ABSTRACT
A kinetic metabolic model describing Catharanthus roseus hairy root growth and nutrition was developed. The metabolic network includes glycolysis, pentose-phosphate pathway, TCA cycle and the catabolic reactions leading to cell building blocks such as amino acids, organic acids, organic phosphates, lipids and structural hexoses. The central primary metabolic network was taken at pseudo-steady state and metabolic flux analysis technique allowed reducing from 31 metabolic fluxes to 20 independent pathways. Hairy root specific growth rate was described as a function of intracellular concentration in cell building blocks. Intracellular transport and accumulation kinetics for major nutrients were included. The model uses intracellular nutrients as well as energy shuttles to describe metabolic regulation. Model calibration was performed using experimental data obtained from batch and medium exchange liquid cultures of C. roseus hairy root using a minimal medium in Petri dish. The model is efficient in estimating the growth rate.
Subject(s)
Catharanthus/physiology , Energy Metabolism/physiology , Multienzyme Complexes/metabolism , Plant Proteins/metabolism , Plant Roots/physiology , Cell Culture Techniques/methods , Cell Proliferation , Kinetics , Metabolic Clearance Rate , Models, BiologicalABSTRACT
Two direct HPLC analytical methods for the screening of the major indole alkaloids of Catharanthus roseus hairy roots and their iridoid precursors have been developed. Photodiode array and fluorescence detection were performed. The separation was achieved on a reversed-phase C18 column. The first method allowed the separation of catharanthine, serpentine, tabersonine, vindoline, vinblastine, and vincristine in 20 min. Ajmalicine, tryptophan, tryptamine and secologanine were separated using the second method in 13 min. The identification of the compounds was based on the retention time and the comparison of UV spectra with those of authentic standards. A simplified alkaloid extraction method was developed in order to accelerate sample preparation. The assays were successfully used to quantify major compounds of the secondary metabolism of hairy root cultures of C. roseus, thus providing a reliable tool for rapid screening of C. roseus secondary metabolite samples. In these cultures, ajmalicine, serpentine, catharanthine, tabersonine, and tryptamine were detected, but tryptophan, vindoline, vinblastine and vincristine were not.
