Production of L-Dopa by immobilized Pseudomonas sp

PVA (polyvinyl alcohol) and Ca-alginate gel were selected as the immobilization carrier to stabilize the tyrosinase in Pseudomonas sp. for repeat production of L-Dopa from L-tyrosine. Comparing with the free cells, the Ca-alginate and PVA immobilized cells shortened the fermentation cycle by 8 hours and 14 hours respectively. In semi-continuous fermentation, the two kinds of immobilized cells were able to use 5 and 14 times repeatedly, and the fermentation efficiency were 16% and 160% higher than that of free cells. It was found that the productivity of L-Dopa was apparently increased when the PVA immobilized cells were treated with heat or shaken in the physiological saline solution. Excessive amount of substrate was unfavorable for the repeat use of immobilized cells.