Selection of effective methods for extracting extracellular polymeric substances (EPSs) from Bacillus megaterium TF10

Min Sun, Wen Wei Li, Zhe Xuan Mu, Hua Ling Wang, Han Qing Yu, Yu You Li, Hideki Harada

Research output: Contribution to journalArticlepeer-review

51 Citations (Scopus)


Bacterial extracellular polymeric substances (EPSs) play an important role in the formation and stabilization of bioaggregates, such as biofilm, microbial flocs and granules. Thus, the selection of appropriate extraction method is of critical importance, which may affect the yield, compositions and properties of EPS. In this work, six different methods used for EPS extraction, including ultrasonication, heating, formaldehyde + NaOH, H 2SO 4, glutaraldehyde, and EDTA methods, from Bacillus megaterium TF10, a bacterium with a high EPS-producing capacity isolated from a soil sample, are investigated. These EPS extraction methods are compared in terms of EPS yields and compositions, cell lysis, and flocculation activities and spectrum characteristics of extracted EPS. The results show that both EPS yield and cell lysis generally increase with the extraction time. The heating, formaldehyde + NaOH and H 2SO 4 methods lead to a high EPS yield compared to the ultrasonication or EDTA methods, while the ultrasonication and H 2SO 4 methods cause much more cell lysis than the formaldehyde + NaOH treatment. The flocculation activities of EPS, which can quantitatively reflect the EPS disruption during extraction, are also evaluated. The flocculation efficiencies of the extracted EPS are found in the order of: formaldehyde + NaOH (30-min formaldehyde treatment and then 60-min NaOH treatment), 92.4% > EDTA (10 h), 92.2% > heating (120 min), 91.6% > glutaraldehyde (15 min), 90.9% > ultrasonication (30 min), 81.0% > H 2SO 4 (45 min), 73.2% > control, 59.9%. The IR and EEM spectra suggest that the EPS compositions and structures also vary significantly with the extraction method. Among the six methods, the EDTA method with an extraction time of 10 h was identified to be most effective method to extract EPS from B. megaterium TF10.

Original languageEnglish
Pages (from-to)216-221
Number of pages6
JournalSeparation and Purification Technology
Publication statusPublished - 2012 Jul 19


  • Bacillus megaterium
  • Extracellular polymeric substances (EPSs)
  • Extraction
  • Flocculation activity
  • Separation


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