The state of the art of the reported data on interactions between microorganisms and HSs is presented herein. The properties of HSs are discussed in terms of microbial utilization, degradation, and ...transformation. The data on biologically active individual compounds found in HSs are summarized. Bacteria of the phylum Proteobacteria and fungi of the phyla Basidiomycota and Ascomycota were found to be the main HS degraders, while Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes were found to be the predominant phyla in humic-reducing microorganisms (HRMs). Some promising aspects of interactions between microorganisms and HSs are discussed as a feasible basis for nature-like biotechnologies, including the production of enzymes capable of catalyzing the oxidative binding of organic pollutants to HSs, while electron shuttling through the utilization of HSs by HRMs as electron shuttles may be used for the enhancement of organic pollutant biodegradation or lowering bioavailability of some metals. Utilization of HSs by HRMs as terminal electron acceptors may suppress electron transfer to CO2, reducing the formation of CH4 in temporarily anoxic systems. The data reported so far are mostly related to the use of HSs as redox compounds. HSs are capable of altering the composition of the microbial community, and there are environmental conditions that determine the efficiency of HSs. To facilitate the development of HS-based technologies, complex studies addressing these factors are in demand.
Nature-like technologies can be considered as a logical development of green chemistry principles implemented to design novel materials and processes aimed at mimicking and reproducing natural ...life-sustaining mechanisms on molecular level. Humic substances which penetrate throughout the entire environment and represent from 50 to 90% of organic matter in soil and water ecosystems, play multiple life-sustaining functions on Earth. To name a few, HS regulate transport and availability of biogenic elements to plants, immobilize and mitigate toxicity of hazardous elements in the contaminated ecosystems, protect plants from non-specific abiotic stresses, play key role for fertility of soils determining water-retention and structure. Here we represent a novel platform for nature-inspired synthesis of soft and hybrid (nano)materials aimed at their use for soil and water clean up, carbon sequestration, soil fertility restoration. It is based on a smart use of natural hyperbranched polyelectrolytes – humic substances, which possess multiple functional groups including carboxyl, hydroxyl, amide, and others. Multiple functional groups of HS make them amenable both for classical chemical modification as well as for producing interpolyelectrolyte complexes. In this work, we present both approaches for manufacturing silicon-containing humic derivatives and supramolecular complexes with acquired new property – self-adhesion to both inorganic and bio-surfaces. The synthesis is conducted using humic materials from different sources and functional organosilanes. Self-assembly of the supramolecular silicon-humic systems occurs with formation of humic-silsesquioxane networks capable to adhere to mineral surfaces. This process is similar to immobilization of organic coatings to mineral surfaces. We have shown how this process can be realized in the ground waters for the purposes of the environmental clean up. We have also proposed to use the silicon-humic complexes for improving humus content of soils and for reconstructing soil restoration processes both in the lab and in the field. Another field of our research is synthesis of iron-containing humics-stabilized nanoparticles (NPs), which can be used as a source for plants nutrition instead of synthetic iron chelates. The idea is based on the natural phenomenon that in soils, water-stable sols of iron-containing NPs are formed due to complexing with HS, which can bind large amounts of poorly ordered iron (hydr)oxides providing for stabilization of colloidal iron in the form of NPs. It has been numerously shown that the presence of HS improves iron acquisition by plants in soils, but there was no systematic study so far with respect to a relationship between size and crystallinity of humics-stabilized iron-containing NPs and their availability to plants. We have conducted such a study and could establish conditions when humics-stabilized NPs could be taken up by plants with similar efficiency as FeEDTA. The presented data demonstrate good prospects for a use of green humics-based materials in nature-like technologies. We also hope that these studies will give rise to new branch of chemistry and technology which can be called ecoadaptive chemistry and technology.
The present study introduces NOMspectra, a Python package for processing high resolution mass spectrometry data on complex systems of natural organic matter (NOM). NOM is characterized by ...multicomponent composition reflected as thousands of signals producing very complex patterns in high resolution mass spectra. This complexity sets special demands on the methods of data processing used for analysis. The developed NOMspectra package offers a comprehensive workflow for processing, analyzing, and visualizing information-rich mass spectra of NOM and HS including algorithms for filtering spectra, recalibrating, and assigning elemental compositions to molecular ions. Additionally, the package includes functions for calculating various molecular descriptors and methods for data visualization. A graphical user interface (GUI) has been developed to make a user-friendly interface for the proposed package.
The occurrence and distribution of antibiotics in the environment has received increasing attention due to their potential adverse effects on human health and ecosystems. Humic substances (HS) ...influence the mobility, reactivity, and bioavailability of antibiotics in the environment significantly due to their interaction. As a result, HS can affect the dissemination of antibiotic-resistance genes, which is one of the main problems arising from contamination with antibiotics. The review provides quantitative data on the binding of HS with fluoroquinolones, macrolides, sulfonamides, and tetracyclines and reports the proposed mechanisms of their interaction. The main issues of the quantification of antibiotic-HS interaction are discussed, which are a development of standard approaches and the accumulation of a dataset using a standard methodology. This would allow the implementation of a meta-analysis of data to reveal the patterns of the binding of antibiotics to HS. Examples of successful development of humic-based sorbents for fluoroquinolone and tetracycline removal from environmental water systems or polluted wastewaters were given. Data on the various effects of HS on the dissemination of antibiotic-resistance genes (ARGs) were summarized. The detailed characterization of HS properties as a key point of assessing the environmental consequences of the formation of antibiotic-HS complexes, such as the dissemination of antibiotic resistance, was proposed.
Aquaculture has become imperative to cover the demands for dietary animal protein. Simultaneously, it has to overcome prejudices from excessive use of antibiotics and environmental impacts. Natural ...supplements are traditionally applied orally. In this study, we demonstrated another pathway: the gills. Humic substances are immunostimulants and a natural part of every aquatic ecosystem, making them ideal to be used as bath stimulants. Five and 50 mg C/L of a fulvic acid-rich humic substance was added for 28 days to the water of juvenile rainbow trout (Oncorhynchus mykiss). This fulvic acid is characterized by a high content of phenolic moieties with persistent free radicals and a high electron exchange capacity. The high concentration of the fulvic acid significantly increased growth and reduced the food conversion ratio and the response to a handling-stressor. Phagocytosis and potential killing activity of head kidney leukocytes were increased, as well as the total oxyradical scavenging capacity (TOSC) and lysozyme activity in the gills. In conclusion, immunostimulation via gills is possible with our fulvic acid, and the high phenolic content improved overall health and stress resistance of fish.
The goal of this study was to establish a relationship between the optical properties of soil dissolved organic matter (DOM) and acidic functions carried out by its individual constituents. We ...obtained 12 fractions of DOM samples using sequential solid phase extraction on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which correspond to low bounds of pK a values of phenols, aliphatic, and aromatic carboxylic acids, and ketoacids. The structural studies were conducted with the use of NMR and selective deuteromethylation of isolated fractions coupled to ultrahigh resolution mass spectrometry. First, a gradual shift of molecular compositions was observed from reduced components to aromatic oxidized compounds isolated at pH 7 and 2, respectively. Changes in molecular compositions were accompanied by a red shift of fluorescence spectra. Further application of deuteromethylation enabled us to distinguish DOM constituents with different amounts of carboxylic groups. Moreover, identification of structural isomers in a single DOM sample was achieved. Statistical analysis revealed that red shift of fluorescence is facilitated by the increase of a contribution of aromatic poly(carboxylic acid)s with high conjugation lengths. Additionally, analysis of the labeled fractionated permafrost thaw DOM directly showed carboxyl-rich alicyclic molecules, while the same components from lower-latitude DOM were assigned to lignin-like species.
Direct comparison of high-resolution mass spectrometry (HRMS) data acquired with different instrumentation or parameters remains problematic as the derived lists of molecular species via HRMS, even ...for the same sample, appear distinct. This inconsistency is caused by inherent inaccuracies associated with instrumental limitations and sample conditions. Hence, experimental data may not reflect a corresponding sample. We propose a method that classifies HRMS data based on the differences in the number of elements between each pair of molecular formulae within the formulae list to preserve the essence of the given sample. The novel metric, formulae difference chains expected length (FDCEL), allowed for comparing and classifying samples measured by different instruments. We also demonstrate a web application and a prototype for a uniform database for HRMS data serving as a benchmark for future biogeochemical and environmental applications. FDCEL metric was successfully employed for both spectrum quality control and examination of samples of various nature.
Natural products, such as humic substances (HS) and shilajit, are known to possess antiviral activity. Humic-like components are often called as carriers of biological activity of shilajit. The goal ...of this study was to evaluate anti-HIV activity of well characterized HS isolated from coal, peat, and peloids, and compare it to that of water-soluble organic matter (OM) isolated from different samples of Shilajit. The set of humic materials included 16 samples of different fractional composition: humic acid (HA), hymatomelanic acid (HMA), fulvic acid (FA). The set of shilajit OM included 19 samples of different geographic origin and level of alteration. The HIV-1 p24 antigen assay and cell viability test were used for assessment of antiviral activity. The HIV-1 Bru strain was used to infect CEM-SS cells. The obtained EC50 values varied from 0.37 to 1.4 mg L−1 for the humic materials, and from 14 to 142 mg L−1 for the shilajit OM. Hence, all humic materials used in this study outcompeted largely the shilajit materials with respect to anti-HIV activity: For the humic materials, the structure-activity relationships revealed strong correlation between the EC50 values and the content of aromatic carbon indicating the most important role of aromatic structures. For shilajit OM, the reverse relationship was obtained indicating the different mechanism of shilajit activity. The FTICRMS molecular assignments were used for ChEMBL data mining in search of the active humic molecules. As potential carriers of antiviral activity were identified aromatic structures with alkyl substituents, terpenoids, N-containing analogs of typical flavonoids, and aza-podophyllotoxins. The conclusion was made that the typical humic materials and Shilajit differ greatly in molecular composition, and the humic materials have substantial preferences as a natural source of antiviral agents as compared to shilajit.
•Comparison of anti-HIV activity measured for the two large sets of humic materials and Shilajit water extracts demonstrated much higher activity of the humic materials.•Structure-activity relationships revealed leading role of aromatic structures in anti-HIV activity of humic substances, and the opposite trend was observed for shilajit.•13C NMR and FTICR MS studies revealed structural similarity of shilajit extract to fulvic acid.•Different mode of antiviral action is suggested for aromatics-rich humic materials (humic acids, hymatomelanic acids) and N-rich shilajit.
The present study proposes a novel application of humic substance-aminosilsesquioxane polyelectrolyte complexes (HS-ASQ) as dust suppressants. These complexes are synthesized through the reaction ...between humic substances (HS) and 3-aminopropyltriethoxysilane (APTES) in aqueous solution, resulting in the formation of active silanol groups that can bind to mineral surfaces and condense, forming gels. The HS-ASQ compositions were found to have a high sorption capacity for dust particles and could form coatings on their surface without cementing the dust, making them potentially useful for environmental applications. The viscosity of the HS-ASQ compositions can be controlled by adding carboxymethylcellulose (CMC), which also enhances their dust suppression abilities. Different compositions of HS-ASQ were synthesized by varying the proportions of APTES and CMC, and dust treated with these samples was assessed for its resistance to wind erosion using a laboratory-scale setup. Treatment with the HS-ASQ composition resulted in substantial reductions in PM10 and PM2.5 concentrations (particulate matter with aerodynamic diameters of 10 µm and 2.5 µm, respectively) of up to 77% and 85%, respectively, compared to the control.
Humic substances (HS) in the aqueous solutions can be considered as colloidal particles formed by amphiphilic units. HS form micelles-like structures at concentrations close to 5 g/L. However ...colloidal behavior of HS at concentrations below 100 mg/L is unknown. Using radiotracer assay we have shown that in this concentration range HS form rare adsorption layers at the liquid/liquid interface and penetrate into the organic phase with the distribution ratio close to 10−3. We found that pH and HS molecular weight strongly influence on the distribution ratio but do not significantly change the adsorption. Furthermore, colloidal properties of HS are strongly depending on its origin: the highest surface activity was shown for HS separated from peat and the least was observed for HS separated from soils. We anticipate our assay to be a helpful tool for detailed analysis and modeling HS and humic-like materials colloidal behavior in the environment.
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•Tritium labeled humic substances (HS) were used to scale its hydrophobicity.•Toluene-water distribution coefficient linearly correlates with octanol-water coefficient.•Tritium labeled HS were used to scale its adsorption at the liquid-liquid interface.•Adsorption isotherms of HS at the liquid-liquid interface is of Langmuir type.•Novel method of HS characterization is developed.
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