Kinetics of phosphate limited growth of poppy plant suspension cultures

Wayne Roger Curtis, Purdue University

Abstract

To evaluate the economic feasibility of large scale production of morphinan alkaloids by P. somniferum suspension cultures, the growth kinetics must be determined. The effect of initial sucrose, inorganic salts, and phosphate on batch growth were studied. Growth kinetics were shown to be phosphate limited and an intracellular conserved substrate growth model was developed to predict batch growth profiles based only upon initial conditions of the inoculum. An extensive literature review indicates that the model should be applicable to the phosphate limited growth of algae and bacteria as well. Continuous culture was evaluated as a technique for the study of plant suspensions culture under well defined conditions. Based on the slow growth, large aggregate size, and rapid aggregate sedimentation velocities of plant cells in suspension, chemostatic culture was shown to require the use of bioreactors of volumes of 10 liters or more to avoid effluent stream separation. Semi-continuous and intermittent effluent culture methods were evaluated as alternatives to approximate continuous culture. Use of semi-continuous culture is hampered by relatively large fluctuations in nutrient levels. Intermittent effluent culture which utilizes intermittent fed-batch intervals as long as 48 hours, provides a small scale experimental system for plant suspension cultures that provides an essentially constant specific growth rate without the problems associated with "true" chemostatic culture. The rheology of a large number of plant suspension cultures was examined. The common perception of highly viscous non-Newtonian behavior for plant suspensions has been shown to be invalid.

Degree

Ph.D.

Advisors

Emery, Purdue University.

Subject Area

Chemical engineering

COinS