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Liquid Culture Systems for in vitro Plant Propagation

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Chapter 2<br />

Application of bioreactor design pr<strong>in</strong>ciples to plant<br />

micropropagation<br />

Wayne R. Curtis<br />

The Pennsylvania State University, Department of Chemical Eng<strong>in</strong>eer<strong>in</strong>g.<br />

Address <strong>for</strong> Correspondence: 108 Fenske Laboratory, Dept. of Chemical Eng<strong>in</strong>eer<strong>in</strong>g,<br />

University Park, PA 16802-4400, USA. Phone:1-(814)863-4805, Fax:1-(814) 865-7846,<br />

E-mail: WRC2@PSU.EDU<br />

Abstract: Pr<strong>in</strong>ciples of oxygen consumption, oxygen transport, suspension, and mix<strong>in</strong>g are<br />

discussed <strong>in</strong> the context of propagat<strong>in</strong>g aggregates of plant tissue <strong>in</strong> liquid suspension<br />

bioreactors. Although micropropagated plants have a relatively low biological oxygen<br />

demand (BOD), the relatively large tissue size and localization of BOD <strong>in</strong> meristematic<br />

regions will typically result <strong>in</strong> oxygen mass transfer limitations <strong>in</strong> liquid culture. In contrast<br />

to the typical focus of bioreactor design on gas-liquid mass transfer, it is shown that mediasolid<br />

mass transfer limitations limit oxygen available <strong>for</strong> aerobic plant tissue respiration.<br />

Approaches to improve oxygen availability through gas supplementation and bioreactor<br />

pressurization are discussed. The <strong>in</strong>fluence of media components on oxygen availability are<br />

also quantified <strong>for</strong> plant culture media. Experimental studies of polystyrene beads <strong>in</strong><br />

suspension <strong>in</strong> a 30-litre air-lift and stirred bioreactors are used to illustrate design pr<strong>in</strong>ciples<br />

<strong>for</strong> circulation and mix<strong>in</strong>g. Potential limitations to the use of liquid suspension culture due to<br />

plant physiological requirements are acknowledged.<br />

Key words: oxygen transport, respiration, somatic embryogenesis, suspension culture, tissue<br />

culture<br />

Abbreviations: see ‘List of nonstandard units’, ‘List of variables’ and ‘Greek symbols’<br />

A.K. Hvoslef-Eide and W. Preil (eds.), <strong>Liquid</strong> <strong>Culture</strong> <strong>Systems</strong> <strong>for</strong> <strong>in</strong> <strong>vitro</strong> <strong>Plant</strong> <strong>Propagation</strong>, 21–40.<br />

© 2005 Spr<strong>in</strong>ger. Pr<strong>in</strong>ted <strong>in</strong> the Netherlands.<br />

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