Ion chromatographic analysis of nutrients in seed exudate for microbial colonisation

Information on the composition, levels, availability and microbial utilisation of the nutrients present in root and seed exudates is invaluable in harnessing selected microbes as biocontrol agents. The complex matrix that is sugar beet seed exudate is examined utilising the chromatographic modes of ion-exclusion-partition and ion-exchange. Many of the carbohydrates, organic acids and inorganic anions present there are identified, Specifically, collected seed exudate samples are analysed on an Aminex HPX-87H cation-exchange chromatography column with a dilute sulphuric acid mobile phase and refractive index detection. Improved resolution for the organic acids present (succinate, oxalate, formate, acetate) is achieved by a pre-treatment extraction on SAX cartridges prior to this chromatographic analysis. The inorganic anions fluoride, chloride, nitrate, phosphate and sulphate are directly determined alongside oxalate by ion chromatography on a Dionex IonPac AS4A column with isocratic elution and suppressed conductivity detection. In addition, the sugars (galactose, glucose, mannose, lactose, raffinose, maltose) can be analysed by high-performance anion-exchange chromatography with pulsed amperometric detection. (C) 1998 Elsevier Science B.V.