Humification process and mechanisms investigated by Fenton-like reaction and laccase functional expression during composting

Exploring the Influence of Biochar-Supported Nano-Iron Oxide on Phosphorus Speciation Transformation and Bacterial Community Structure in Aerobic Pig Manure Composting Processes

Existing studies have demonstrated the positive effects of nano-sized iron oxide on compost maturity, yet the impact of nano-sized iron oxide on phosphorus speciation and bacterial communities during the composting process remains unclear. In this study, pig manure and straw were used as raw materials, with biochar-supported nano-sized iron oxide (BC-Fe3O4NPs) as an additive and calcium peroxide (CaO2) as a co-agent, to conduct an aerobic composting experiment with pig manure. Four treatments were tested: CK (control), F1 (1% BC-Fe3O4NPs), F2 (5% BC-Fe3O4NPs), and F3 (5% BC-Fe3O4NPs + 5% CaO2). Key findings include the following. (1) BC-Fe3O4NPs increased compost temperatures, with F3 reaching 61℃; F1 showed optimal maturity (C/N ratio: 12.90). (2) BC-Fe3O4NPs promoted stable phosphorus forms; Residual-P proportions were higher in F1, F2, and F3 (25.81%, 51.16%, 51.68%) than CK (19.32%). (3) Bacterial phyla Firmicutes, Actinobacteria, and Proteobacteria dominated. BC-Fe3O4NPs altered community composition, especially on day 7. Firmicutes dominated CK, F1, and F3; Proteobacteria dominated F2. At the genus level, day 7 showed Corynebacterium (CK), Clostridum (F1, F3), and Caldibacillus (F2) as predominant. (4) Pearson correlation analysis revealed shifted correlations between phosphorus forms and bacterial phyla after BC-Fe3O4NPs addition. Firmicutes positively correlated with NaOH-OP in F1 during the thermophilic phase, facilitating phosphate release and adsorption by BC-Fe3O4NPs. The significance of correlations diminished with increasing additive concentration; in F3, all phyla positively correlated with various phosphorus forms.

Effect of thermophilic bacterial complex agents on synergistic humification of carbon and nitrogen during lignocellulose-rich kitchen waste composting

This work reported the effects of thermophilic bacterial agents on degrading persistent lignocellulose and reducing the loss of valuable nitrogen in kitchen waste (KW) composting. The results showed that thermophilic bacterial compound agents improved the high temperature period by 8 days, and increased the ligninase activity by 0.5-3 times during the composting process. The activity of cellulase increased up to 1 time in agent A (Geobacillus, Clostridium caenicola, Haloplasma) adding group by improving the microbial activity of lignocellulosic degradation metabolic pathways. Nitrogen storage increased to 70% in group added with agent B (Clostridium caenicola, Geobacillus, Clostridium sp. TG60-81) by increasing the population abundance of nitrogen-fixing microorganisms such as Bacillus, Hungateiclostridium and Herbaspirillum, and changed amino acid metabolic pathways. In general, agents A and B could increase the thermophilic phase, optimize the microbial community structure, realize the synergistic humification of carbon and nitrogen, and convert KW into mature and high quality fertilizers.

Preference and regulation mechanism mediated via mobile genetic elements for antibiotic and metal resistomes during composting amended with nano ZVI loaded on biochar

This study assessed the effectiveness of nano zero-valent iron loaded on biochar (BC-nZVI) during swine manure composting. BC-nZVI significantly reduced the abundance of antibiotic resistance genes (ARGs), metal resistance genes (MRGs), and mobile genetic elements (MGEs). BC-nZVI modified the preference of MGEs to carry ARGs and MRGs, and the corrosion products of BC-nZVI could destroy cell structure, hinder electron transfer between cells, and weaken the association between ARGs, MRGs, and host bacteria. Functional genes analysis revealed that BC-nZVI down-regulated the abundance of genes affecting the transmission and metabolism of ARGs and MRGs, including type IV secretion systems, transporter systems, two-component systems, and multidrug efflux pumps. Furthermore, the BC-nZVI decreased genes related to flagella and pili production and cell membrane permeability, thereby hindering the transfer of ARGs, MRGs, and MGEs in the environment. Redundancy analysis demonstrated that changes in the microbial community induced by BC-nZVI were pivotal factors impacting the abundance of ARGs, MRGs, and MGEs. Overall, this study confirmed the efficacy of BC-nZVI in reducing resistance genes during swine manure composting, offering a promising environmental strategy to mitigate the dissemination of these contaminants.

Quantitative assessment, molecular docking and novel metabolic pathways reveal the interaction mechanisms between norfloxacin biodegradation and environmental implications

Norfloxacin (NOR) is widely used in medicine and animal husbandry, but its accumulation in the environment poses a substantial threat to ecological and human health. Traditional physical, chemical, and rudimentary biological methods often fall short in mitigating NOR contamination, necessitating innovative biological approaches. This study proposes an engineered bacterial consortium found in marine sediment as a strategy to enhance NOR degradation through inter-strain co-metabolism of diverse substrates. Strategically supplementing the engineered bacterial consortium with exogenous carbon sources and metal ions boosted the activity of key degradation enzymes like laccase, manganese peroxidase, and dehydrogenase. Iron and amino acids demonstrated synergistic effects, resulting in a remarkable 70.8% reduction in NOR levels. The innovative application of molecular docking elucidated enzyme interactions with NOR, uncovering potential biodegradation mechanisms. Quantitative assessment reinforced the efficiency of NOR degradation within the engineered bacterial consortium. Four metabolic routes are herein proposed: acetylation, defluorination, ring scission, and hydroxylation. Notably, this study discloses distinctive, co-operative metabolic pathways for NOR degradation within the specific microbial community. These findings provide new ways of understanding and investigating the bioremediation potential of NOR contaminants, which may lead to the development of more sustainable and effective environmental management strategies.

Exploring the promoting effect of nitrilotriacetic acid on hydroxyl radical and humification during magnetite-amended composting of sewage sludge

The OH production by adding magnetite (MGT) alone has been reported in composting. However, the potential of nitrilotriacetic acid (NTA) addition for magnetite-amended sludge composting remained unclear. Three treatments with different addition [control check (CK); T1: 5 % MGT; T2: 5 % MGT + 5 % NTA] were investigated to characterize hydroxyl radical, humification and bacterial community response. The NTA addition manifested the best performance, with the peak OH content increase by 52 % through facilitating the cycle of Fe(Ⅱ)/Fe(Ⅲ). It led to the highest organic matters degradation (22.3 %) and humic acids content (36.1 g/kg). Furthermore, NTA addition altered bacterial community response, promoting relative abundances of iron-redox related genera, and amino acid metabolism but decreasing carbohydrate metabolism. Structural equation model indicated that temperature and Streptomyces were the primary factors affecting OH content. The study suggests that utilizing chelators is a promising strategy to strengthen humification in sewage sludge composting with adding iron-containing minerals.

Diverse Applications of Two-Dimensional Correlation Spectroscopy (2D-COS)

This second of the two-part series of a comprehensive survey review provides the diverse applications of two-dimensional correlation spectroscopy (2D-COS) covering different probes, perturbations, and systems in the last two years. Infrared spectroscopy has maintained its top popularity in 2D-COS over the past two years. Fluorescence spectroscopy is the second most frequently used analytical method, which has been heavily applied to the analysis of heavy metal binding, environmental, and solution systems. Various other analytical methods including laser-induced breakdown spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, capillary electrophoresis, seismologic, and so on, have also been reported. In the last two years, concentration, composition, and pH are the main effects of perturbation used in the 2D-COS fields, as well as temperature. Environmental science is especially heavily studied using 2D-COS. This comprehensive survey review shows that 2D-COS undergoes continuous evolution and growth, marked by novel developments and successful applications across diverse scientific fields.

Synergistic improvement of humus formation in compost residue by fenton-like and effective microorganism composite agents

Improving the humification of compost through a synergistic approach of biotic and abiotic methods is of great significance. This study employed a composite reagent, comprising Fenton-like agents and effective microorganisms (EM) to improve humification. This composite reagent increased humic-acid production by 37.44 %, reaching 39.82 g kg-1, surpassing the control group. The composite reagent synergistically promoted micromolecular fulvic acid and large humic acid production. Collaborative mechanism suggests that Fenton-like agents contributed to bulk residue decomposition and stimulated the evolution of microbial communities, whereas EMs promoted highly aromatic substance synthesis and adjusted the microbial community structure. Sequencing analysis indicates the Fenton-like agent initiated compost decomposition by Firmicutes, and EM reduced the abundance of Virgibacillus, Lentibacillus, and Alcanivorax. Applied as an organic fertilizer in Brassica chinensis L. plantations, the composite reagent considerably improved growth and photosynthetic pigment content. This composite reagent with biotic and abiotic components provides a learnable method for promoting humification.

Exogenous additive ferric sulfate regulates sulfur-oxidizing bacteria in cow manure composting to promote carbon fixation

Enhancing carbon fixation in the composting process was of great significance in the era of massive generation of organic solid waste. In this study, the experimental results showed that the contents of dissolved organic matter (DOM) in the experimental group (CT) were 37.58% higher than those in the control group (CK). The CO2 emission peaked on day 5, and the value of CK was 1.34 times that of CT. Significant differences were observed between the contents of sulfur fractions in CT and CK. This phenomenon may be due to the suppression of sulfur-reducing gene expression in CT. On day 51 of composting, the abundance of sulfur-oxidizing bacteria (SOB) Rhodobacter (5.33%), Rhodovulum (14.76%), and Thioclava (23.83%) in CT was higher than that in CK. In summary, the composting fermentation regulated by Fe2(SO4)3 increased the sulfate content, enhanced the expression of sulfur-oxidizing genes and SOB, and ultimately promoted carbon sequestration during composting.

Gaining insight into the effect of laccase expression on humic substance formation during lignocellulosic biomass composting

The aim is to enhance lignin humification by promoting laccase activities which can promote lignin depolymerization and reaggregation during composting. 1-Hydroxybenzotriazole (HBT) is employed to conduct laccase mediator system (LMS), application of oxidized graphene (GO) in combination to strengthen LMS. Compared with control, the addition of GO, HBT, and GH (GO coupled with HBT) significantly improved laccase expression and activities (P < 0.05), with lignin humification efficiency also increased by 68.6 %, 36.7 %, and 107.8 %. GH treatment induces microbial expression of laccase by increasing the abundance and synergy of core microbes. The unsupervised learning model, vector autoregressive model and Mantel test function were combined to elucidate the mechanism of action of exogenous materials. The results showed that GO stabilized the composting environment on the one hand, and acted as a support vector to stabilize the LMS and promote the function of laccase on the other. In GH treatment, degradation of macromolecules and humification of small molecules were promoted simultaneously by activating the dual function of laccase. Additionally, it also reveals the GH enhances the humification of lignocellulosic compost by converting phenolic pollutants into aggregates. These findings provide a new way to enhance the dual function of laccase and promote lignin humification during composting. It could effectively achieve the resource utilization of organic solid waste and reduce composting pollution.

Effects of Fe3O4 NMs based Fenton-like reactions on biodegradable plastic bags in compost: New insight into plastisphere community succession, co-composting efficiency and free radical in situ aging theory

Biodegradable plastic bags (BPBs), meant for eco-friendly, often inadequately degrade in compost, leading to microplastic pollution. In this study, the effect of Fenton-like reaction with Fe3O4 nanoparticles (NMs) on the plastisphere microorganisms' evolution and the BPBs' aging mechanism was revealed by co-composting of food waste with BPBs for 40 days. The establishment of the Fenton-like reaction was confirmed, with the addition of Fenton-like reagent treatments resulting in an increase of 57.67% and 37.75% in H2O2 levels during the composting, compared to the control group. Moreover, the structural characterization reveals that increasing oxygen content continuously generates reactive free radicals on the surface, leading to the formation of oxidative cavities. This process results in random chain-breaking, significantly reducing molecular weights by 39.27% and 38.81%, thus showcasing a deep-seated transformation in the plastic's molecular structure. Furthermore, the microbial network suggested that the Fenton-like reaction enriched plastisphere keystone species, thus accelerating the BPBs' aging. Additionally, the Fenton-like reaction improved compost maturity and reduced greenhouse gas emissions. These results reveal the bio-chemical mechanisms of BPBs aging and random chain-breaking by the Fenton-like reaction, under alternating oxidative/anoxic conditions of composting and provide a new insight to resolve the BPBs' pollutions.

Synergizing biotechnology and natural farming: pioneering agricultural sustainability through innovative interventions

The world has undergone a remarkable transformation from the era of famines to an age of global food production that caters to an exponentially growing population. This transformation has been made possible by significant agricultural revolutions, marked by the intensification of agriculture through the infusion of mechanical, industrial, and economic inputs. However, this rapid advancement in agriculture has also brought about the proliferation of agricultural inputs such as pesticides, fertilizers, and irrigation, which have given rise to long-term environmental crises. Over the past two decades, we have witnessed a concerning plateau in crop production, the loss of arable land, and dramatic shifts in climatic conditions. These challenges have underscored the urgent need to protect our global commons, particularly the environment, through a participatory approach that involves countries worldwide, regardless of their developmental status. To achieve the goal of sustainability in agriculture, it is imperative to adopt multidisciplinary approaches that integrate fields such as biology, engineering, chemistry, economics, and community development. One noteworthy initiative in this regard is Zero Budget Natural Farming, which highlights the significance of leveraging the synergistic effects of both plant and animal products to enhance crop establishment, build soil fertility, and promote the proliferation of beneficial microorganisms. The ultimate aim is to create self-sustainable agro-ecosystems. This review advocates for the incorporation of biotechnological tools in natural farming to expedite the dynamism of such systems in an eco-friendly manner. By harnessing the power of biotechnology, we can increase the productivity of agro-ecology and generate abundant supplies of food, feed, fiber, and nutraceuticals to meet the needs of our ever-expanding global population.

Elucidating carbon conversion and bacterial succession by amending Fenon-like systems during co-composting of pig manure and branch

The essential point of current study was to investigate the effect of a Fenton-like system established by oxalic acid and Fe(II) on gas emission, organic matter decomposition and humification during composting. Branches were pretreated with Fenton reagents (0.02 M FeCl2·4H2O + 1.5 M H2O2) and then adding 10 % oxalic acid (OA). The treatments were marked as B1 (control), B2 (Fenton reagent), B3 (10% OA) and B4 (Fenton-like reagent). The results collected from 80 d of composting showed that adding Fenton-like reagent benefited the degradation of organic substances, as reflected by the total organic carbon and dissolved organic carbon, and the maximum decomposition rate was observed in B4. In addition, the Fenton-like reagent could improve the synthesis of humus characterized by complex and stable compounds, which was consistent with the spectral parameters (SUVA254, SUVA280, E253/E203 and Fourier transform-infrared indicators) of DOC. Furthermore, the functional microbial succession performance and linear discriminant effect size analyses provided microbial evidence of humification improvement. Notably, compared with the control, the minimum value of CH4 cumulation was reported in B4, which decreased by 30.44 %. Concluded together, the addition of a Fenton-like reagent composed by OA and Fe(II) is a practical way to improve the humification. Furthermore, the mechanisms related to the promotion of humification should be investigated from free radicals, functional genes, and metabolic pathways.

Catalytic degradation of antibiotic sludge to produce formic acid by acidified red mud

As complex and difficult-to-degrade persistent organic pollutants (POPs), antibiotics have caous damage to the ecological enused serivironment. Because of the difficult degradation of antibiotics, sewage and sludge discharged by hospitals and pharmaceutical enterprises often contain a large number of antibiotic residues. Therefore, the harmless and resourceful treatment of antibiotic sludge is very meaningful. In this paper, amoxicillin was selected as a model compound for antibiotic sludge. Acidified red mud (ARM) was used to degrade antibiotic sludge and produce hydrogen energy carrier formic acid in catalytic wet peroxidation system (CWPO). Based on various characterization analyses, the reaction catalytic mechanism was demonstrated to be the result of the non-homogeneous Fanton reaction interaction between Fe3O4 on the ARM surface and H2O2 in solution. Formic acid is the product of the decarboxylation reaction of amoxicillin and its degradation of various organic acids. The formic acid was produced up to 792.38 mg L-1, under the optimal conditions of reaction temperature of 90 °C, reaction time of 30 min, H2O2 concentration of 20 mL L-1, ARM addition of 0.8 g L-1, pH = 7, and rotor speed of 500 rpm. This research aims to provide some references for promoting red mud utilization in antibiotic sludge degradation.

Incorporating microbial inoculants to reduce nitrogen loss during sludge composting by suppressing denitrification and promoting ammonia assimilation

To address the challenge of increasing nitrogen retention in compost, this study investigated the effects of microbial communities on denitrification and ammonia assimilation during sludge composting by inoculating microbial inoculants. The results showed that the retention rates of total Kjeldahl nitrogen (TKN) and humic acid (HA) in MIs group (with microbial inoculants) were 4.94 % and 18.52 % higher than those in the control group (CK), respectively. Metagenomic analysis showed that Actinobacteria and Proteobacteria were identified as main microorganisms contributing to denitrification and ammonia assimilation. The addition of microbial agents altered the structure of the microbial community, which in turn stimulated the expression of functional genes. During cooling period, the ammonia assimilation genes glnA, gltB and gltD in MIs were 15.98 %, 24.84 % and 32.88 % higher than those in CK, respectively. Canonical correspondence analysis revealed a positive correlation between the dominant bacterial genera from the cooling stage to the maturity stage and the levels of NO3--N, NH4+-N, HA, and TKN contents. NH4+-N was positively correlated with HA, indicating NH4+-N might be incorporated into HA. Heat map and network analyses revealed NH4+-N as a key factor affecting functional genes of denitrification and ammonia assimilation, with Nitrospira identified as the core bacteria in the microbial network. Therefore, the addition of microbial agents could increase nitrogen retention and improve compost product quality.

Control of odorants in swine manure and food waste co-composting via zero-valent iron /H2O2 system

Odors have posed challenges to the advancement of aerobic composting. This work aims to identify the primary components responsible for odors and assess the effectiveness and mechanisms of the zero-valent iron/H2O2 system controlling various odorants in aerobic composting. Swine manure and food waste were used as composting materials, with the addition of zero-valent iron and hydrogen peroxide to mitigate odor emissions. Results revealed that odorants included ammonia, hydrogen sulfide, and 22 types of volatile organic compounds (VOCs), with ethyl acetate, heptane, and dimethyl disulfide being predominant. Among the odorants emitted, ammonia accounted for 75.43%, hydrogen sulfide for 0.09%, and identified VOCs for 24.48%. The ZVI/H2O2 system showed a significant reduction in ammonia and VOCs emission, with the reduction of 51% (ammonia) and 41.3% (VOCs) respectively, primarily observed during the thermophilic period. The occurrence of Fenton-like reactions and changes in key microbial populations were the main mechanisms accounting for odor control. The occurrence of Fenton-like reaction was confirmed by X-ray photoelectron spectroscopy and reactive oxygen detection, showing the oxidation of zero-valent iron by H2O2 to higher valence elemental iron, and the simultaneous production of ·OH. Microbial analysis indicated that an enrichment of specific microorganisms with Bacillus contributed to feammonx and Bacillaceae contributed to organic biodegradation. Redundancy analysis highlighted the role of key microbial species (Bacillaceae, Bacillus, and Ureibacillus) in effectively reducing the level of ammonia and volatile organic compounds. These novelty findings illustrated that the potential of this system is promising for controlling the emission of odorants and aerobic composting reinforcement.

Artificial Humic Substances as Biomimetics of Natural Analogues: Production, Characteristics and Preferences Regarding Their Use

Various processes designed for the humification (HF) of animal husbandry wastes, primarily bird droppings, reduce their volumes, solve environmental problems, and make it possible to obtain products with artificially formed humic substances (HSs) as analogues of natural HSs, usually extracted from fossil sources (coal and peat). This review studies the main characteristics of various biological and physicochemical methods of the HF of animal wastes (composting, anaerobic digestion, pyrolysis, hydrothermal carbonation, acid or alkaline hydrolysis, and subcritical water extraction). A comparative analysis of the HF rates and HS yields in these processes, the characteristics of the resulting artificial HSs (humification index, polymerization index, degree of aromaticity, etc.) was carried out. The main factors (additives, process conditions, waste pretreatment, etc.) that can increase the efficiency of HF and affect the properties of HSs are highlighted. Based on the results of chemical composition analysis, the main trends and preferences with regard to the use of HF products as complex biomimetics are discussed.

Antibiotic resistance gene profiles and evolutions in composting regulated by reactive oxygen species generated via nano ZVI loaded on biochar

In this study, nano zero-valent iron loaded on biochar (BC-nZVI) was analyzed for its effects on antibiotic resistance genes (ARGs) in composting. The results showed that BC-nZVI increased reactive oxygen species (ROS) production, and the peak values of H2O2 and OH were 22.95 % and 55.30 % higher than those of the control group, respectively. After 65 days, the relative abundances of representative ARGs decreased by 56.12 % in the nZVI group (with BC-nZVI added). An analysis of bacterial communities and networks revealed that Actinobacteria, Proteobacteria, and Firmicutes were the main hosts for ARGs, and BC-nZVI weakened the link between ARGs and host bacteria. Distance-based redundancy analysis showed that BC-nZVI altered the microbial community structure through environmental factors and that most ARGs were negatively correlated with ROS, suggesting that ROS significantly affected the relative abundance of ARGs. According to these results, BC-nZVI showed potential for decreasing the relative abundance of ARGs in composting.

Effect of the addition of biochar and wood vinegar on the morphology of heavy metals in composts

In the experiment, the morphology of heavy metals (Pb, Cr, Cd, and Ni, HMs) was characterized using flame atomic absorption spectroscopy. In addition, Fourier transform infrared spectroscopy (FTIR) and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM) were used to characterize the correlation between environmental factors and metal morphology in the rotting compost from several angles. The results showed that the humus treated with wood vinegar solution had a high degree of humification and rich aromatic structure. FTIR spectroscopy confirmed that the degree of humus aromatization gradually increased during the composting process, which enhanced the complexation of humus (HS) with HMs but had less effect on Ni. In addition, the optimum concentration of wood vinegar (WV) was determined to be 1.75%. The results of the study showed that in the Pb passivation treatment group, the proportion of soluble (Red) and exchangeable states (Exc) converted to oxidized (Oxi) and residual states (Res) was 8%, 14%, 6%, 1%, and 12% in the CK, T1, T2, T3, and T4 treatment groups, respectively; in the Cr passivation treatment group, the proportion of Cr-Red and Cr-Exc converted to oxidized and residual states was 31%, 33%, 25%, 29%, and 25%; in the Cd passivation treatment group, the proportions of Cd-Red and Cd-Exc converted to oxidized and residual states were 5%, 15%, 4%, 9%, and 11%, respectively; whereas the Ni treatment group did not show any significant passivation effect. The proportion of Pb-Oxi was relatively stable, Cr-Oxi was converted to Cr-Res, whereas Cd showed the conversion of Cd-Oxi to Cd-Exc. SUVA254 and SUVA280 showed significant positive correlations with Pb-Res, Cr-Res and Ni-Res, and significant positive correlations with moisture content (MC); whereas MC was significantly negatively correlated with each form of HMs. Total potassium (TK), total nitrogen (TN), and both carbon (TOC) were negatively correlated with Pb-Res and Pb-Exc. Structural equation modeling verified the relationship between environmental factors and HMs, and the composting results showed that the addition of biochar (BC) and a higher percentage of WV could increase compost decomposition and passivate HMs to improve its agronomic function.

Insights into antibiotic resistance gene abundances and regulatory mechanisms induced by ionic liquids during composting

This study investigated the regulatory mechanism of the evolution of antibiotic resistance genes (ARGs) during the composting process with sawdust and cow manure as raw materials using ionic liquids (ILs) pretreatment. The results showed that genes of MLS, chloramphenicol, tetracycline, beta - lactam as composting gradually decreased. From day0 to day3, MLS in control group (CK) and experimental group (T) decreased by 25.62% and 26.66%, respectively. Tetracycline decreased by 7.21% in CK and by 7.86% in T. Chloramphenicol decreased by 2.85% in CK and 3.34% in T. Beta-lactam decreased by 1.95% in Ck and by 3.69% in T. Mechanism studies have shown that ILs can effectively decompose extracellular polymeric substances (EPS) and enhance lactose dehydrogenase (LDH) release, resulting in ARGs release and elimination. Meanwhile, ILs pretreatment can inhibit growth of some ARGs hosts, especially Firmicutes, resulting in decreased ARGs. Moreover, metabolic pathways and related genes take part in ARGs transmission were down regulated, leading to decreased ARGs.

Regulating sludge composting with percarbonate facilitated the methylation and detoxification of arsenic mediated via reactive oxygen species

This study purposed to demonstrate the impact of reactive oxygen species (ROS) on arsenic detoxification mechanism in sludge composting with percarbonate. In this study, sodium percarbonate was used as an additive. Adding sodium percarbonate increased the content of H2O2 and OH, which the experimental group (SPC) was higher than the control group (CK). In addition, it decreased the bioavailability of arsenic by 19.10%. Metagenomic analysis found that Firmicutes and Pseudomonas took an active part in the overall compost as the dominant bacteria of arsenic methylation. ROS positively correlated with arsenic oxidation and methylation genes (arsC, arsM), with the gene copy number of arsC and arsM increasing to 7.74 × 1012, 5.24 × 1012 in SPC. In summary, the passivation of arsenic could be achieved by adding percarbonate, which promoted the methylation of arsenic, reduced the toxicity of arsenic, and provided a new idea for the harmless management of sludge.

Bubble-propelled micromotors for ammonia generation

Micromotors have emerged as promising tools for environmental remediation, thanks to their ability to autonomously navigate and perform specific tasks at the microscale. In this study, we present the development of MnO2 tubular micromotors modified with laccase for enhanced oxidation of organic pollutants by providing an additional oxidative catalytic pathway for pollutant removal. These modified micromotors exhibit efficient ammonia generation through the catalytic decomposition of urea, suggesting their potential application in the field of green energy generation. Compared to bare micromotors, the MnO2 micromotors modified with laccase exhibit a 20% increase in rhodamine B degradation. Moreover, the generation of ammonia increased from 2 to 31 ppm in only 15 min, evidencing their high catalytic activity. To enable precise tracking of the micromotors and measurement of their speed, a deep-learning-based tracking system was developed. Overall, this work expands the potential applicability of bio-catalytic tubular micromotors in the energy field.

Transmission and regulation insights into antibiotic resistance genes in straw-sludge composting system amended with calcium peroxide

This study developed a Fenton-like system by adding calcium peroxide (CaO2) to a composting system containing straw and sludge. The objective was to examine the influence of antibiotic resistance genes (ARGs) and the structure of the bacterial community. The findings indicated that the inclusion of CaO2 facilitated the reduction of ARGs. ARGs abundance in the test group (T) with CaO2 was 19.02% lower than that in the control check group (CK) without CaO2, and the abundance of ARGs in both groups after composting was lower than the initial abundance. Additionally, the structure of bacterial community in both groups underwent significant changes. Redundancy analysis (RDA) revealed that the CaO2-induced Fenton-like reaction predominantly affected temperature, pH, and the bacterial community by means of reactive oxygen species (ROS). In conclusion, the addition of CaO2 enhanced the removal of ARGs from sewage-sludge and improved compost quality in the composting.

Exolaccase Propels Humification to Decontaminate Bisphenol A and Create Humic-like Biostimulants

Exolaccase-propelled humification (E-PH) helps eliminate phenolic pollutants and produce macromolecular precipitates. Herein, we investigated the influencing mechanism of 12 humic precursors (HPs) on exolaccase-enabled bisphenol A (BPA) decontamination and humification. Catechol, vanillic acid, caffeic acid, and gentian acid not only expedited BPA removal but also created large amounts of copolymeric precipitates. These precipitates had rich functional groups similar to natural humic substances, which presented great aromatic and acidic characteristics. The releasing amounts of BPA monomer from four precipitates were 0.08-12.87% at pH 2.0-11.0, suggesting that BPA-HP copolymers had pH stability. More excitingly, certain copolymeric precipitates could stimulate the growth and development of radish seedlings. The radish growth-promotion mechanisms of copolymers were involved in two aspects: (1) Copolymers interacted with root exudates to accelerate nutrient uptake; (2) Copolymers released auxins to provoke radish growth. These results may provide an innovative strategy for decontaminating phenolic pollutants and yielding humic-like biostimulants in E-PH.

Iron reduction in composting environment synergized with quinone redox cycling drives humification and free radical production from humic substances

The aim of this paper was to investigate the influence of Fe (III) on humification and free radicals evolution. The experimental data showed that the experimental group (CT) with Fe₂(SO₄)₃ had a better degree of humification than the control group (CK). The humic substances (HS) content was 10% higher in CT (23.94 mg·g^-1) than in CK (21.54 mg·g^-1) in the final. Fe (III) contributed significantly to the formation of free radicals in HS. The amount of H₂O₂ in CT increased to 74.8 mmol·kg^-1, while CK was only 46.5 mmol·kg^-1. The content of semiquinone free radical was 10.32×10¹¹ spins/mm³ in CT, 5.11×10¹¹ spins/mm³ in CK in the end. Several iron-reducing bacteria were detected in composting, among which Paenibacillus was dominant. The above findings suggested that the application of Fe₂(SO₄)₃ enhanced the iron reduction synergistic quinone redox cycling and promoted the generation of free radicals during the humification of composting.

Performances of antibiotic resistance genes profile upon the action of biochar-activated peroxydisulfate in composting

In this study, the amendment of biochar-activated peroxydisulfate during composting to remove antibiotic resistance genes (ARGs) by direct (microbial community succession) and indirect methods (physicochemical factors) was analyzed. When implementing indirect methods, the synergistic effect of peroxydisulfate with biochar optimized the physicochemical habitat of compost, maintaining its moisture within a range of 62.95%-65.71%, and a pH of 6.87-7.73, and causing the compost to mature 18 days earlier than the control groups. The direct methods caused the optimized physicochemical habitat to adjust the microbial communities and reduce the abundance of most of the ARG host bacteria (Thermopolyspora, Thermobifida, and Saccharomonospora), thus inhibiting this substance's amplification. Heatmap analysis confirmed the necessary connection between physicochemical factors, microbial communities, and ARGs. Moreover, a mantel test confirmed the direct significant effect of the microbial communities on ARGs and the indirect significant effect of physicochemical factors on ARGs. The results showed that the abundance of more ARGs was down-regulated at the end of composting and regulated by biochar-activated peroxydisulfate, especially for the abundance of AbaF, tet(44), golS, and mryA, which was significantly decreased by 0.87-1.07 fold. These results provide new insights into the removal of ARGs during composting.

Elaborating the role of rhamnolipids on the formation of humic substances during rice straw composting based on Fenton pretreatment and fungal inoculation

Composting is a green and sustainable way to dispose and reuse agricultural wastes, but the low degradation rate during composting hinders its application. This study was conducted to explore the effect of added surfactant rhamnolipids after Fenton pretreatment and inoculation of fungi (Aspergillus fumigatus) into the compost on the formation of humic substances (HS) during rice straw composting, and explored the effect of this method. The results showed that rhamnolipids speeded up the degradation of organic matter and HS formation during composting. Rhamnolipids promoted the generation of lignocellulose-degrading products after Fenton pretreatment and fungal inoculation. The differential products benzoic acid, ferulic acid, 2, 4-Di-tert-butylphenol and syringic acid were obtained. Additionally, key fungal species and modules were identified using multivariate statistical analysis. Reducing sugars, pH, and total nitrogen were the key environmental factors that affected HS formation. This study provides a theoretical basis for the high-quality transformation of agricultural wastes.

Maleic anhydride promotes humus formation via inducing functional enzymes response in composting

The purpose of this paper was to explore the promotion of maleic anhydride on the polymerization of precursors into humus in composting, and analyze the changes of key functional enzymes. The results showed that the content of humus in the treatment group added maleic anhydride (MAH) was higher than that in the control check (CK). The decrease rate of humus precursor concentration of MAH was also higher than that of CK. In MAH, the activities of laccase and tyrosinase were improved, thus enhanced the catalytic conversion of humus precursors. The analysis of bacterial community showed that maleic anhydride optimized the community structure of humification functional enzymes producing bacteria, with the most obvious increase of Firmicutes. In conclusion, this study provided theoretical supports for the introduction of maleic anhydride into the compost system to promote the polymerization of precursors to form humus.

Reactive oxygen species accelerate humification process during iron mineral-amended sludge composting

The production of hydroxyl radicals (OH) has been documented during composting. However, the effect of OH on composting efficiency remains unclear. Here, iron mineral supplemented thermophilic composting (imTC) is proposed and demonstrated for enhancing OH production and accelerating the maturation of composting. The results indicated that the maximum OH production of imTC was 1922.74 μmol·kg^-1, which increased by 1.39 times than that of ordinary thermophilic composting (oTC). Importantly, the increase of OH could greatly enhance organic matter degradation and humic substances formation during imTC, resulting in shorting the maturity time by 25 %. Enrichment of laccase-producing bacteria resulted in higher laccase activity (31.85 U·g^-1) in imTC compared with oTC (23.82 U·g^-1), which may have contributed to the higher level of humification in imTC treatment. This work, for the first time, proposes a feasible strategy for improving composting efficiency through the regulation of OH production during aerobic composting.

Quinone redox cycling drives lignocellulose depolymerization and degradation in composting environments based on metagenomics analysis

In this study, the effect of Fe³⁺ on the quinone redox cycling driving lignocellulosic degradation in composting systems was investigated. The results showed that the degradation rates of cellulose, hemicellulose, and lignin were higher in the experimental group (CT) with Fe₂(SO₄)₃ addition than in the blank group (CK) (CT, 52.55 %, 45.14 %, 56.98 %; CK, 49.63 %, 37.34 %, 52.3 %). Changes in the abundance of key enzymes for quinone reduction (AA3_1, AA3_2, AA6) and the structural succession of microbial communities were analyzed by metagenomic analysis. Among them, Fe₂(SO₄)₃ had the most significant effect on AA3_2, with an approximately 8-fold increase in abundance compared to the beginning of composting. The dominant phylum in the composting process was Actinobacteria. In conclusion, the addition of Fe₂(SO₄)₃ contributed to the quinone redox cycling and effectively improved the degradation rate of lignocellulose in composting.

3D hierarchical LDHs-based Janus micro-actuator for detection and degradation of catechol

Micro/nanomotors that combine the miniaturization and autonomous motion have attracted much research interest for environmental monitoring and water remediation. However, it is still challenging to develop a facile route to produce bifunctional micromotors that can simultaneously detect and remove organic pollutants from water. Herein, we developed a novel Janus micromotor with robust peroxide-like activity for simultaneously colorimetric detection and removal of catechol from water. Such laccase (Lac) functionalized Janus micromotor consisted of calcined MgAl-layered double hydroxides (MgAl-CLDHs) nanosheets and Co₃O₄-C nanoparticles (Lac-MgAl-CLDHs/Co₃O₄-C), revealing unique 3D hierarchical microstructure with highly exposed active sites. The obtained Janus micromotors exhibited autonomous motion with a maximum velocity of 171.83 ± 4.07 µm/s in the presence of 7 wt% H₂O₂ via a chemical propulsion mechanism based on the decomposition of H₂O₂ by Co₃O₄-C layer on the hemisphere surface of Janus micromotors. Owing to the combination of autonomous motion and high peroxide-like activity, Lac-MgAl-CLDHs/Co₃O₄-C Janus micromotors could sensitively detect catechol with the limit of detection of 0.24 μM. In addition, such Janus micromotors also could quickly degrade catechol by •OH generated from a Fenton-like reaction. It is a first step towards using autonomous micromotors for highly selective, sensitive, and facile detection and quick removal of catechol from water.

Independent and combined effects of biochar and microbial agents on physicochemical parameters and microbial community succession during food waste composting

This study evaluated the independent and combined effects of biochar and microbial agents on food waste composting. The results indicated that combined addition increased the peak temperature to 63.5 °C and extended the thermophilic periods to 8 days, resulting in the highest organic matter degradation rate (12.7%). Analysis of enzymatic activity indicated that combined addition increased urease and dehydrogenase activity by 22.9% and 26.5%. Furthermore, the degradation of volatile fatty acids also increased by 37.4% with combined addition. Microbial analysis demonstrated that combined addition effectively increased the relative abundances of Enterobacter, Sphingobacterium and Aspergillus, which could be attributed to the optimal environment provided by biochar and stimulation of microbial agents. Moreover, correlation analysis showed a strong interaction between the microbial community and environment with combined addition. In general, combined addition could be beneficial for composting based on the synergistic effects of biochar and inoculation on microorganism.

Oxidative degradation of UV-irradiated polyethylene by laccase-mediator system

Polyethylene (PE) is one of the most widely used plastics. However, the chemical inertness, inefficient recycling, and random landfilling of PE waste have caused serious pollution to the natural environment. In this study, a series of laccase-mediator systems (LMS) were constructed by combination of two laccases from Botrytis aclada (BaLac) and Bacillus subtilis (BsLac) with three synthetic mediators (ABTS, HBT, and TEMPO) to oxidize LDPE films (UVPE) pretreated with high-temperature UV irradiation. Scanning electron microscopy showed aging phenomena such as etching, fragmentation, and cracking on the surface of the UVPE films after LMS incubation. The FTIR results showed that LMS-UVPE added new oxygen-containing functional groups such as -OH, -CO, and CC. High-temperature gel chromatography confirmed that the average reduction in weight-average molecular weight (Mw) was approximately 40% for the BaLac experimental group. GC-MS analysis showed the presence of oxygen-containing products, such as aldehydes, ketones, and alcohols, in the reaction mixture. To verify the oxidation process UVPE degradation by LMS, we inferred three possible pathways by combined analysis of the oxidation products of LMS on UVPE and model substrates oleic acid and squalene.

Synergistic metabolism of carbon and nitrogen: Cyanate drives nitrogen cycle to conserve nitrogen in composting system

In this study, HCO₃^- was used as a co-substrate for cyanate metabolism to investigate its effect on nitrogen cycle in composting. The results showed that the carbamate content in experimental group (T) with HCO₃^- added was higher than that in control group (CP) during cooling period. Actinobacteria and Proteobacteria were the dominant phyla for cyanate metabolism, and the process was mediated by cyanase gene (cynS). The cynS abundance was 16.6% higher in T than CP. In cooling period, the nitrification gene hao in T was 8.125% higher than CP. Denitrification genes narG, narH, nirK, norB, and nosZ were 25.64%, 35.33%, 45.93%, 36.62%, and 36.12% less than CP, respectively. The nitrogen fixation gene nifH in T was consistently higher than CP in the late composting period. Conclusively, cyanate metabolism drove the nitrogen cycle by promoting nitrification, nitrogen fixation, and inhibiting denitrification, which improved nitrogen retention and compost quality.

Exolaccase-boosted humification for agricultural applications

Globally, phenolic contaminants have posed a considerable threat to agro-ecosystems. Exolaccase-boosted humification may be an admirable strategy for phenolic detoxification by creating multifunctional humic-like products (H-LPs). Nonetheless, the potential applicability of the formed H-LPs in agricultural production is still overlooked. This review describes immobilized exolaccase-enabled humification in eliminating phenolic pollutants and producing artificial H-LPs. The similarities and differences between artificial H-LPs and natural humic substances (HSs) in chemical properties are compared. In particular, the agronomic effects of these reproducible artificial H-LPs are highlighted. On the basis of the above summary, the granulation process is employed to prepare granular humic-like organic fertilizers, which can be applied to field crops by mechanical side-deep fertilization. Finally, the challenges and perspectives of exolaccase-boosted humification for practical applications are also discussed. This review is a first step toward a more profound understanding of phenolic detoxification, soil improvement, and agricultural production by exolaccase-boosted humification.

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Exolaccase-initiated humification is conductive to phenolic detoxification

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Multiple humic-like products are created in exolaccase-boosted humification

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Similarities and differences between artificial and natural humus are disclosed

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Humic-like products can be used to sustain soil health and increase crop yield

Impacts of size reduction and alkaline-soaking pretreatments on microbial community and organic matter decomposition during wheat straw composting

This study assessed the impacts of size reduction and alkaline-soaking pretreatments on microbial community shifts and organic matter decomposition in wheat straw composting. Bacterial communities were altered by alkaline soaking rather than size reduction, while fungal communities were altered by both pretreatments. Alkaline-soaking pretreatment promoted lignocellulosic saccharification and humification. A combination of both pretreatments increased the proportion of the fungal genus Coprinopsis (39%) at the early stage and promoted the proliferation of Ornithincoccus (15%) at the late stage. This facilitated the mineralization of ammonium N from amino acids; decreased the total lipids, free fatty acids, and nitrate N contents; and greatly improved the germination index of the final composting product to a high level of 149% as tested with radish seeds. The findings demonstrate that the combined application of size reduction and alkaline-soaking pretreatments is an effective strategy for improving the product quality of wheat straw compost.

Extensive production and evolution of free radicals during composting

The production of free radicals has been widely documented in natural systems, where they play an important role in most organic matter and contaminants transformation. Here, the production and evolution of free radicals were systematically investigated during composting. Results indicated that multiple reactive oxygen species and environmentally persistent free radicals (G-factor 2.003-2.004) were generated with dynamic changes during composting. The ·OH yield fluctuated significantly with a maximum content of 365.7-1,262.3 μmol/kg at the thermophilic phase of composting, which was closely correlated with the changes of Fe (II) (Pearson's r = 0.928-0.932) and the electron-donating capacity of humus (Pearson's r = 0.958-0.896) during composting. Further investigation suggested that microorganisms driven iron/humus redox conversion could contribute to the production and dynamic changes of free radical during composting. These findings highlight the abiotic processes involving free radicals, and provide a new perspective for humification and contaminants removal during composting.

In-situ generation of H2O2 by zero valent iron to control depolymerization of lignocellulose in composting niche

Lignocellulosic degradation is a bottleneck of bioconversion during the composting process. In-situ generation of H₂O₂ in the composting system was an ideal method for efficiently promoting lignocellulase degradation, and zero valent iron (ZVI) was concerned because it can generate H₂O₂ by reducing dissolved oxygen. This study focused on the effects of ZVI treatment on lignocellulose degradation, microbial communities, and carbohydrate-active enzymes (CAZymes) genes during composting. Its results indicated that ZVI increased H₂O₂ content during composting, accompanied by the formation of •OH. The degradation rates of lignin, cellulose and hemicellulose in ZVI group (20.77%, 30.35% and 44.7%) were significantly higher than in CK group (17.01%, 26.12% and 38.5%). Metagenomic analysis showed that ZVI induced microbial growth that favored lignocellulose degradation, which increased the abundance of Actinobacteria and Firmicutes but reduced Proteobacteria. At the genus level, the abundance of Thermomonospora, Streptomyces, and Bacillus significantly increased. In addition, glycoside hydrolases and auxiliary activities were important CAZymes families of lignocellulose degradation, and their abundance was higher in the ZVI group. Redundancy analysis showed that the increased H₂O₂ and •OH content was a critical factor in improving lignocellulose degradation. Overall, H₂O₂ as a co-substrate enhanced the enzymatic efficiency, •OH unspecifically attacked lignocellulose, and the increase in functional microbial abundance was the main reason for promoting lignocellulose degradation in composting.

Exploring the effects of heavy metal passivation under Fenton-like reaction on the removal of antibiotic resistance genes during composting

This study aims to explore the succession of microbes carrying antibiotic resistance genes (ARGs), the relationship between heavy metal speciation and ARGs via Fenton-like reaction during composting. The results indicated that the passivation of Cu and Ni was more prominent, and the Fenton-like reaction promoted exceptionally the passivation of Zn, Ni and Mn. The removals of macrolides-lincosamids-streptogramins (MLS), aminoglycoside and tetracycline resistance genes were induced with the composting process, but the relative abundance of bacitracin resistance genes increased. Additionally, Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were main carriers and disseminators of ARGs, and the Fenton-like reaction improved the contribution degree of Proteobacteria to bacitracin, tetracycline and aminoglycoside resistance genes. Redundancy analysis revealed the passivation of heavy metal contributed to the removal of tetracycline, MLS and aminoglycoside resistance genes. Conclusively, the Fenton-like reaction promoted the passivation of Zn, Ni and Mn, and controlled the abundance of bacitracin resistance genes in composting.

Insights into the Applications of Extracellular Laccase-Aided Humification in Livestock Manure Composting

Traditional composting is a well-suited biotechnology for on-farm management of livestock manure (LM) but still leads to the release of toxic micropollutants and imbalance of nutrients. One in situ exoenzyme-assisted composting has shown promise to ameliorate the agronomical quality of end products by improving humification and polymerization. The naturally occurring extracellular laccase from microorganisms belongs to a multicopper phenoloxidase, which is verified for its versatility to tackle micropollutants and conserve organics through the reactive radical-enabled decomposition and polymerization channels. Laccase possesses an indispensable relationship with humus formation during LM composting, but its potential applications for the harmless disposal and resource utilization of LM have until now been overlooked. Herein, we review the extracellular laccase-aided humification mechanism and its optimizing strategy to maintain enzyme activity and in situ production, highlighting the critical roles of laccase in treating micropollutants and preserving organics during LM composting. Particularly, the functional effects of the formed humification products by laccase-amended composting on plant growth are also discussed. Finally, the future perspectives and outstanding questions are summarized. This critical review provides fundamental insights into laccase-boosted humification that ameliorates the quality of end products in LM composting, which is beneficial to guide and advance the practical applications of exoenzyme in humification remediation, the carbon cycle, and agriculture protection.

Signature of dissolved organic matter and microbial communities based on different oxygen levels response during distillers dried grains with solubles plus sugarcane pith co-fermentations

The objective of this study was to investigate the relationship between dissolved organic matter (DOM) and microbial communities during the co-fermentation of distillers dried grains with solubles (DDGS) and sugarcane pith at different oxygen levels. In aerobic fermentation (AF), the content of DOM decreased from 32.61 mg/g to 14.14 mg/g, and decreased from 32.61 mg/g to 30.83 mg/g in anaerobic fermentation (ANF). Phenols and alcohols were consumed first in AF, while lipids and proteins were consumed first in ANF. Degradation rates of cellulose, hemicellulose and lignin in AF (6.67%, 39.93%, 36.50%) were higher than those in ANF (0.69%, 18.36%, 9.12%). Firmicutes, Actinobacteriota and Ascomycota were the main phyla in community. Distance-based redundancy analysis showed that pH, organic matter (OM) and DOM were the main driving factors of microbial community succession.

Artificial intelligence modeling and molecular docking to analyze the laccase delignification process of rice straw by Comamonas testosteroni FJ17

The laccase enzymatic characteristics and delignification processes of rice straw by Comamonas testosteroni FJ17 were investigated. Artificial intelligence modeling and molecular docking revealed the specific functional properties involved in the interaction between laccase and lignin compounds with a maximum laccase activity of 2016.7 U L^-1 at 24 h. Scanning electron microscopy and X-ray diffractometer analysis confirmed that laccase caused fractures and holes on the surface of rice straw, where crystallinity decrease from 45.3 to 39.9%, and lignin content decreased from 19.0 to 10.3%. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry analysis showed that the main delignification process for laccase was via β-o-4 and α-aryl ether cleavage, which generated several small molecular products. The laccase gene was cloned and bioinformatics analysis presented 317 amino acids with a predicted molecular weight of 33.13 kDa. Finally, laccase protein was found to have low binding energies with all lignin compounds tested, and lignin compounds were oxidized by laccase through hydrogen-bonding interactions with the amino acid residues.

Elaboration of a Phytoremediation Strategy for Successful and Sustainable Rehabilitation of Disturbed and Degraded Land

Humans are dependent upon soil which supplies food, fuel, chemicals, medicine, sequesters pollutants, purifies and conveys water, and supports the built environment. In short, we need soil, but it has little or no need of us. Agriculture, mining, urbanization and other human activities result in temporary land-use and once complete, used and degraded land should be rehabilitated and restored to minimize loss of soil carbon. It is generally accepted that the most effective strategy is phyto-remediation. Typically, phytoremediation involves re-invigoration of soil fertility, physicochemical properties, and its microbiome to facilitate establishment of appropriate climax cover vegetation. A myco-phytoremediation technology called Fungcoal was developed in South Africa to achieve these outcomes for land disturbed by coal mining. Here we outline the contemporary and expanded rationale that underpins Fungcoal, which relies on in situ bio-conversion of carbonaceous waste coal or discard, in order to explore the probable origin of humic substances (HS) and soil organic matter (SOM). To achieve this, microbial processing of low-grade coal and discard, including bio-liquefaction and bio-conversion, is examined in some detail. The significance, origin, structure, and mode of action of coal-derived humics are recounted to emphasize the dynamic equilibrium, that is, humification and the derivation of soil organic matter (SOM). The contribution of plant exudate, extracellular vesicles (EV), extra polymeric substances (EPS), and other small molecules as components of the dynamic equilibrium that sustains SOM is highlighted. Arbuscular mycorrhizal fungi (AMF), saprophytic ectomycorrhizal fungi (EMF), and plant growth promoting rhizobacteria (PGPR) are considered essential microbial biocatalysts that provide mutualistic support to sustain plant growth following soil reclamation and restoration. Finally, we posit that de novo synthesis of SOM is by specialized microbial consortia (or ‘humifiers’) which use molecular components from the root metabolome; and, that combinations of functional biocatalyst act to re-establish and maintain the soil dynamic. It is concluded that a bio-scaffold is necessary for functional phytoremediation including maintenance of the SOM dynamic and overall biogeochemistry of organic carbon in the global ecosystem