Alteration of the characteristics of extracellular polymeric substances (EPS) extracted from the fungus Phanerochaete chrysosporium when exposed to sub-toxic concentrations of nickel (II)

• Published in: International biodeterioration & biodegradation Vol. 129; pp. 179 - 188
• Main Authors: Cao, Feishu, Bourven, Isabelle, Guibaud, Gilles, Rene, Eldon R., Lens, Piet N.L., Pechaud, Yoan, van Hullebusch, Eric D.
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.04.2018; Elsevier BV; Elsevier
• Subjects: Biomass; Cell surface; Chemical and Process Engineering; Engineering Sciences; EPS; Fluorescence; Fourier transforms; Functional groups; Fungi; Hydrophobic surfaces; Hydrophobicity; Hydroxyl groups; Immobilization; Infrared analysis; Infrared spectroscopy; Molecular chains; Molecular size; Molecular weight; Nickel; Phanerochaete chrysosporium; Polysaccharides; Proteins; Fungi; EPS; Nickel; Molecular size; Hydrophobicity; Phanerochaete chrysosporium
• ISSN: 0964-8305; 1879-0208
• DOI: 10.1016/j.ibiod.2018.02.009

The fungus Phanerochaete chrysosporium was incubated at five sub-toxic concentrations of Ni2+ (0.5, 1, 5, 10 and 25 mg/L, respectively), and its metal immobilization ability as well as the alteration of some characteristics regarding the extracellular polymeric substances (EPS) were investigated. With the increased Ni2+ concentrations in the broth, higher Ni2+ amounts were measured in both intact fungal cells (biomass before EPS extraction) and EPS-free biomass (biomass after EPS extraction). The Ni2+ immobilization ability of the extracted EPS displayed a similar level at Ni2+ concentrations higher than 1 mg/L. The presence of Ni2+ in the broth decreased the zeta-potential of the intact biomass and increased cell surface hydrophobicity (CSH). Fourier transform infrared spectroscopy (FT-IR) analyses identified the presence of some functional groups, such as carboxyl, phosphoryl and hydroxyl groups, in the extracted EPS. The high hydrophobicity (>60%) of the extracted EPS was decreased by the increased Ni2+ concentration. The protein (PN) and polysaccharide (PS) content in the EPS was also affected by the increased Ni2+ concentration, and the abundance of PN-like molecules ranging from 0.5 kDa to 14 kDa was enriched. However, the fluorescence characteristics and apparent molecular weight (aMW) of the extracted EPS were not affected by the Ni2+ concentration. Therefore, one possible defense mechanism developed by the fungus towards Ni2+ stress is the adjustment of its EPS composition. •The nickel immobilization ability of the extracted fungal EPS maintained a similar level at Ni2+ concentrations higher than 1 mg/L.•Fluorescence spectra and apparent molecular weight distribution of the fungal EPS exhibited similar features, regardless the Ni2+ concentration.•Zeta-potential and EPS hydrophobicity gradually decreased when the Ni2+ concentration increased.•Protein and polysaccharide content in the extracted EPS demonstrated an opposite trend when increasing the Ni2+ concentration.