Biodegradation最新文献

The presence of emerging contaminants in wastewater remains a hot topic of environmental concern due to their persistence, even at low concentrations. Biological treatment appears as an easy technique to implement, but its efficiency could decrease face to the recalcitrant pollutants. Therefore, this study aimed to investigate the synergistic effect between the Gliding arc plasma (Glidarc) and biodegradation (using a microbial consortium) routes for the degradation of Reactive Red 120 (RR120), as the model pollutant organic dye. Three bacterial species, including Staphylococcus aureus, Escherichia coli and Vibrio cholerae, were isolated on the surface waters, and combined into a consortium. RR120 (50–200 mg L⁻¹) inhibited the microbial growth of each bacterial specie (until 99% for S. aureus at 4.2 × 109 CFU mL⁻¹, 82% for E. coli at 6.8 × 10⁹ CFU mL⁻¹, 72% for V. cholerae at 8.0 × 10⁶ CFU mL⁻¹). Treatment using the consortium alone degraded 58% of RR120 (50 mg L⁻¹) after 24 h of incubation, with a first-order kinetic constant of 0.032 h⁻¹. To enhance this biological performance, RR120 solution was pre-treated using glidarc plasma for short times (5 and 10 min), resulting in an increase in the BOD₅/COD ratio, which leading to the increase of the biodegradability. Under plasma post-discharge conditions with the microbial consortium, the biodegradation rate of RR120 reached 89% after 24 h of incubation, with a kinetic constant of 0.080 h⁻¹. The biodegradation mechanism suggests that the process is initiated by the adsorption (approximately 34%), followed by microbial metabolism. This work shows that the microbial metabolism is significantly facilitated (catalysed) under plasma post-discharge conditions and highlights the economic benefit of the coupling both processes.

Deinococcus indicus DR1, a rod-shaped bacterium isolated from the Dadri wetlands (Uttar Pradesh, India), tolerates ionizing radiation and arsenic. However, the molecular basis of its wider heavy-metal resilience remains unclear, particularly for 1017 of the 4128 proteins still annotated as hypothetical. The aim of this study is to perform a proteome-wide structural and functional survey to address this gap. All 4128 proteins were modeled with AlphaFold2, yielding very-high-confidence structures of predicted local distance difference test scores ≥ 90 for 2145 sequences. CATH and InterPro analysis assigned domains to 2735 proteins. Functions were predicted by combining DeepFRI (graph neural-network), MorphologFinder (Foldseek coupled with EggNOG-Mapper), and existing GenBank annotations. Structural classification revealed domains involved in arsenic resistance properties. Functional annotation identified metal binding proteins. Recurrent domain architectures that include P-loop NTPases, Rossmann folds, GNAT acetyl-transferases, and sensor modules point to coordinated redox regulation and efflux pathways. The integrated workflow suggests that more than 100 previously uncharacterized proteins are associated with diverse metal-related functions including metal binding, cofactor utilization, transport, and detoxification across chromium, cobalt, copper, iron, manganese, molybdenum, nickel, and zinc. This indicates the presence of additional metal-associated proteins beyond the known arsenic-resistance (ars) gene cluster. However, their functional roles require experimental validation. Twenty high-confidence metal-binding candidates were prioritized for experimental validation through expression, mutagenesis, and gene-knockout studies. All structural models, domain assignments, and query tools are available at https://deinococcus.in, providing a resource for future investigations of heavy-metal tolerance in this organism.

Heavy metals (HMs) toxicity, such as nickel (Ni), has significantly reduced crop productivity and threatens human health, while efficient and widely applicable mitigation techniques remain underexplored. Vermicompost is an effective organic amendment to improve soil fertility and increase crop growth under HMs contamination; however, its derived biochar has not been extensively used to remediate Ni phytotoxicity. Hence, this study evaluated the ability of vermicompost (VC) and its derived biochar (VCB) in restricting nickel (Ni) bioaccumulation and growth improvement of wheat.The Ni toxicity decreased plant growth, physiological functions, and antioxidant capacity, along with yield parameters. Moreover, soil DTPA extractable Ni, Ni concentration in root and shoot and bioaccumulation factors significantly increase in Ni-contaminated soil (100 and 200 mg Ni kg⁻¹) compared with control (0 mg Ni kg⁻¹) soil. In contrast, the application of VC and VCB to soils containing 100 and 200 mg Ni kg⁻¹ significantly increased dry biomass (17%–25%), chlorophyll a and b (24%–43%), carotenoids (15%–30%), root volume (17%–35%), and 100-grain yield (15%–29%) compared with their corresponding Ni-only treatments. Among VC and VCB, VCB showed more prominent results in decreasing proline (12%) and H₂O₂ (44%) contents and enhancing CAT (45%) and POD (53%) activities under both 100 and 200 mg Ni kg⁻¹ levels, along with improving soil chemical properties and significantly increasing soil fertility. Further, the VCB application to Ni contaminated soils (100 and 200 mg Kg⁻¹) has significantly decreased soil-DTPA extractable Ni (59% and 44%), root and shoot Ni contents (56%, 65%, 56% and 53%), bioaccumulation factor (8% and 16%), respectively, compared with their corresponding Ni-only treatments. The VCB demonstrated a lower reduction in Ni translocation under Ni1 levels, whereas a significant reduction was found under Ni2 stress. The heatmap correlation and biplot PCA analysis confirmed that VC and VCB, particularly VCB, decreased soil and plant Ni, oxidative stress indicators, and metal accumulation factors and promoted growth, photosynthetic pigments and antioxidant variables through improved soil fertility compared to un-amended soil. This study provides a scientific basis and a practical solution for managing Ni-contaminated soils under diverse agroclimate conditions.

Aerobic granular sludge (AGS) technology is limited by slow granulation and structural instability. To overcome the shortcomings of existing carrier materials (e.g., activated carbon, sponge) regarding poor biocompatibility, inadequate pore connectivity, and surface chemical inertness, this study proposes a rapid AGS construction strategy based on a novel L-carrier (a renewable polymer material modified by alkali‑ultrasonic treatment to obtain hydrophilic, hierarchical porous, and high surface charge properties). Using sequencing batch reactors, the effects of the L-carrier on granulation progress, structural stability, and pollutant removal performance were systematically evaluated. Results showed that the L-carrier shortened the maturation time of the pre-formed composite granules to 5 days (defined as the time required to achieve stable granule morphology, settling velocity > 70 m h⁻¹,and TN removal rate increases), representing an 80% reduction compared to conventional self-aggregation. The obtained AGS exhibited a density of 1.062 g·(cm³)⁻¹, structural integrity > 0.95, and an average settling velocity of 70.9–74.2 m h⁻¹, which are significantly superior to reported activated-carbon-assisted AGS (settling velocity 55–65 m h⁻¹) and sponge-carrier systems (integrity ≤ 0.85). COD removal exceeded 90%, and total nitrogen removal reached 70–85%, which is significantly higher than typical values reported for conventional self-aggregated AGS (TN removal 50–70%) and sponge-carrier systems (55–70%), representing a 10–15% point improvement over similar carrier-assisted systems. High-throughput microbial analysis revealed that the L-carrier surface selectively enriched genera such as Thauera, Thermomonas, and Pseudoxanthomonas (total abundance > 25%), and their EPS (extracellular polymeric substances) production (especially polysaccharides in tightly bound EPS) was 2.3 times higher than that of carrier‑free systems. In summary, the L‑carrier not only serves as a physical scaffold but also enhances granule structural integrity and functional performance by modulating the interfacial micro‑ecology, providing a new approach for engineering application of AGS.

Graphical abstract

This study investigates the efficient removal of Malachite Green (MG) dye from aqueous solutions using a chemically treated peanut shell (Arachis hypogaea) agro-residue biosorbent (TPS). The biosorbent was prepared via sulfuric acid treatment and comprehensively characterized using N₂ adsorption–desorption, Thermogravimetry analysis (TGA), ultimate analysis, Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), Boehm titration, and pH of point of zero charge (pH_PZC). The specific surface area of TPS was S_BET = 14 m²/g, and pH_PZC was 3.2. The adsorption optimization was conducted using the Box-Behnken Design (BBD) approach and modeled using artificial intelligence via Artificial Neural Network (ANN) algorithms, including Levenberg–Marquardt (LM), Bayesian Regularization (BR), and Scaled Conjugate Gradient (SCG) models, where the BR model achieved the highest predictive accuracy (R² = 0.9876; RMSE = 0.58). Kinetic analysis revealed that the adsorption followed a pseudo-second-order model, while the equilibrium data were best described by the Freundlich isotherm, indicating multilayer adsorption on a heterogeneous surface. The Langmuir model estimated a maximum adsorption capacity (Qm) of 232 mg/g for TPS. Thermodynamic evaluation confirmed that the process was spontaneous and endothermic (ΔH° = 46.26 kJ/mol). The biosorbent retained strong adsorption performance after three regeneration cycles. Complementary Density Functional Theory (DFT) calculations provided molecular-level insights, revealing that MG adsorption onto TPS occurs predominantly through electrostatic attraction, hydrogen bonding, and π-π interactions between MG aromatic rings and lignin and hemicellulose fragments. Overall, the findings highlight peanut shells as a sustainable and low-cost precursor for producing efficient biosorbents for dye removal, contributing to food waste valorization and advancing circular bioeconomy strategies for sustainable wastewater treatment.

Graphical abstract

The alternative text for this image may have been generated using AI.

Efficient stabilization of heterogeneous lignocellulosic biomass remains a critical challenge in engineered biological waste treatment systems. This study presents a quantitatively evaluated two-stage biosystem integrating rotary drum composting (RDC) and vermicomposting for the valorization of Parthenium hysterophorus, with biochar applied as a process-level modifier. Unlike conventional composting studies, this work explicitly links thermophysical behaviour, degradation kinetics, and biological performance within a unified system framework. During the thermophilic RDC phase, biochar enhanced heat retention and moisture buffering, resulting in a higher peak temperature (60.8 °C) compared to the control (56.4 °C) and prolonged thermophilic conditions. Volatile solids (VS) reduction reached 54.6% within 15 days, indicating accelerated degradation kinetics. Subsequent vermicomposting further improved stabilization, with cumulative degradation of 42.01% and reduced respiration rates (1.6 mg g⁻¹ VS d⁻¹), confirming advanced maturity. Biochar significantly improved nutrient retention, increasing potassium (44.38 g kg⁻¹), calcium (10.22 g kg⁻¹), and phosphorus (13.05 mg kg⁻¹), while enhancing immobilization of trace metals such as Ag and Cr. Earthworm growth kinetics were also enhanced, with a maximum specific growth rate (SGR) of 0.063 day⁻¹. The findings demonstrate that biochar modifies system-level heat and mass transfer, microbial accessibility, and stabilization pathways, thereby improving process efficiency and product quality. This integrated biosystem provides a scalable engineering solution for converting invasive biomass into safe, nutrient-rich soil amendments, offering actionable insights for the design and optimization of sustainable waste-to-resource technologies under real-world operating conditions.

Graphical abstract

The alternative text for this image may have been generated using AI.

Heavy metal contamination poses a serious threat to agricultural sustainability, particularly in arid regions where soil and crop quality are easily compromised. This study evaluated the potential of indigenous plant growth-promoting rhizobacteria (PGPR) consortia, isolated from Peganum harmala L., to improve wheat (Triticum durum Desf.) growth and bioremediate lead-contaminated soils. Sixteen characterized strains, possessing both PGPR and heavy metal resistance traits were grouped into three consortia (SCA, SCB, and S(CA × CB)) derived from rhizosphere, endosphere, and mixed origins. Each consortium was inoculated separately onto wheat grown in soils containing 800 ppm lead (Pb). Results demonstrated significant improvements across treatments compared to the control: germination rates reached up to 100%; aerial fresh weight, total soluble sugars, phenolics, and flavonoids all increased markedly (up to 78.3, 61.0, 33.1, and 50.6%, respectively). Root system architecture, protein, and sugar contents also showed notable enhancements. These findings highlight the dual function of these indigenous consortia, as agents of both plant growth promotion and efficient bioremediation. Our work provides a practical, ecofriendly framework for restoring heavy metal-affected soils and optimizing crop productivity using tailored microbiological treatments.

Graphical abstract

The alternative text for this image may have been generated using AI.

Microbially induced phosphate mineralization (MIPP) is a promising strategy for immobilizing lead (Pb) in contaminated environments. This study aimed to determine whether cell viability and EPS are indispensable for Pb mineralization by Sinorhizobium sp. C10, a strain previously shown to form lead phosphate minerals. We compared live versus heat-inactivated cells, employed a mild sodium citrate method to strip EPS while preserving cell viability, and determined Pb removal efficiency, alkaline phosphatase (ALP) activity, inorganic phosphate (PO₄³⁻) release, and mineral phase composition. Live C10 cells removed up to 99.8% of Pb from solution (initial concentrations: 50 and 150 mg/L) within 26 h and formed crystalline Pb₅(PO₄)₃Cl. In contrast, heat-inactivated cells showed negligible ALP activity, failed to release Pi, and did not induce mineral formation. Despite retained cell viability, EPS stripping resulted in a marked reduction in Pb and P elemental signals on cell surfaces, along with diminished intensity of functional groups (e.g., P–O, C = O, –OH) critical for Pb binding. These findings demonstrate that both active cellular metabolism (specifically ALP-mediated Pi release) and intact EPS (providing essential functional groups) are indispensable for Pb biomineralization by Sinorhizobium sp. C10. Importantly, these two mechanisms are closely interlinked rather than independent: ALP-mediated metabolism generates phosphate ions that provide the chemical driving force for biomineralization, while EPS—itself a metabolic product—serves as a physical scaffold for Pb²⁺ adsorption and mineral nucleation. Together, active metabolism and intact EPS synergistically promote Pb₅(PO₄)₃Cl formation.

Graphical Abstract

The alternative text for this image may have been generated using AI.

Plastic pollution remains a major global environmental challenge due to the persistence and recalcitrance of synthetic polymers, particularly polyolefins such as polyethylene and polypropylene. Conventional management strategies, including landfilling, incineration, and chemical recycling, are energy-intensive and often fail to achieve complete degradation. Biological approaches offer a promising alternative, yet microbial systems alone are frequently limited by low degradation efficiency, incomplete mineralization, and challenges in scalability. In this context, insect–microbiome systems have emerged as integrated biological platforms in which host physiology and gut microbial communities interact to facilitate polymer transformation. This review synthesizes current knowledge on plastic degradation in insect larvae, with a focus on mechanistic insights into host–microbe interactions. Evidence suggests a multi-step process involving mechanical fragmentation, oxidative modification of polymer chains, microbial depolymerization, and metabolic processing of intermediates. However, the relative contributions of host-derived enzymes and gut microbiota, as well as the extent of true biodegradation versus partial transformation, remain incompletely resolved. Advances in multi-omics approaches have provided important insights into these systems by linking physicochemical changes in polymers to underlying molecular and metabolic processes. At the same time, these data are largely correlative, and direct experimental validation of specific enzymatic roles remains limited. Building on these insights, emerging enzyme engineering and synthetic biology strategies aim to replicate the coordinated, multi-step processes observed in insect systems for improved degradation efficiency. This review highlights insect–microbiome systems as valuable models for understanding complex biodegradation mechanisms and guiding the development of integrated, enzyme-based strategies for sustainable plastic waste management.

Graphical abstract

The alternative text for this image may have been generated using AI.

This study investigates the potential of the Microalgae-Microalgae (MM) cocultivated system as a sustainable phycoremediation strategy for the biodegradation and decolourization of the diazo dye congo red (CR). Decolourization was confirmed by UV–Vis spectrophotometry and FT-IR spectroscopy, with the cocultivated microalgal system achieving a maximum removal efficiency of 100% at a concentration below 20 mg L⁻¹, which gradually decreased with increasing contact time and reached 54% at an initial dye concentration of 100 mg L⁻¹. Beyond this concentration, the removal capacity plateaued. LC–MS analyses enabled the identification of key degradation intermediates, from which a plausible biocatalytic mechanism for CR breakdown was proposed. In addition, the biochemical response of the cocultivated system to CR exposure revealed a biphasic effect, indicating both adaptive metabolic regulation and stress-induced alterations. Overall, the findings demonstrate that the microalgal cocultivation system possesses significant decolourization capability under static conditions and offers a promising, low-energy approach for the remediation of dye-contaminated wastewater.