Characterization of alcohol dehydrogenase from Kangiella koreensis and its application to production of all-trans-retinol

A recombinant alcohol dehydrogenase (ADH) from Kangiella koreensis was purified as a 40 kDa dimer with a specific activity of 21.3 nmol min⁻¹ mg⁻¹, a Kₘof 1.8 μM, and a kcₐₜof 1.7 min⁻¹for all-trans-retinal using NADH as cofactor. The enzyme showed activity for all-trans-retinol using NAD ⁺ as a cofactor. The reaction conditions for all-trans-retinol production were optimal at pH 6.5 and 60 °C, 2 g enzyme l⁻¹, and 2,200 mg all-trans-retinal l⁻¹in the presence of 5 % (v/v) methanol, 1 % (w/v) hydroquinone, and 10 mM NADH. Under optimized conditions, the ADH produced 600 mg all-trans-retinol l⁻¹after 3 h, with a conversion yield of 27.3 % (w/w) and a productivity of 200 mg l⁻¹ h⁻¹. This is the first report of the characterization of a bacterial ADH for all-trans-retinal and the biotechnological production of all-trans-retinol using ADH.