Extraction of extracellular polymeric substances (EPS) from red soils (Ultisols)

Extracellular polymeric substances (EPS) have many beneficial functions in soils. Accurate quantification of EPS in soils is crucial. Here, five methods were compared for their suitability for extraction of EPS from Ultisols: hot water extractable polysaccharide (HWEP), hot dilute acid extractable polysaccharide (HDAEP), easily extractable glomalin (EEG), sodium sulfide (SS) and cation exchange resin (CER) method. Humic-acid equivalent (HAE) was used as an indicator for extracellular contamination and ATP for quantifying intracellular contamination from cell lysis. Among the tested methods, CER resulted in EPS extraction with minimal contamination. Therefore, we propose that CER is currently the most appropriate method for extraction of EPS from Ultisols.