A cytochrome P450 monooxygenase that catalyzes the biosynthesis of adrenal mineralocorticoid aldosterone. Catalyzes three sequential oxidative reactions of 11-deoxycorticosterone/21-hydroxyprogesterone, namely 11-beta hydroxylation followed with two successive oxidations at C18 to yield 18-hydroxy and then 18-aldehyde derivatives, resulting in the formation of aldosterone. Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate and reducing the second into a water molecule. Two electrons are provided by NADPH via a two-protein mitochondrial transfer system comprising flavoprotein FDXR (adrenodoxin/ferredoxin reductase) and nonheme iron-sulfur protein FDX1 or FDX2 (adrenodoxin/ferredoxin). a steroid + 2 H(+) + O2 + 2 reduced [adrenodoxin] = an 11beta-hydroxysteroid + H2O + 2 oxidized [adrenodoxin] 21-hydroxyprogesterone + 2 H(+) + O2 + 2 reduced [adrenodoxin] = corticosterone + H2O + 2 oxidized [adrenodoxin] corticosterone + 2 H(+) + O2 + 2 reduced [adrenodoxin] = 18-hydroxycorticosterone + H2O + 2 oxidized [adrenodoxin] 18-hydroxycorticosterone + 2 H(+) + O2 + 2 reduced [adrenodoxin] = aldosterone + 2 H2O + 2 oxidized [adrenodoxin] 11-deoxycortisol + 2 H(+) + O2 + 2 reduced [adrenodoxin] = cortisol + H2O + 2 oxidized [adrenodoxin] Steroid biosynthesis. Adrenal cortex. A 12-fold increase was seen in the presence of a low sodium-high potassium diet. Belongs to the cytochrome P450 family.