A high-rate perfusion bioreactor for plant cells.
A perfusion bioreactor allowing continuous extraction of secondary metabolites was designed and challenged for Eschscholtzia californica plant cell suspensions. Four sedimentation columns mounted inside a 2.5-L bioreactor separated single cells and cell aggregates from the culture medium. Cells were elicited with chitin at day 4 and the liquid medium free of cells and debris was then continuously pumped to the extraction columns containing fluidized XAD-7 resins, and then recirculated back to the cell suspension. A medium upward velocity corresponding to cell sedimentation velocity maintained a stable cell/medium separation front in the columns for sedimented cell volume (SCV) of 90% (70% packed cell volume, PCV). Two perfusion bioreactor cultures of 10 and 14 days were performed. A maximum dilution rate of 20.4/day was reached from day 4 to day 6, and was then reduced to 5/day at day 9 for 55% SCV. Control cultures were performed without and with free extraction resins into the cell suspension. Perfusion cultures showed similar specific growth rates of 0.24 +/- 0.04/day before and after elicitation. However, production level in the perfusion cultures was similar to that from the culture without resins with a maximum of 2.06 micromole/gDW total alkaloids, with 1.54 micromole/gDW in the resins. Cultures with free resins resulted in 30.94 micromole/gDW with 28.4 +/- 8.8 micromole/gDW in the resins. Difference in the cells nutritional state from elicitation was identified as a major cause in the production reduction. However, pathway to chelilutine was favored in the continuous extraction culture.
De Dobbeleer
C
C
Canada Research Chair on the Development of Metabolic Engineering Tools, Bio-P2, Department of Chemical Engineering, Ecole Polytechnique de Montreal, Station Centre-Ville, Montreal, Quebec, Canada H3C3A7.
Cloutier
M
M
Fouilland
M
M
Legros
R
R
Jolicoeur
M
M
D000327:Adsorption; D000470:Alkaloids / Q000737:chemistry; D018533:Biomass; D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation* / Q000379:methods*; D018929:Cell Culture Techniques / Q000379:methods*; D004867:Equipment Design; D031675:Eschscholzia / Q000378:metabolism; D010477:Perfusion; D010944:Plants / Q000378:metabolism; D012116:Resins, Plant; D013997:Time Factors
D000470:Alkaloids; D012116:Resins, Plant