The Role of Extracellular Polymeric Substances in the Toxicity Response of Anaerobic Granule Sludge to Different Metal Oxide Nanoparticles

Li, Huiting; Chang, Fang; Li, Zhendong; Cui, Fuyi

doi:10.3390/ijerph19095371

Cited by 5 publications

(2 citation statements)

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“…EPS mainly contain polymers like polysaccharides, proteins and humic acids, and enclose cells in a matrix by electrostatic and hydrophobic interactions ( Henriques and Love, 2007 ). EPS contain charged functional side groups and thus enable ligation to other charged molecules ( Li et al, 2022 ). PAA (pKa = 4.31), PPA (pKa = 4.66) and PBA (pKa = 4.67) are mainly dissociated in water at neutral to slightly alkalic pH ( Supplementary Tables S1–S4 ); therefore, phenyl acids could have been effectively bound to EPS.…”

Section: Discussionmentioning

confidence: 99%

Effects of phenyl acids on different degradation phases during thermophilic anaerobic digestion

et al. 2023

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Aromatic compounds like phenyl acids (PA) can accumulate during anaerobic digestion (AD) of organic wastes due to an increased entry of lignocellulose, secondary plant metabolites or proteins, and thermodynamic challenges in degrading the benzene ring. The effects of aromatic compounds can be various – from being highly toxic to be stimulating for methanogenesis – depending on many parameters like inoculum or molecular characteristics of the aromatic compound. To contribute to a better understanding of the consequences of PA exposure during AD, the aim was to evaluate the effects of 10 mM PA on microbial communities degrading different, degradation phase–specific substrates in thermophilic batch reactors within 28 days: Microcrystalline cellulose (MCC, promoting hydrolytic to methanogenic microorganisms), butyrate or propionate (promoting syntrophic volatile fatty acid (VFA) oxidisers to methanogens), or acetate (promoting syntrophic acetate oxidisers to methanogens). Methane production, VFA concentrations and pH were evaluated, and microbial communities and extracellular polymeric substances (EPS) were assessed. The toxicity of PA depended on the type of substrate which in turn determined the (i) microbial diversity and composition and (ii) EPS quantity and quality. Compared with the respective controls, methane production in MCC reactors was less impaired by PA than in butyrate, propionate and acetate reactors which showed reductions in methane production of up to 93%. In contrast to the controls, acetate concentrations were high in all PA reactors at the end of incubation thus acetate was a bottle-neck intermediate in those reactors. Considerable differences in EPS quantity and quality could be found among substrates but not among PA variants of each substrate. Methanosarcina spp. was the dominant methanogen in VFA reactors without PA exposure and was inhibited when PA were present. VFA oxidisers and Methanothermobacter spp. were abundant in VFA assays with PA exposure as well as in all MCC reactors. As MCC assays showed higher methane yields, a higher microbial diversity and a higher EPS quantity and quality than VFA reactors when exposed to PA, we conclude that EPS in MCC reactors might have been beneficial for absorbing/neutralising phenyl acids and keeping (more susceptible) microorganisms shielded in granules or biofilms.

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Section: Discussionmentioning

confidence: 99%

Effects of phenyl acids on different degradation phases during thermophilic anaerobic digestion

et al. 2023

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“…In a metal-rich environment, extracellular polymeric substance (EPS) production is part of a stress-response mechanism to support 10.3389/fmicb.2023.1233221 Frontiers in Microbiology 04 frontiersin.org the cell in reducing the metal ions availability, by chelation and sequestration as an ion exchange matrix. The EPS matrix behaves like a gel-like grid that keeps microbial cells together, supporting biofilms' adhesion on surfaces and protecting the cells from extreme environments (van Wolferen et al, 2018;Li et al, 2022;Wang et al, 2022). Carboxyl, hydroxyl, sulfate, phosphoryl, and amino groups of protein in EPS are responsible for metals biosorption (Torres, 2020).…”

Section: S-layer and Eps Mediated Metal Cation Removal Via Biosorptio...mentioning

confidence: 99%

Perspective on the use of methanogens in lithium recovery from brines

et al. 2023

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Methanogenic archaea stand out as multipurpose biocatalysts for different applications in wide-ranging industrial sectors due to their crucial role in the methane (CH4) cycle and ubiquity in natural environments. The increasing demand for raw materials required by the manufacturing sector (i.e., metals-, concrete-, chemicals-, plastic- and lubricants-based industries) represents a milestone for the global economy and one of the main sources of CO2 emissions. Recovery of critical raw materials (CRMs) from byproducts generated along their supply chain, rather than massive mining operations for mineral extraction and metal smelting, represents a sustainable choice. Demand for lithium (Li), included among CRMs in 2023, grew by 17.1% in the last decades, mostly due to its application in rechargeable lithium-ion batteries. In addition to mineral deposits, the natural resources of Li comprise water, ranging from low Li concentrations (seawater and freshwater) to higher ones (salt lakes and artificial brines). Brines from water desalination can be high in Li content which can be recovered. However, biological brine treatment is not a popular methodology. The methanogenic community has already demonstrated its ability to recover several CRMs which are not essential to their metabolism. Here, we attempt to interconnect the well-established biomethanation process with Li recovery from brines, by analyzing the methanogenic species which may be suitable to grow in brine-like environments and the corresponding mechanism of recovery. Moreover, key factors which should be considered to establish the techno-economic feasibility of this process are here discussed.

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