Enzymatic synthesis of l-tryptophan from hair acid hydrolysis industries wastewater with tryptophan synthase

An effective method for production of l-tryptophan from hair acid hydrolysis wastewater (HHW) containing l-serine was developed by recombinant tryptophan synthase. This study provides us with an alternative HHW utilization strategy. Tryptophan synthase could efficiently convert l-serine contained in HHW to l-tryptophan at pH 8.0, 40 °C and Tween-80 of 0.04%. The enzyme also showed high tolerance to ammonium chloride, a component in HHW. In a scale up study, l-serine conversion rate reach 95.1% with a final l-tryptophan concentration of 33.2 g l−1.