Abstract:

Pseudomonas sp. TS1138 has potential to produce L-cysteine synthetase through asymmetrical hydrolysis of DL-2-amino-Δ2-thiazoline-4-carboxylic acid (DL-ATC). The effect of dissolved oxygen level on the production of L-cysteine synthetase was investigated in shake flasks or 7 L bioreactor. Results indicated that the cell growth and the production of L-cysteine synthetase were inhibited at low dissolved oxygen level. Although cell growth was improved at the high dissolved oxygen level, the inhibition against production of L-cysteine synthetase was still observed in shake flasks. In 7 L bioreactor, dissolved oxygen concentration controlled at more than 30% was helpful for improving the cell growth and the production of L-cysteine synthetase through regulating agitation rate and air flow rate during the middle and late stage.

Key words: L-cysteine, dissolved oxygen, Pseudomonas sp.