Researchers from the Institute of Process Engineering, Chinese Academy of Sciences (CAS-IPE) explained the possible mechanism on ultrasound-intensified hairy root culture of E. purpurea in the paper published on Biotechnology Progress.

Prof. LIU Chunzhao’s group from IPE has done a series of researches on ultrasound-intensified process. In their earlier work, they established a two-dimensional axisymmetric computational fluid dynamics (CFD) model based on a porous media model and a discrete population balance model. During the hairy root culture of E.chinacea purpurea, the hydrodynamics and oxygen mass transfer in the bioreactor were simulated by this CFD model. Membrane permeability, dissolved oxygen concentration and phenylalanine ammonium lyase activity were measured in the work.

Simulative results indicated that liquid flow and turbulence played a dominant role in oxygen mass transfer in the growth domain of the hairy root culture. And ultrasound intensified oxygen mass transfer in hairy root clump, which caused root growth and cichoric acid biosynthesis simulation.

The dissolved oxygen concentration in the hairy root clump increased from the bottom to the top of the bioreactor cultured with the hairy roots, which was verified by the experimental detection of dissolved oxygen concentration in the hairy root clump.

In the ultrasound field, hairy root membrane permeability increased. PAL activity showed good correlation to cichoric acid accumulation in the hairy roots of E. purpurea.

This methodology provided insight understanding on the complex system of hairy root culture and will help to eventually guide the bioreactor design and process intensification of large-scale hairy root culture.