(38d) An Improved Temporary Immersion Bioreactor for Plant Tissue Culture Propagation

A bioreactor system has been fabricated for plant tissue culture propagation which utilizes low-cost plastic bags combined with gravity driven flows as an approach to achieving scale-up.  These temporary immersion bioreactors (TIB) provide for complete media-tissue contacting while minimizing boundary layer mass-transfer resistances and water-logging the plant tissue.  Media flow to and from the bioreactor is facilitated via stepper motors interfaced to a computer with LabVIEW.   LabVIEW has also provided a means to monitor the reactors over the web were time-lapse videos are created from periodic images captured by web cam.  This automation has been critically important to development activities since monitoring is required every 6 hours for 8-week bioreactor runs.  Seedless watermelon propagation has been carried out where the TIB-grown tissue generates a statistically indistinguishable amount of tissue as compared to solid agar culture controls.  While experiments have shown more ‘unhealthy’ tissue in the bioreactor, this is believed to be due to periodic flow problems during prototype trouble-shooting.  Ongoing studies utilize tobacco root tissue culture which grows nearly an order of magnitude faster than watermelon,  and will allow rapid trouble-shooting and more discernible comparisons of mass transfer and mixing limitations.  The goal of this research is to develop technology that will speed up plant improvement programs including an ongoing effort to develop disease resistant cacao (chocolate tree).