Purification and partial characterisation of pectin methylesterase produced by Fusarium asiaticum

Fusarium asiaticum is the predominant causal agent of Fusarium head blight (FHB) in China. When grown in liquid cultures containing potato tuber extract as the sole carbon source, F. asiaticum (strain 7071) from wheat (China) produced pectin methylesterase (PME), polygalacturonase (PG), and pectin lyase (PNL). The activity of these pectolytic enzymes was detected by a gel diffusion assay. Three forms of PME were identified in a culture filtrate of F. asiaticum. Two forms of PME with molecular weights of 31 kDa and 42.5 kDa, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), were purified using a combination of chromatographic techniques. These PMEs did not bind to Concanavalin A (Con A), which was confirmed by rechromatography using a Con A agarose column. The 31 kDa purified PME was thermostable in a temperature range of 25-55 °C. The optimal pH for the PME of F. asiaticum was 6.5. This research provides the basis for future investigations of pectolytic enzymes from F. asiaticum.