Studies On The Bioconversion Of Cysteine Of Pseudomonas F-12and The Engineered Strain Construction

Cysteine is one of the basic units of proteins. Cysteine is widely used in medicines, cosmetics, and food additives. Traditionally, it is produced mainly from hair hydrolysis. However, this process has many disadvangtages such as low yield, unpleasant odors and serious environmental pollution. There have been some reports using microorganism to produce L-cysteine.The microbial conversion can achieve high yield and be friendlier to the environment. Pseudomonas sp. F-12has potential to produce L-cysteine through hydrolysis of D, L-2-amino-△2-thiazoline-4-carboxylic acid (DL-ATC). In this study, we used different fermentation strategies. The maximum enzymatic activity in batch fermentation reached to149.1U/mL The highest enzymatic activity in fed-batch fermentation reached to313.3U/mL. The effects of different conditions on the conversion of L-cysteine, such as pH, the concentration of tsubstrate, temperature, hydroxylamine, and metal ions were investigated and optimized. Determine the optimal conversion conditions of Pseudomonas sp. F-12. The optimum concentration of conversion solution was10g/L, pH8.0. Adding hydrochloride can significantly inhibit the cysteine sulfhydryl enzyme. Additionally, three enzymes being responsible for DL-ATC biotransformation were cloned and the recombinant strains were constructed.