EFFICIENT L-DOPA PRODUCTION BY STIZOLOBIUM-HASSJOO CELL-CULTURE IN A 2-STAGE CONFIGURATION

A medium composition which favors the growth of plant cells may be sub -optimal for the production of secondary metabolites and vice versa. A two-stage culture system was examined in the present study to overcom e this problem. Efficient production of L-DOPA (3,4-dihydroxyphenylala nine) by Stizolobium hassjoo cell culture was attempted by reformulati ng the MS (Murashige-Skoog) medium to one more suitable for L-DOPA pro duction. The concentrations of the carbon and nitrogen sources, inorga nic nutrients, trace elements and organic supplements in the basal MS medium were optimized for L-DOPA production. Concentrations of phospha te, Ca++ and Zn++ corresponding to 20, 10 and 0% of the levels present in MS medium maximized L-DOPA content. Also, elimination of the organ ic supplements and some inorganic compounds enhanced L-DOPA production . Medium adjustment conducted in our previous work, particularly Cu++, Co++, IAA (indole-3-acetic acid), was also taken into consideration. A medium tailored to the efficient production of L-DOPA in the second stage of a two-stage culture system was elaborated. Validation of the medium in shake flasks resulted in 2.1-2.3 fold increases in L-DOPA co ntent compared to the control medium. Validity tests of the production medium in large laboratory-scale bioreactors were also conducted. By adequate control in aeration and agitation rates for each bioreactor, remarkable enhancement of L-DOPA production was obtained. The L-DOPA c ontent (% dry weight) in 1-1 round bottom spinner flask increased 4-fo ld of the initial content. Thus, the possibility of scaling-up two sta ge cultures was shown. (C) 1998 Elsevier Science B.V. All rights reser ved.