Affiliation:
1. Department of Life and Food Science, Suzhou University , Suzhou , 234000 , China
Abstract
Abstract
l-Cysteine is widely used in food, medicine, and cosmetics. In this study, a recombinant Escherichia coli whole-cell system with tryptophan synthase was used to complete the biological transformation of l-serine to l-cysteine, and bioconversion of l-cysteine was investigated by tryptophan synthase. The biotransformation of l-cysteine was optimized by response surface methodology. The optimal conditions obtained are 0.13 mol·L−1
l-serine, 75 min, 130 W ultrasound operation, where the V
max of tryptophan synthase is 25.27 ± 0.16 (mmol·h−1·(g-cells)−1). The V
max of tryptophan synthase for the biosynthesis without ultrasound is 12.91 ± 0.34 (mmol·h−1·(g-cells)−1). Kinetic analysis of the recombinant Escherichia coli whole-cell system with tryptophan synthase also showed that under the ultrasound treatment, the K
m values of l-cysteine biosynthesis increase from 1.342 ± 0.11 mM for the shaking biotransformation to 2.555 ± 0.13 mM for ultrasound operation. The yield of l-cysteine reached 91% after 75 min of treatment after 130 W ultrasound, which is 1.9-fold higher than no ultrasound.
Subject
Health, Toxicology and Mutagenesis,Industrial and Manufacturing Engineering,Fuel Technology,Renewable Energy, Sustainability and the Environment,General Chemical Engineering,Environmental Chemistry