Synergistic binding mechanisms of co-contaminants in soil profiles: Influence of iron-bearing minerals and microbial communities.

In contaminated soil sites, the coexistence of inorganic and organic contaminants poses a significant threat to both the surrounding ecosystem and public health. However, the migration characteristics of these co-contaminants within the soil and their interactions with key components, including Fe-bearing minerals, organic matter, and microorganisms, remain unclear. This study involved the collection of a 4.3-m-depth co-contaminated soil profile to investigate the vertical distribution patterns of co-contaminants (namely, arsenic, cadmium, and polychlorinated biphenyls (PCBs)) and their binding mechanisms with environmental factors. The results indicated a notable downward accumulation of inorganic contaminants with increasing soil depth, whereas PCBs were predominantly concentrated in the uppermost layer. Chemical extraction and synchrotron radiation analysis highlighted a positive correlation between the abundance of reactive iron (FeCBD) and both co-contaminants and microbial communities in the contaminated site. Furthermore, Mantel tests and structural equation modeling (SEM) demonstrated the direct impacts of FeCBD and microbial communities on co-contaminants within the soil profile. Overall, these results provided valuable insights into the migration and transformation characteristics of co-contaminants and their binding mechanisms mediated by minerals, organic matter, and microorganisms.

Health-related quality of life in Chinese SLE patients: evidence from 1568 SLE patients and 2610 healthy controls.

OBJECTIVE: To investigate the effects of systemic lupus erythematosus (SLE) on health-related quality of life (HRQOL), the relationship between disease activity and HRQOL, and potential factors affecting HRQOL in Chinese SLE patients. METHODS: This study recruited 1568 patients and 2610 controls to explore the effects of SLE on HRQOL. The association between disease activity and HRQOL, and the influencing factors of HRQOL were determined in 1568 patients. Then, we prospectively followed 1096 patients to explore the association between reduced disease activity and improved HRQOL, and the influencing factors of improved HRQOL. The Short-Form 36 (SF-36) and SLE disease activity index (SLEDAI) were used to evaluate HRQOL and disease activity. RESULTS: Chinese SLE patients had lower HRQOL than controls in all domains (P < 0.001), especially in role-physical (RP) and role-emotional (RE). Compared with SLE patients from outside China, the HRQOL of Chinese patients appeared to be higher in mental component summary (MCS) but lower in RP and RE. SLEDAI was negatively correlated with HRQOL, which was validated using the results of a follow-up study, where SLEDAI reduction was positively associated with HRQOL improvements (P < 0.05). Furthermore, personality, life nervous and experiences of adverse life events may influence HRQOL and HRQOL improvements. CONCLUSION: SLE significantly affected the HRQOL of Chinese patients, especially in RP and RE. Disease activity was negatively correlated with HRQOL. We also found for the first time some factors affecting HRQOL, which can be regarded as the basis for improving the HRQOL of SLE patients.

Increased regional Hurst exponent reflects response inhibition related neural complexity alterations in pediatric bipolar disorder patients during an emotional Go-Nogo task.

Fractal patterns have been shown to change in resting- and task-state blood oxygen level-dependent signals in bipolar disorder patients. However, fractal characteristics of brain blood oxygen level-dependent signals when responding to external emotional stimuli in pediatric bipolar disorder remain unclear. Blood oxygen level-dependent signals of 20 PBD-I patients and 17 age- and sex-matched healthy controls were extracted while performing an emotional Go-Nogo task. Neural responses relevant to the task and Hurst exponent of the blood oxygen level-dependent signals were assessed. Correlations between clinical indices and Hurst exponent were estimated. Significantly increased activations were found in regions covering the frontal lobe, parietal lobe, temporal lobe, insula, and subcortical nuclei in PBD-I patients compared to healthy controls in contrast of emotional versus neutral distractors. PBD-I patients exhibited higher Hurst exponent in regions that involved in action control, such as superior frontal gyrus, inferior frontal gyrus, inferior temporal gyrus, and insula, with Hurst exponent of frontal orbital gyrus correlated with onset age. The present study exhibited overactivation, increased self-similarity and decreased complexity in cortical regions during emotional Go-Nogo task in patients relative to healthy controls, which provides evidence of an altered emotional modulation of cognitive control in pediatric bipolar disorder patients. Hurst exponent may be a fractal biomarker of neural activity in pediatric bipolar disorder.

Integrated Multi-Omics Analyses Reveal That Autophagy-Mediated Cellular Metabolism Is Required for the Initiation of Pollen Germination.

Autophagy is an evolutionarily conserved mechanism for degrading and recycling various cellular components, functioning in both normal development and stress conditions. This process is tightly regulated by a set of autophagy-related (ATG) proteins, including ATG2 in the ATG9 cycling system and ATG5 in the ATG12 conjugation system. Our recent research demonstrated that autophagy-mediated compartmental cytoplasmic deletion is essential for pollen germination. However, the precise mechanisms through which autophagy regulates pollen germination, ensuring its fertility, remain largely unknown. Here, we applied multi-omics analyses, including transcriptomic and metabolomic approaches, to investigate the downstream pathways of autophagy in the process of pollen germination. Although ATG2 and ATG5 play similar roles in regulating pollen germination, high-throughput transcriptomic analysis reveals that silencing ATG5 has a greater impact on the transcriptome than silencing ATG2. Cross-comparisons of transcriptome and proteome analysis reveal that gene expression at the mRNA level and protein level is differentially affected by autophagy. Furthermore, high-throughput metabolomics analysis demonstrates that pathways related to amino acid metabolism and aminoacyl-tRNA biosynthesis were affected by both ATG2 and ATG5 silencing. Collectively, our multi-omics analyses reveal the central role of autophagy in cellular metabolism, which is critical for initiating pollen germination and ensuring pollen fertility.

Mycorrhizae enhance reactive minerals but reduce mineral-associated carbon.

Soil organic carbon (C) is the largest active C pool of Earth's surface and is thus vital in sustaining terrestrial productivity and climate stability. Arbuscular mycorrhizal fungi (AMF) form symbioses with most terrestrial plants and critically modulate soil C dynamics. Yet, it remains unclear whether and how AMF-root associations (i.e., mycorrhizae) interact with soil minerals to affect soil C cycling. Here we showed that the presence of both roots and AMF increased soil dissolved organic C and reactive Fe minerals, as well as litter decomposition and soil CO2 emissions. However, it reduced mineral-associated C. Also, high-resolution nanoscale secondary ion mass spectrometry images showed the existence of a thin coating (0.5-1.0 µm thick) of 56 Fe16 O- (Fe minerals) on the surface of 12 C14 N- (fungal biomass), illustrating the close physical association between fungal hyphae and soil Fe minerals. In addition, AMF genera were divergently related to reactive Fe minerals, with Glomus being positively but Paraglomus and Acaulospora negatively correlated with reactive Fe minerals. Moreover, the presence of roots and AMF, particularly when combined with litter addition, enhanced the abundances of several critical soil bacterial genera that are associated with the formation of reactive minerals in soils. A conceptual framework was further proposed to illustrate how AMF-root associations impact soil C cycling in the rhizosphere. Briefly, root exudates and the inoculated AMF not only stimulated the decomposition of litter and SOC and promoted the production of CO2 emission, but also drove soil C persistence by unlocking mineral elements and promoting the formation of reactive minerals. Together, these findings provide new insights into the mechanisms that underlie the formation of reactive minerals and have significant implications for understanding and managing soil C persistence.

Organic carbon preservation in wetlands: Iron oxide protection vs. thermodynamic limitation.

The sequestration of organic carbon (OC) in wetland sediments is influenced by the presence of oxygen or lack thereof. The mechanisms of OC sequestration under redox fluctuations, particularly by the co-mediation of reactive iron (Fe) protection and thermodynamic limitation by the energetics of the OC itself, remain unclear. Over the past 26 years, a combination of field surveys and remote sensing images had revealed a strong decline in both natural and constructed wetland areas in Tianjin. This decline could be attributed to anthropogenic landfill practices and agricultural reclamation efforts, which may have significant impacts on the oxidation-reduction conditions for sedimentary OC. The Fe-bound OC (CBD extraction) decreased by 2 to 10-fold (from 8.3 to 10% to 0.7-4.5%) with increasing sediment depth at three sites with varying water depths (WD). The high-resolution spectro-microscopy analysis demonstrated that Fe (oxyhydr)oxides were colocalized with sedimentary OC. Corresponding to lower redox potential, the nominal oxidation state of C (NOSC), which corresponds to the energy content in OC, became more negative (energy content increased) with increasing sediment depth. Taken together, the preservation of sedimentary OC is contingent on the prevailing redox conditions: In environments where oxygen availability is high, reactive Fe provides protection for OC, while in anoxic environments, thermodynamic constraints (i.e., energetic constraints) limit the oxidation of OC.

[Spatiotemporal Characteristics and Influencing Factors of Environment Emergency Incident in China from 1991 to 2018].

Research on the spatiotemporal characteristics and influencing factors of environmental emergency incidents in China in recent decades can improve the effectiveness and accuracy of risk supervision of environmental emergency incidents. Based on the data of environmental emergency incidents in 31 provincial regions in China from 1991 to 2018, this study used spatial autocorrelation analysis and a geographically and temporally weighted regression model to analyze the spatial dependence of environmental emergency incidents and the temporal and spatial heterogeneity of influencing factors. The results showed that: ① there was a significant positive spatial correlation between environmental emergency incidents during 1991-1994 and 2001-2014, and the spatial agglomeration was gradually increasing, that is, environmental emergency incidents existed in the provinces of China; clearly, the space depended on the characteristics and was not completely random. ② There was an unbalanced development pattern of environmental emergency incidents in China. The provinces with "L-L" agglomeration were concentrated in the western and northeastern regions, and the number increased and then decreased; by contrast, the ones with "H-H" agglomeration shifted from the east and south to the central and western regions, and the number increased following the decrease. The role of environmental emergency incident in different provincial regions in the spatial agglomeration was different and constantly changing. ③ The effects of various influencing factors on environmental emergency incidentshad obvious temporal and spatial heterogeneity in different periods and different provinces. The impact of the level of economic development on environmental emergency incidents was shown as a "negative-positive-negative" pattern. The impact of industrial structure on environmental emergency incidents was shown as a "negative-positive" pattern. The overall impact of pollution emissions on environmental emergency incident presented a "positive-negative-positive" pattern. Environmental letters and visits had a positive impact on the occurrence of environmental emergency incidents. The negative impact of the legal environment on environmental emergency incidents was gradually weakening. The negative impact of pollution control on environmental emergency incidents at the provincial level has gradually become apparent.

Multiple Effects of Humic Components on Microbially Mediated Iron Redox Processes and Production of Hydroxyl Radicals.

Microbially mediated iron redox processes are of great significance in the biogeochemical cycles of elements, which are often coupled with soil organic matter (SOM) in the environment. Although the influences of SOM fractions on individual reduction or oxidation processes have been studied extensively, a comprehensive understanding is still lacking. Here, using ferrihydrite, Shewanella oneidensis MR-1, and operationally defined SOM components including fulvic acid (FA), humic acid (HA), and humin (HM) extracted from black soil and peat, we explored the SOM-mediated microbial iron reduction and hydroxyl radical (•OH) production processes. The results showed that the addition of SOM inhibited the transformation of ferrihydrite to highly crystalline iron oxides. Although FA and HA increased Fe(II) production over four times on average due to complexation and their high electron exchange capacities, HA inhibited 30-43% of the •OH yield, while FA had no significant influence on it. Superoxide (O2•-) was the predominant intermediate in •OH production in the FA-containing system, while one- and two-electron transfer processes were concurrent in HA- and HM-containing systems. These findings provide deep insights into the multiple mechanisms of SOM in regulating microbially mediated iron redox processes and •OH production.

Associations of RPEL1 and miR-1307 gene polymorphisms with disease susceptibility, glucocorticoid efficacy, anxiety, depression, and health-related quality of life in Chinese systemic lupus erythematosus patients.

OBJECTIVE: Our present study intended to examine the associations of RPEL1 and miR-1307 gene polymorphisms (rs4917385 and rs7911488) with susceptibility, glucocorticoids (GCs) efficacy, anxiety, depression, and health-related quality of life (HRQoL) in Chinese systemic lupus erythematosus (SLE) patients. METHODS: Initially, 1000 participants (500 SLE cases and 500 controls) were recruited for the case-control study. Then, 429 cases who received GCs were followed through 12 weeks to explore GCs efficacy, depression, anxiety, and HRQoL. We selected the iMLDR technique for genotyping: RPEL1: rs4917385 (G/T) and miR-1307: rs7911488 (A/G). RESULTS: The minor G allele of rs7911488 reduced the risk of SLE (p = .024). Four haplotypes consisting of rs4917385 and rs7911488 were associated with SLE susceptibility (p < .025). Both rs4917385 and rs7911488 were associated with anxiety symptoms and physical function (PF) in SLE patients (p < .025). The rs4917385 was associated with depression and its improvement. No statistical significance was found between RPEL1 and miR-1307 gene polymorphisms with GCs efficacy. Meanwhile, additive interaction analysis showed a significant association between RPEL1 and miR-1307 gene polymorphisms with tea consumption in anxiety. CONCLUSION: RPEL1 and miR-1307 gene polymorphisms (rs4917385 and rs7911488) might be related to SLE susceptibility in Chinese population. Additionally, the two polymorphisms were possibly associated with depression, anxiety, and HRQoL in Chinese SLE population.

An association study on the risk, glucocorticoids effectiveness, and prognosis of systemic lupus erythematosus: insight from mitochondrial DNA copy number.

This study aimed to explore the role of mitochondrial DNA copy number (mtDNAcn) in the risk, glucocorticoid (GC) effectiveness, and prognosis of systemic lupus erythematosus (SLE) and its interactions with environmental factors and tumor necrosis factor receptor-associated protein 1 (TRAP1) genetic polymorphisms. We first conducted a case-control study of 1198 subjects (595 SLE patients and 603 healthy controls). Subsequently, we followed up with patients to assess the effectiveness of GC treatment and the prognosis of SLE. Real-time fluorescent quantitative PCR (qPCR) was used to quantify mtDNAcn. Associations were estimated using logistic regression, and prognosis analysis was performed using Kaplan-Meier analysis and Cox proportional hazards models. Interactions on multiplicative and additive scales were also evaluated. Individuals with low mtDNAcn had an increased risk of SLE (P < 0.001). Low mtDNAcn was associated with poor GC effectiveness in patients with spicy food consumption or with arthritis (P < 0.05). mtDNAcn was significantly related to the prognosis of SLE in the drinking subgroup (P = 0.018). Furthermore, we found significant interactions between mtDNAcn and environmental factors/TRAP1 genetic polymorphisms on the risk, GC effectiveness, and prognosis of SLE. Our data suggest that low mtDNAcn is associated with an increased risk of SLE. Alteration of mtDNAcn may be associated with GC effectiveness and prognosis in certain subgroups of SLE. The interactions between mtDNAcn, environmental factors, and TRAP1 gene polymorphisms may jointly affect the risk, GC effectiveness, and prognosis of SLE.

Microbial community mediates hydroxyl radical production in soil slurries by iron redox transformation.

The generation of reactive oxygen species (ROS) mediated by minerals and/or microorganisms plays a vital but underappreciated role in affecting carbon and nutrient cycles at soil-water interfaces. It is currently unknown which interactions between microbial communities and iron (Fe) minerals produce hydroxyl radical (HO•), which is the strongest oxidant among ROS. Using a series of well-controlled anoxic incubations of soil slurries, we demonstrated that interactions between microbial communities and Fe minerals synergistically drove HO• production (up to ∼100 nM after 21-day incubation). Microorganisms drove HO• generation in anoxic environments predominantly by modulating iron redox transformation that was more prominent than direct production of ROS by microorganisms. Among the microbial communities, Geobacter, Paucimonas, Rhodocyclaceae_K82, and Desulfotomaculum were the key genera strongly affecting HO• production. In manured soils, the former two species had higher abundances and were crucial for HO• production. In contrast, the latter two species were mainly abundant and important in soils with mineral fertilizers. Our study suggests that abundant highly reactive oxidant HO• can be generated in anoxic environments and the microbial community-mediated redox transformations of iron (oxyhydr)oxides may be responsible for the HO• production. These findings shed light on the microbial generation of HO• in fluctuating redox environments and on consequences for global C and nutrient cycling.

Molecular Trade-Offs between Lattice Oxygen and Oxygen Vacancy Drive Organic Pollutant Degradation in Fungal Biomineralized Exoskeletons.

Fungal-mineral interactions can effectively alleviate cellular stress from organic pollutants, the production of which are expected to rapidly increase owing to the Earth moving into an unprecedented geological epoch, the Anthropocene. The underlying mechanisms that may enable fungi to combat organic pollution during fungal-mineral interactions remain unclear. Inspired by the natural fungal sporulation process, we demonstrate for the first time that fungal biomineralization triggers the formation of an ultrathin (hundreds of nanometers thick) exoskeleton, enriched in nanosized iron (oxyhydr)oxides and biomolecules, on the hyphae. Mapped biochemical composition of this coating at a subcellular scale via high spatial resolution (down to 50 nm) synchrotron radiation-based techniques confirmed aromatic C, C-N bonds, amide carbonyl, and iron (oxyhydr)oxides as the major components of the coatings. This nanobiohybrid system appeared to impart a strong (×2) biofunctionality for fungal degradation of bisphenol A through altering molecular-level trade-offs between lattice oxygen and oxygen vacancy. Together, fungal coatings could act as "artificial spores", which enable fungi to combat physical and chemical stresses in natural environments, providing crucial insights into fungal biomineralization and coevolution of the Earth's lithosphere and biosphere.

Mixed-Linker Strategy for the Construction of Metal-Organic Framework Combined with Dyes toward Alcohol Detection.

Herein, a N-rich metal-organic framework (MOF) with four kinds of cages, Zn4(ade)2(TCA)2(H2O) (NENU-1000, Hade = adenine, H3TCA = 4,4',4″-tricarboxytriphenylamine, NENU = Northeast Normal University), was prepared by the mixed-ligand strategy. Cationic dyes can be selectively absorbed by NENU-1000 at proper concentrations, but not neutral and anionic dyes, which perhaps can be assigned to the N-rich neutral framework of NENU-1000. When NENU-1000 was introduced to a relatively lower concentration of cationic dye solutions (e.g., rhodamine B or basic red 2), the colors of these systems faded quickly. Furthermore, the faded solutions can be used for the detection of methanol and other small alcohol molecules with either the naked eye or common UV-vis spectra. The effect of the length of carbon chain, the position of the -OH group, and the number of the hydroxyl group of the alcohols was explored for the color development rate. In addition, the performance of NENU-1000 in iodine sorption and release was also studied.

Fungal-Mineral Interactions Modulating Intrinsic Peroxidase-like Activity of Iron Nanoparticles: Implications for the Biogeochemical Cycles of Nutrient Elements and Attenuation of Contaminants.

Fungal-mediated extracellular reactive oxygen species (ROS) are essential for biogeochemical cycles of carbon, nitrogen, and contaminants in terrestrial environments. These ROS levels may be modulated by iron nanoparticles that possess intrinsic peroxidase (POD)-like activity (nanozymes). However, it remains largely undescribed how fungi modulate the POD-like activity of the iron nanoparticles with various crystallinities and crystal facets. Using well-controlled fungal-mineral cultivation experiments, here, we showed that fungi possessed a robust defect engineering strategy to modulate the POD-like activity of the attached iron minerals by decreasing the catalytic activity of poorly ordered ferrihydrite but enhancing that of well-crystallized hematite. The dynamics of POD-like activity were found to reside in molecular trade-offs between lattice oxygen and oxygen vacancies in the iron nanoparticles, which may be located in a cytoprotective fungal exoskeleton. Together, our findings unveil coupled POD-like activity and oxygen redox dynamics during fungal-mineral interactions, which increase the understanding of the catalytic mechanisms of POD-like nanozymes and microbial-mediated biogeochemical cycles of nutrient elements as well as the attenuation of contaminants in terrestrial environments.

Root exudate chemistry affects soil carbon mobilization via microbial community reassembly.

Plant roots are one of the major mediators that allocate carbon captured from the atmosphere to soils as rhizodeposits, including root exudates. Although rhizodeposition regulates both microbial activity and the biogeochemical cycling of nutrients, the effects of particular exudate species on soil carbon fluxes and key rhizosphere microorganisms remain unclear. By combining high-throughput sequencing, q-PCR, and NanoSIMS analyses, we characterized the bacterial community structure, quantified total bacteria depending on root exudate chemistry, and analyzed the consequences on the mobility of mineral-protected carbon. Using well-controlled incubation experiments, we showed that the three most abundant groups of root exudates (amino acids, carboxylic acids, and sugars) have contrasting effects on the release of dissolved organic carbon (DOC) and bioavailable Fe in an Ultisol through the disruption of organo-mineral associations and the alteration of bacterial communities, thus priming organic matter decomposition in the rhizosphere. High resolution (down to 50 nm) NanoSIMS images of mineral particles indicated that iron and silicon co-localized significantly more organic carbon following amino acid inputs than treatments without exudates or with carboxylic acids. The application of sugar strongly reduced microbial diversity without impacting soil carbon mobilization. Carboxylic acids increased the prevalence of Actinobacteria and facilitated carbon mobilization, whereas amino acid addition increased the abundances of Proteobacteria that prevented DOC release. In summary, root exudate functions are defined by their chemical composition that regulates bacterial community composition and, consequently, the biogeochemical cycling of carbon in the rhizosphere.

Molybdenum Bioavailability and Asymbiotic Nitrogen Fixation in Soils are Raised by Iron (Oxyhydr)oxide-Mediated Free Radical Production.

Nitrogen (N) fixation in soils is closely linked to microbially mediated molybdenum (Mo) cycling. Therefore, elucidating the mechanisms and factors that affect Mo bioavailability is crucial for understanding N fixation. Here, we demonstrate that long-term (26 years) manure fertilization increased microbial diversity and content of short-range ordered iron (oxyhydr)oxides that raised Mo bioavailability (by 2.8 times) and storage (by ∼30%) and increased the abundance of nifH genes (by ∼14%) and nitrogenase activity (by ∼60%). Nanosized iron (oxyhydr)oxides (ferrihydrite, goethite, and hematite nanoparticles) play a dual role in soil Mo cycling: (i) in concert with microorganisms, they raise Mo bioavailability by catalyzing hydroxyl radical (HO•) production via the Fenton reactions and (ii) they increase Mo retention by association with the nanosized iron (oxyhydr)oxides. In summary, long-term manure fertilization raised the stock and bioavailability of Mo (and probably also of other micronutrients) by increasing iron (oxyhydr)oxide reactivity and intensified asymbiotic N fixation through an increased abundance of nifH genes and nitrogenase activity. This work provides a strategy for increasing biological N fixation in agricultural ecosystems.

Coupling thermophilic composting and vermicomposting processes to remove Cr from biogas residues and produce high value-added biofertilizers.

Removing pollutants and producing high value-added products are essential steps for sustainable disposal and utilization of biogas residues. Here, a coupled thermophilic composting and vermicomposting process was used to remove Cr from biogas residues, and the composting products were co-fermented with the plant growth-promoting fungus Trichoderma to produce high value-added biofertilizers. The results showed that thermophilic composting for 37 d markedly increased the total content of Cr but decreased the percentage of available Cr fractions. Synchrotron-radiation-based observations further provided direct evidence of the binding sites to support the results from traditional sequential extraction. At a density of 60 g earthworm/kg biogas residues, vermicomposting removed 23-31% of Cr from biogas residues. After vermicomposting, co-fermentation of biogas residues and Trichoderma was optimized, in which Trichoderma spores were 2-5 × 108 cfu/g substrates. Together, coupling thermophilic composting and vermicomposting processes is a promising technique to remove a portion of heavy metals from biogas residues.

Intrinsic enzyme-like activity of magnetite particles is enhanced by cultivation with Trichoderma guizhouense.

Fungal-mineral interactions can produce large amounts of biogenic nano-size (~ 1-100 nm) minerals, yet their influence on fungal physiology and growth remains largely unexplored. Using Trichoderma guizhouense NJAU4742 and magnetite (Mt) as a model fungus and mineral system, we have shown for the first time that biogenic Mt nanoparticles formed during fungal-mineral cultivation exhibit intrinsic peroxidase-like activity. Specifically, the average peroxidase-like activity of Mt nanoparticles after 72 h cultivation was ~ 2.4 times higher than that of the original Mt. Evidence from high resolution X-ray photoelectron spectroscopy analyses indicated that the unique properties of magnetite nanoparticles largely stemmed from their high proportion of surface non-lattice oxygen, through occupying surface oxygen-vacant sites, rather than Fe redox chemistry, which challenges conventional Fenton reaction theories that assume iron to be the sole redox-active centre. Nanoscale secondary ion mass spectrometry with a resolution down to 50 nm demonstrated that a thin (< 1 µm) oxygen-film was present on the surface of fungal hyphae. Furthermore, synchrotron radiation-based micro-FTIR spectra revealed that surface oxygen groups corresponded mainly to organic OH, mineral OH and carbonyl groups. Together, these findings highlight an important, but unrecognized, catalytic activity of mineral nanoparticles produced by fungal-mineral interactions and contribute substantially to our understanding of mineral nanoparticles in natural ecosystems.

Mechanisms of potentially toxic metal removal from biogas residues via vermicomposting revealed by synchrotron radiation-based spectromicroscopies.

Biogas residues (BR) contaminated with potentially toxic metals pose environmental risks to soils and food chains, and strategies are needed to decrease the concentration and bioavailability of potentially toxic metals in BR. Here, metal fractions and removal mechanisms were quantified by synchrotron radiation-based Fourier transform infrared and micro X-ray fluorescence spectromicroscopies on BR and earthworms subject to vermicomposting. Vermicomposting resulted in decreases in concentrations of potentially toxic metals in BR and increases in metal removal efficiencies due to uptake by earthworms. Prior to vermicomposting, Zn, Cu and Pb were associated with N-H, O-H, aromatic C, aliphatic C, and amide functional groups, but following maturation during vermicomposting, metals were associated with N-H, O-H, aliphatic C and polysaccharide functional groups. Following vermicomposting, Zn and Cu were mainly distributed in the dermal portions of earthworms, whereas Pb was more homogeneously distributed among the inner and outer portions of the earthworms, revealing that different metals may have different uptake routes. These findings provide a new strategy for safe utilization of BR by using earthworms via vermicomposting to remove potentially toxic metals and in situ insights into how metals binding and distribution characteristics in BR and earthworms during compost and vermicomposting processes.

Biological removal of cadmium from biogas residues during vermicomposting, and the effect of earthworm hydrolysates on Trichoderma guizhouense sporulation.

The removal efficiency of Cd from biogas residues (BR) by earthworms (Eisenia fetida) during vermicomposting and the optimum addition of earthworm hydrolysates for production of Trichoderma guizhouense NJAU 4742 spores were determined. The results showed that vermicomposting could effectively remove Cd (up to 18.9%) from the BR. Synchrotron radiation based FTIR spectromicroscopy demonstrated a weakened correlation between functional groups after vermicomposting, suggesting that the activity of earthworms affects the binding sites and bioavailability of heavy metals. Under optimum conditions, the hydrolysis rate of earthworms was ~97% and the removal efficiency of Cd was up to 93%. Furthermore, addition of 20% of earthworm hydrolysate promoted the largest production of Trichoderma sporulation (~2.95 × 108 cfu/g straw), indicating the possibility of earthworm hydrolysates promoting the growth of Trichoderma guizhouense is a suitable way to recycle earthworms after vermicomposting.