Improvement of production yield of l-cysteine through in vitro metabolic pathway with thermophilic enzymes

The demand for the amino acid l-cysteine is increasing in food, cosmetic, and pharmaceutical industries. Conventionally, commercial production of achieved by its extraction from hydrolysate hair feathers. However, this method associated with release environmentally hazardous wastewater. Additionally, produced animal sources cannot be halal-certified, which limits market size. Although recent studies have developed an alternative based on microbial fermentation, yield was insufficient owing to cytotoxicity against host cells. In a previous study, we had vitro combination 11 thermophilic enzymes, yielded 10.5 mM 20 glucose. performed re-screening enzymes catalyzing rate-limiting steps pathway. Subsequently, genes encoding necessary synthesis were assembled expression vector co-expressed single strain. To prevent hydrogen peroxide (H2O2), byproduct inhibits enzyme activity, redox balance biosynthetic pathway maintained replacing H2O2-forming NADH oxidase another enzymatic reaction pyruvate used as sacrificial substrate. re-designed synthetic resulted 28.2 glucose molar 70.5%.