•EPS-C, N, P preferentially retained during adsorption and coprecipitation with Fh.•EPS mass uptake and selective fractionation opposite for the two formation pathways.•Proteins and acidic ...polysaccharides selectively retained in adsorption complexes.•Lipids and polysaccharide components selectively retained in coprecipitates.•Differential sorption process of EPS components with Fh revealed by 2D-COS-FTIR.
Recent work shows that microbially-derived compounds constitute a significant fraction of the soil organic matter (OM) pool. These compounds include extracellular polymeric substances (EPS) whose mass can far exceed total microbial cell biomass. Sorption of EPS to soil minerals occurs via adsorption and coprecipitation and contributes to the preservation of OM in the soil environment. Little is known, however, about the sorption mechanisms of EPS and selective retention of different EPS constituents on iron (oxyhydr)oxides, especially during EPS adsorption versus coprecipitation with these reactive soil phases. This study examines how EPS interacts with the ubiquitous soil iron (oxyhydr)oxide ferrihydrite during EPS adsorption and coprecipitation and whether these different EPS-mineral association pathways affect EPS sorption and selective retention, and thus the mobility and fate of microbially-derived OM in the soil environment. We use several complimentary techniques to i) examine EPS-carbon, EPS-nitrogen and EPS-phosphorus sorption and fractionation, ii) visualize spatial relationships between EPS biomolecular classes and ferrihydrite using confocal laser scanning microscopy (CLSM), iii) determine EPS-C speciation and chemical fractionation with ferrihydrite using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and iv) determine functional group interactions with ferrihydrite using Fourier transform infrared spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy (2D-COS) analysis. Results show that the coprecipitation of EPS does not change the ferrihydrite mineralogy, as the main mineral phase for EPS association, but it substantially increases the particle size of EPS-ferrihydrite. A substantial difference in the EPS mass fraction associated with the ferrihydrite is observed between the adsorption and coprecipitation experiments at an initial molar C/Fe ratio >1. The EPS-N is relatively enriched during the adsorption process, while more EPS-C and near-complete EPS-P are fixed in the coprecipitation process. XPS results show that the surface of the ferrihydrite formed through EPS adsorption is preferentially enriched with protein-like components, whereas, the surface of the ferrihydrite formed through EPS coprecipitation is enriched with polysaccharide-like components, which is visually confirmed with CLSM images. NEXAFS results reveal that the carboxylic/amide C-containing components are selectively retained during adsorption, with the aliphatic and O-alkyl C-containing components relatively enriched during coprecipitation. 2D-FTIR-COS results indicate that during EPS adsorption on ferrihydrite the PO functional groups are adsorbed faster than the amide and carboxylate functional groups, while during EPS coprecipitation with ferrihydrite the opposite trend is observed. The findings from this study indicate that the formation pathway of EPS-ferrihydrite associations substantially effects the sorption mechanisms and selective retention of EPS and may thus affect the mobility and fate of microbially-derived carbon (C), nitrogen (N) and phosphorus (P) in soils. These new insights on EPS behaviour at the mineral–water interface might be used to evaluate how microbially-derived compounds like EPS are stabilized by iron (oxyhydr)oxides and how EPS-iron (oxyhydr)oxide couplings might affect the reactivity and cycling of OM in natural environments.
Opposite to the significant knowledge about the toxicity of AgNPs to phytoplankton species, rather limited knowledge is available about the role of phytoplankton secretions such as extracellular ...polymer substances (EPS) in NPs’ fate ...
This study determined the impact of changes in the Jakarta Islamic Index's Consumer Goods sector's Earnings Per Share, Return on Equity, and Gross Domestic Product from 2018 to 2020. This work uses ...panel data regression analysis and quantitative research techniques with secondary data. A purposive sampling method, or sample selection strategy based on several variables, was employed to choose the sample of firms in the consumer goods sector represented in the JII index. The F test results indicate that from 2018 to 2020, GDP, EPS, and ROE can impact the share price of JII issuers. According to the T-test, only EPS may have an enormous positive impact on stock prices, whereas ROE has a significant negative effect. GDP demonstrates that from 2018 to 2020, firms' stock prices in the consumer goods sector listed on JII are unaffected by GDP.
Enhanced biological phosphorus removal (EBPR) process is known to mainly rely on the ability of phosphorus-accumulating organisms to take up, transform and store excess amount of phosphorus (P) ...inside the cells. However, recent studies have revealed considerable accumulation of P also in the extracellular polymeric substances (EPS) of sludge, implying a non-negligible role of EPS in P removal by EBPR sludge. However, the contribution of EPS to P uptake and the forms of accumulated extracellular P vary substantially in different studies, and the underlying mechanism of P transformation and transportation in EPS remains poorly understood. This review provides a new recognition into the P removal process in EBPR system by incorporating the role of EPS. It overviews on the characteristics of P accumulation in EPS, explores the mechanism of P transformation and transportation in EBPR sludge and EPS, summarizes the main influential factors for the P-accumulation properties of EPS, and discusses the remaining knowledge gaps and needed future efforts that may lead to better understanding and use of such an EPS role for maximizing P recovery from wastewater.
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•An updated overview on the characteristics of P accumulation in EPS is provided.•Mechanisms of P transformation and transportation in sludge and EPS are explored.•Main influential factors on the P-accumulation properties of EPS are analyzed.•Remaining knowledge gaps and needed future efforts are highlighted.
Sewage sludge (mainly composed of excessive bio-sludge) is an inevitable by-product of biological wastewater treatment process and contains various toxic substances, such as pathogens, heavy metals, ...and organic contaminants. The production of sewage sludge may cause serious pollution risks without appropriate disposals. As the essential step of sludge treatment, dewatering plays significant roles in minimizing the sludge volume, facilitating the transportation, increasing the calorific value and even reducing the leachate production in landfill sites. This paper presents a comprehensive review on the issues related to dewatering of sewage sludge. Section 1 starts with the environmental implications of sludge dewatering. Section 2 deals with the concepts and challenges about differentiation of bound water fractions, and also reviews the recent progress of in-situ visualization of water occurrence states in bio-flocs. Section 3 discusses about how various physiochemical properties influence the sludge dewaterability, and the insufficiency in in-situ micro-characterization of sludge constituents is pointed out. Section 4 reviews the existing conditioning technologies for sludge dewaterability improvement, and the advantages/disadvantages of each technology in terms of applicable occasions, material consumption, energy consumption and environmental impacts are evaluated. The last section (section 5) specifically analyzes the feasibility of integrating sludge dewatering and re-utilization, and raises attention to the potential environmental risks of dewatering conditioning. Based on the above discussion, we propose that a unified theory for sludge dewaterability improvement remains to be established. Especially, how the molecular structures of sludge compositions affect the solid-water interface behavior requires to be deepened, which will further unravel the mechanism behind strong water-holding capacities of bio-flocs. Additionally, we believe that the key challenges for sludge dewatering is how to select the appropriate conditioning technique according to the physiochemical properties of target sludge. The reliable indicators for real-time control of conditioning operations are still deficient, e.g., dynamic dosage control of conditioning chemicals. Accordingly, the potential environmental risks of excessive conditioning chemicals should be taken into more consideration.
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•Sludge dewaterability improvement is reviewed from fundamentals to implementations.•Challenges and recent advances in water differentiation of bio-sludge are discussed.•Micro-mechanism analysis on water binding behavior of bio-sludge is insufficient.•Impacts of conditioning operation on sludge utilization should be seriously examined.
•nZVI promoted the removal efficiency of the anammox reactor.•Addition of nZVI improved the AnAOB abundance from 42.1% to 52.5%.•nZVI increased the c-di-GMP synthesized protein from 148 rpmr to 252 ...rpmr.•nZVI decreased the c-di-GMP degradation protein from 238 rpmr to 204 rpmr.•Enrichment of c-di-GMP is beneficial to the formation of sludge particles.
The addition of nano zero-valent iron (nZVI) has been proven to improve the efficiency of the anammox process, however, the mechnism is not clear. Here, the effect of nZVI on anammox microbial community was studied by metagenomic sequencing methods. It was found that 50 mg/L nZVI indeed promoted the removal of NH4+ and NO2− of the anammox reactor and significantly improved the relative abundance of AnAOB (Ca. Brocadia) from 42.1% to 52.5%. What's more, 50 mg/L nZVI increased the abundance of c-di-GMP synthesized protein from 148 rpmr to 252 rpmr in the microbial community and decreased the abundance of c-di-GMP degradation protein from 238 rpmr to 204 rpmr, which indirectly led to the enrichment of c-di-GMP in the microbial community. The enrichment of c-di-GMP reduced the motility of microorganisms in the reactor and promoted the secretion of extracellular polymers by bacteria, which is beneficial to the formation of sludge particles in the anammox reactor. In conclusion, this research clarified the mechanism of nZVI promoting the anammox process and provided theoretical guidance for the engineering application of anammox.
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•A novel exopolysaccharide (R-5-EPS) was obtained from Lactobacillus helveticus LZ-R-5.•R-5-EPS was a linear hetero-glucogalactan with average Mw of 5.41 × 105 Da.•Structure of ...R-5-EPS was composed of →3)-β-D-Glcp-(1→ and →6)-β-D-Galp-(1→ residues.•R-5-EPS showed potent macrophage immunomodulatory activity in vitro.
Exopolysaccharide (R-5-EPS) was isolated from the fermented milk of Lactobacillus helveticus LZ-R-5 and purified by DEAE-52 cellulose anion-exchange column, and characterization of the structure was conducted. Results showed that R-5-EPS was a heteropolysaccharide containing linear repeating units of →6)-β-D-Galp-(1→3)-β-D-Glcp-(1→3)-β-D-Glcp-(1→3)-β-D-Glcp-(1→3)-β-D-Glcp-(1→ with an average Mw of 5.41 × 105 Da. Furthermore, at a cellular level, R-5-EPS showed immunostimulatory activity due to its strong effect on increasing proliferation of RAW264.7 macrophages and enhancing phagocytosis, acid phosphatase activity, nitric oxide production and cytokines production in macrophages. These results suggest that R-5-EPS have a potent immunostimulatory activity and may be explored as a potential immunomodulatory agent.
Microbially secreted exopolymeric substances (EPS), rich in polysaccharides and proteins, make up an important part of natural organic matter in the ocean, especially marine snow. While the attention ...in the oceanographic literature is focused more on the role of polysaccharides and less of proteins in EPS functions, the role of proteins, especially the role of the protein/carbohydrate (P/C) ratio of particles and colloids (macromolecular fraction) remains to be explored. EPS associated with particles forms a biofilm, where proteins are not only involved in cell surface attachment, but also in the stabilization of the biofilm matrix, and the development of a three-dimensional biofilm architecture. Here, we provide a perspective based on the most recent literature on EPS, marine oil spills and waste water treatment to describe the relationship between the P/C ratio of EPS and a number of biophysical properties related to biopolymer aggregation propensity, e.g., relative hydrophobicity, surface activity and surface tension, attachment efficiency, light-induced chemical crosslinking, and sedimentation efficiency of marine snow in marine environments.
Heavy metal in wastewater is a crucial concern due to its toxicological manifestations on human health, particularly in developing countries. Compared to different conventional heavy metal removal ...methods, cyanobacteria mediated heavy metal removal is a potential method, as it is a cost-effective, in situ operable, and green chemistry approach. They are excellent tools for multidirectional metal sequestration operations as they can simultaneously sequester metal through biosorption and bioaccumulation. Biosorption is a cell surface phenomenon, whereas bioaccumulation occurs inside the cell. This study reviewed deeply how cyanobacteria sequester heavy metal ions by these two processes from an ambient water body and the defense mechanism of cyanobacteria against metal-induced toxicity. Further, among the different components of the cyanobacteria's cell wall, this blue-green algae biosorb the metal ion mainly through Exopolysaccharide (EPS). The article discusses several pathways of EPS biosynthesis to know the potential engineering approach for producing this incredible polymer, which facilitates its metal ion adsorption property. Furthermore, we compare different cyanobacterial species' ability to sequester heavy metals from water in different environmental conditions. Limnococcussp, Nostocmuscorum, and Synechococcus sp. PCC 7942 shows optimum efficiency based on heavy metal removal, multi-metal removal by biosorption and bioaccumulation, and contact time. Finally we for the first time, discussed the circadian clock application in the cyanobacterial metal ion sequestration process, which might disclose the molecular-level mechanisms of cyanobacteria to sequester metal ions and different defense mechanisms.
Biofilm formation is initiated by adhesion of individual bacteria to a surface. However, surface adhesion alone is not sufficient to form the complex community architecture of a biofilm. ...Surface-sensing creates bacterial awareness of their adhering state on the surface and is essential to initiate the phenotypic and genotypic changes that characterize the transition from initial bacterial adhesion to a biofilm. Physico-chemistry has been frequently applied to explain initial bacterial adhesion phenomena, including bacterial mass transport, role of substratum surface properties in initial adhesion and the transition from reversible to irreversible adhesion. However, also emergent biofilm properties, such as production of extracellular-polymeric-substances (EPS), can be surface-programmed. This review presents a four-step, comprehensive description of the role of physico-chemistry from initial bacterial adhesion to surface-programmed biofilm growth: (1) bacterial mass transport towards a surface, (2) reversible bacterial adhesion and (3) transition to irreversible adhesion and (4) cell wall deformation and associated emergent properties. Bacterial transport mostly occurs from sedimentation or convective-diffusion, while initial bacterial adhesion can be described by surface thermodynamic and Derjaguin−Landau−Verwey−Overbeek (DLVO)-analyses, considering bacteria as smooth, inert colloidal particles. DLVO-analyses however, require precise indication of the bacterial cell surface, which is impossible due to the presence of bacterial surface tethers, creating a multi-scale roughness that impedes proper definition of the interaction distance in DLVO-analyses. Application of surface thermodynamics is also difficult, because initial bacterial adhesion is only an equilibrium phenomenon for a short period of time, when bacteria are attached to a substratum surface through few surface tethers. Physico-chemical bond-strengthening occurs in several minutes leading to irreversible adhesion due to progressive removal of interfacial water, conformational changes in cell surface proteins, re-orientation of bacteria on a surface and the progressive involvement of more tethers in adhesion. After initial bond-strengthening, adhesion forces arising from a substratum surface cause nanoscopic deformation of the bacterial cell wall against the elasticity of the rigid peptidoglycan layer positioned in the cell wall and the intracellular pressure of the cytoplasm. Cell wall deformation not only increases the contact area with a substratum surface, presenting another physico-chemical bond-strengthening mechanism, but is also accompanied by membrane surface tension changes. Membrane-located sensor molecules subsequently react to control emergent phenotypic and genotypic properties in biofilms, most notably adhesion-associated ones like EPS production. Moreover, also bacterial efflux pump systems may be activated or mechano-sensitive channels may be opened upon adhesion-induced cell wall deformation. The physico-chemical properties of the substratum surface thus control the response of initially adhering bacteria and through excretion of autoinducer molecules extend the awareness of their adhering state to other biofilm inhabitants who subsequently respond with similar emergent properties. Herewith, physico-chemistry is not only involved in initial bacterial adhesion to surfaces but also in what we here propose to call “surface-programmed” biofilm growth. This conclusion is pivotal for the development of new strategies to control biofilm formation on substratum surfaces, that have hitherto been largely confined to the initial bacterial adhesion phenomena.
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•Physico-chemistry dictates initial bacterial adhesion to substratum surfaces•Bond-strengthening leads to irreversible adhesion of bacteria (and inert colloids)•Through quorum-sensing, bacteria share information on substratum surface properties•Substratum surface properties program emergent biofilm properties•Regarding bacteria as inert colloids, does not yield a generalized biofilm model
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