Evaluation of growth property of red beet hairy roots depending on condition of inocula and its application to culture control with fuzzy logic theory

The influence of period of preculture on growth was examined for the development of control system suitable to the culture of red beet hairy roots. The prolongation of preculture caused the decrease in viability of root tips, resulting in the extension of lag phase during the following culture. The number of lateral roots emerging from the inoculated hairy roots could be used as a parameter for the identification of the culture phases. A bioreactor system including a solid-culture unit to monitor the variation in the number of growing points (GPs) was constructed, and the fuzzy inferencing was employed for the control of shear stress in the culture, based on the membership functions with state variables concerning the growth indexes in terms of the number of GPs and concentration of cell mass. The successful performances were achieved by means of appropriate recognition of culture phases in the cultures of hairy roots with different levels of tip viability. It was verified that this control system could be available for the culture with variation of inoculum states by employing the state variable based on the number of elongating tip meristems of the hairy roots. (C) 2001 Elsevier Science B.V. All rights reserved.