Kinetic analysis of continuous gossypol production from Gossypium arboreum using permeabilization, elicitation, and immobilization
Abstract
The purpose of this study was to develop a continuous process of secondary metabolite production from plant cells. A novel reactor with simultaneous use of plant cell immobilization, permeabilization, and elicitation was designed to enhance the productivity of secondary metabolites and to overcome limitations of plant cell culture such as slow metabolic rate, low product yield, and sensitivity to shear stresses. Production of gossypol, an anti-fungal agent, from Gossypium arboreum was selected as a model system. The effects of permeabilization, elicitation, and immobilization on gossypol production were investigated in free suspension culture, an immobilized plant cell reactor with recycled batch operation, and a bioreactor with continuous operation. The cell growth in the batch suspension culture followed the Monod kinetics with sucrose as a primary substrate while the production of gossypol followed the Leudeking-Piret equation. Permeabilization was used as a means to releasing secondary metabolites from plant cells. Permeabilization of immobilized cells provided a tool for a continuous process increasing release of gossypol by 30%, while the elicitation technique played a major role in enhancing productivity more than 8-fold. G. arboreum cells were effectively immobilized on cotton matrix by entrapment with a spirally wound configuration. In comparisons of productivity, continuous operation and combined treatment gave over 20-fold higher productivity than batch culture. Simultaneous use of immobilization, permeabilization, and elicitation was possible in continuous operation with an immobilized plant cell reactor. The proposed models of permeabilization and elicitation took into accounts the effect of DMSO and/or elicitor addition on growth and production. The elicitation model explained the secondary metabolite production as a series reaction of signal transduction, mRNA synthesis, enzyme synthesis, and product formation. An axial dispersion model was suggested to explain the behavior of the immobilized plant cell reactor. The models proposed here showed good fit to experimental data.
Degree
Ph.D.
Advisors
Okos, Purdue University.
Subject Area
Agricultural engineering|Plant propagation
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