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

• Published in: Separation and purification technology Vol. 95; pp. 216 - 221
• Main Authors: Sun, Min, Li, Wen-Wei, Mu, Zhe-Xuan, Wang, Hua-Ling, Yu, Han-Qing, Li, Yu-You, Harada, Hideki
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 19.07.2012; Elsevier
• Subjects: Applied sciences; Bacillus megaterium; Bacteria; Chemical engineering; EDTA; EPS; Exact sciences and technology; Extracellular polymeric substances (EPSs); Extraction; Flocculating; Flocculation activity; Microorganisms; Separation; Ultrasonic testing; Extracellular polymeric substances (EPSs); Extraction; Separation; Flocculation activity; Bacillus megaterium; Sonication; Stabilization; Extract; Heating; Flocculation; Biofilm; Disruption; Granule; Ultrasound
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2012.05.010

► Six methods were applied to extract EPS from Bacillus megaterium TF10. ► Flocculation activity of EPS was used to quantitatively evaluate EPS disruption. ► The extraction performance of the six methods was comprehensively evaluated. 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, H2SO4, 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 H2SO4 methods lead to a high EPS yield compared to the ultrasonication or EDTA methods, while the ultrasonication and H2SO4 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 (10h), 92.2%>heating (120min), 91.6%>glutaraldehyde (15min), 90.9%>ultrasonication (30min), 81.0%>H2SO4 (45min), 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 10h was identified to be most effective method to extract EPS from B. megaterium TF10.