Comparison of extraction methods for extracellular polymeric substances (EPS) and dynamic characterization of EPS from sessile microorganisms during pyrite bioleaching. Issue 3 (June 2022)

• Record Type: Journal Article
• Authors: Shen, Li; Cheng, Jinju; Wang, Junjun; Cui, Linlin; Zhang, Yejuan; Liao, Wanqing; Liu, Zhiru; Zhou, Hao; Wu, Xueling; Li, Jiaokun; Zeng, Weiming
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 3(2022)
• Publication Date: 2022-06
• Subjects: Extracellular polymeric substances -- Pyrite bioleaching -- Extraction methods -- Confocal laser scanning microscope; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.107922
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Extracellular polymeric substances (EPS) have many beneficial functions in the bioleaching process. A mixed culture of moderate thermophilic microorganisms was used to bioleach pyrite concentrate in a stirred tank reactor at a pulp density of 6%. Three physical methods (heating, ultrasound and vibration with glass beads) and three chemical methods (NaOH, H2 SO4 and formaldehyde) were assessed for the extraction of EPS from sessile microorganisms. The parameter conditions for each method were optimised to obtain the optimal settings. The EPS content of each extract varied depending on the extraction method used. Cell lysis can be minimised by optimizing the extraction conditions. Results indicated that heating method outperformed other methods with low cell lysis and yielded 355.56 ± 116.56 ug/10 8 cells of protein and 16.72 ± 1.45 ug/10 8 cells of polysaccharides. Thereafter, this method was applied to extract EPS from pyrite surface during the bioleaching process. During pyrite bioleaching, extracellular proteins were the major component of EPS extracted from sessile strains. Confocal laser scanning microscope and scanning electron microscope showed that pyrite grains were wrapped by many extracellular proteins. Therefore, this research can provide a reference for the extraction of EPS from moderate thermophilic bioleaching systems by analysing the potential impact of extraction methods. Highlights: ● The optimal parameters of six physical/chemical methods for extracting EPS from sessile microorganisms was explored. ● Extraction with heating method was effective for EPS developed. ● The relevance of EPS secretion to improve understanding of bioleaching process is discussed.