ION-CHROMATOGRAPHIC ANALYSIS OF NUTRIENTS IN SEED EXUDATE FOR MICROBIAL COLONIZATION

Information on the composition, levels, availability and microbial uti lisation of the nutrients present in root and seed exudates is invalua ble in harnessing selected microbes as biocontrol agents. The complex matrix that is sugar beet seed exudate is examined utilising the chrom atographic modes of ion-exclusion-partition and ion-exchange. Many of the carbohydrates, organic acids and inorganic anions present there ar e identified, Specifically, collected seed exudate samples are analyse d on an Aminex HPX-87H cation-exchange chromatography column with a di lute sulphuric acid mobile phase and refractive index detection. Impro ved resolution for the organic acids present (succinate, oxalate, form ate, acetate) is achieved by a pre-treatment extraction on SAX cartrid ges prior to this chromatographic analysis. The inorganic anions fluor ide, chloride, nitrate, phosphate and sulphate are directly determined alongside oxalate by ion chromatography on a Dionex IonPac AS4A colum n with isocratic elution and suppressed conductivity detection. In add ition, the sugars (galactose, glucose, mannose, lactose, raffinose, ma ltose) can be analysed by high-performance anion-exchange chromatograp hy with pulsed amperometric detection. (C) 1998 Elsevier Science B.V.