosynthesis; staphyloxanthin from farnesyl diphosphate. Cells lacking this gene are unable to produce staphyloxanthin and cause accumulation of 4,4'- diaponeurosporen-4-al. Belongs to the aldehyde dehydrogenase family.