Biodegradation最新文献

Synthetic azo dyes, extensively utilized in textile and allied industries, are a persistent source of environmental contamination due to their chemical stability, xenobiotic nature, and resistance to conventional wastewater treatment. In this study, Lactobacillus casei immobilized on porous clay substrates was evaluated for the biodegradation of six reactive dyes: Reactive Red 198, Reactive Violet 5, Reactive Yellow 3, Reactive Orange 5, Reactive Navy Blue 4, and Reactive Black 5 sourced from textile effluents. Decolorization assays demonstrated efficient removal across concentrations of 250–1000 mg/L, with maximum degradation observed at pH 7, 37 °C, and 72 h under static conditions, achieving removal efficiencies of 90.17% (RR198), 92.24% (RV5), 92.18% (RY3), 94.04% (RO5), 95.66% (RNB4), and 92.18% (RB5). Response Surface Methodology (RSM) using the Box–Behnken design facilitated optimization of operational parameters, and statistical analyses confirmed model adequacy, with predicted and experimental decolorization values in close agreement. By accounting for interactive effects among variables, RSM achieved superior degradation efficiency compared to the single-factor OFAT approach. FTIR analysis revealed the disappearance and shifting of characteristic –N = N– (azo), –OH, and –NH peaks, indicating cleavage and modification of the dye’s functional structure. Complementary HPLC profiling showed the emergence of new peaks with altered retention times, confirming the formation of low-molecular-weight metabolites and providing clear evidence of dye biodegradation. Phytotoxicity assays using Vigna radiata demonstrated that degraded metabolites exhibited minimal toxicity, with plumule and radicle growth comparable to the control. The germination percentage in untreated dye controls was only 20–40%, whereas the degraded dye–treated samples showed significantly higher germination rates of 80–95%. These findings highlight L. casei immobilized on porous clay as a cost-effective, environmentally sustainable, and mechanistically robust strategy for the remediation of azo dye-contaminated wastewater, with potential for scalable industrial application.

Wheat (Triticum aestivum L.), a vital global staple, suffers substantial yield losses under concurrent salinity and drought stress—two major constraints to sustainable agriculture and food security. This study, conducted at The Islamia University of Bahawalpur, Pakistan, evaluated the individual and combined effects of gibberellic acid (GA₃) and biochar (BC) on wheat performance under salinity (2.43 and 5.11 dS m⁻¹) and drought stress (35% field capacity). A completely randomized design with sixteen treatment combinations was employed in triplicate. Compared with the stressed control (no amendments), the combined application of GA₃ and BC significantly improved germination rate by 8.8% under salinity stress and by 8% under drought stress. Shoot and root lengths under salinity stress increased by 43% and 41%, respectively, and under drought stress by 34% and 30%. Shoot and root fresh weights were enhanced under salinity by 23% and 14%, respectively, and under drought stress by 12% and 3.3%. Relative water content increased under salinity from 52.49% to 61.26% and under drought from 62.54% to 66.96%. Total chlorophyll, chlorophyll a, chlorophyll b, and carotenoid contents were also elevated, with carotenoids increasing by 39% under salinity and 85% under drought, reflecting improved photosynthetic efficiency and photoprotection. These findings demonstrate a synergistic effect of GA₃ and BC in enhancing wheat tolerance to salinity and drought stress through improved water retention, pigment stability, and early seedling vigor. The integration of these eco-friendly amendments offers a promising, sustainable strategy to improve wheat resilience and productivity in stress-prone environments, contributing to long-term food security.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants widely found in the environment due to natural and anthropogenic sources, including fossil fuel combustion, industrial emissions, and vehicle exhaust. These hydrophobic compounds are resistant to degradation, bioaccumulate in ecosystems/water, and pose significant environmental and health risks, including carcinogenesis and respiratory disorders. Conventional remediation methods, such as chemical and physical treatments, are often costly, energy-intensive, and environmentally disruptive, prompting the search for sustainable alternatives. Microbial bioremediation has emerged as an effective solution, leveraging the natural ability of microorganisms to degrade PAHs through enzymatic pathways. This approach offers an eco-friendly, cost-effective method for PAHs removal from contaminated sites. This review focuses on the biodegradation of various PAHs, such as naphthalene, phenanthrene, anthracene, and pyrene, by bacteria including Pseudomonas, Mycobacterium, Rhodococcus, and marine species from the Novosphingobium genus. These microbes use dioxygenase enzymes to initiate the breakdown of PAHs into less toxic intermediates. Additionally, the review explores the role of biosurfactants and biofilms in enhancing the bioavailability of PAHs, promoting more efficient degradation. This paper also discusses the advantages of microbial consortia, where multiple species collaborate to degrade a broader range of PAHs. Recent advancements in genetic engineering, synthetic biology, and nanotechnology are highlighted as promising tools to further enhance microbial degradation efficiency. The microbial bioremediation represents a sustainable solution to PAHs contamination, complementing traditional methods and offering significant potential for environmental restoration and human health improvement.

Antibiotic contamination has emerged as a critical environmental challenge due to its persistence, difficulty in removal, and adverse impacts, including gene dissemination, resistance, and ecosystem disruption. Despite their clinical and agricultural benefits, the release of antibiotics into the environment is poorly regulated, leading to growing ecological and public health concerns. Conventional physicochemical methods, including advanced oxidation processes, activated carbon adsorption, and membrane filtration, are highly effective for antibiotic removal but are constrained by high costs associated with energy use, chemical inputs, and membrane replacement. Additionally, techniques such as Fenton reactions (using iron hydroxides with antibiotic residues), coagulation flocculation (binding metal hydroxides to antibiotics), and electrocoagulation (producing electrode corrosion sludge) generate toxic sludge, complicating its disposal. More sustainable approaches, such as bioremediation, biochar-assisted systems, anaerobic and aerobic digestion, biological aerated filters, and microbial fuel cells, demonstrate cost-effectiveness and minimal sludge production. However, both physico-chemical and biological methods still face limitations, emphasising the need for integrated solutions. Hybrid technologies that combine conventional and biological techniques, such as biochar-based bioreactors coupled with membrane separation or advanced oxidation, offer a promising approach for effective remediation. Emerging strategies also highlight the role of novel adsorbent materials (e.g., activated carbon, sawdust) and the application of machine learning in optimising antibiotic waste treatment. Future strategies require coordinated action across healthcare, agriculture, and the pharmaceutical sector, alongside robust risk assessment frameworks that consider both human and environmental health. This review examines current bioremediation strategies, hybrid technologies, and policy measures, underscoring the importance of integrated and sustainable approaches to address antibiotic contamination and resistance genes.

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Triiodinated aromatic compounds used as iodinated contrast media in medical imaging are poorly biodegradable. Reductive dehalogenation enhances biotransformation, but the specific influence of iodination degree on biodegradation remains unclear. This study investigated the biodegradation of twelve model substances: iopromide and diatrizoate (both iodinated contrast media), 5-amino-2,4,6-triiodoisophthalic acid (ATIA, a precursor and transformation product), and their diiodinated, monoiodinated, and deiodinated derivatives. Biodegradation kinetics were assessed in Zahn-Wellens tests and nitrate-reducing aquifer material–water batch tests. DT₅₀ values were calculated to compare degradation rates. Transformation pathways were reconstructed based on literature data and detected transformation products, and evaluated for dependencies on iodination degree. In Zahn-Wellens tests, the iopromide derivatives degraded rapidly (DT₅₀: 0.7–1.2 d) regardless of iodination degree. In contrast, degradation of the diatrizoate derivatives (DT₅₀: 0.9–65 d) and the ATIA derivatives (DT₅₀: 0.3–44 d) was strongly influenced by iodine number and position. For iopromide, transformation pathways were consistent across derivatives and included several novel transformation products beyond the previously assumed final product DDPI. In nitrate-reducing aquifer suspensions, aerobic pathways also occurred for the iopromide derivatives (DT₅₀: 38.7–42.3 d). In contrast, only the monoiodinated and deiodinated diatrizoate were transformed (DT₅₀: 5.6–8.2 d). Mineralization of the ATIA derivatives, measured via dissolved organic carbon, was significantly enhanced for the monoiodinated and deiodinated compound. The findings underline the importance of iodination degree for biotransformation and mineralization. This is particularly relevant for bank filtration, where (partial) deiodination to iodinated aromatics occurs before these compounds enter aerobic drinking water treatment.

This investigation evaluates the performance of a sequencing batch moving bed biofilm reactor (SB-MBBR) employing Ceramic Rings and K1 biofilters as biofilm carriers for the removal of phenol and chemical oxygen demand (COD) from synthetic landfill leachate. The SB-MBBR integrates the operational principles of sequencing batch reactors (SBR) and moving bed biofilm reactors (MBBR), operating under aerobic conditions to optimize critical parameters, including contact time, carrier surface area, and filling ratio. The biofilm carriers provided distinct surface areas for microbial colonization, significantly influencing microbial activity and pollutant degradation kinetics. Experimental results demonstrated that phenol and COD removal efficiencies exhibited a logarithmic relationship with increased contact time and carrier surface area. Under optimized conditions, the K1 biofilter achieved maximum removal efficiencies of 94.5% for phenol and 88.7% for COD. Ceramic Rings also exhibited high pollutant removal efficiency, with stable operation at moderate filling ratios. However, excessive carrier concentrations resulted in reduced mixing efficiency, underscoring the necessity of optimizing carrier loading. The study further examined the influence of initial phenol and COD concentrations on biodegradation performance. Elevated initial concentrations led to reduced removal rates due to substrate inhibition, emphasizing the importance of controlled substrate loading. Predictive models, including Random Forest and multiple linear regression, were developed to correlate operational parameters with removal efficiencies, yielding high predictive accuracy. These findings establish the SB-MBBR as a robust and adaptable technology for the treatment of high-strength landfill leachate, providing valuable insights into carrier selection and system optimization for enhanced pollutant removal.

This study investigates the novel application of biochar derived from Bixa orellana fruit shell (BOFS), an underutilized agricultural waste, to enhance the performance of microbial fuel cells (MFCs) for textile dye wastewater treatment and energy generation. Four different BOFS biochar doses (0.5, 1, 1.5, and 2 g) were examined, and the optimal dose of 1.5 g achieved a maximum power density of 300 mW/m²—representing a 24-fold enhancement over the control—along with 88.39% COD removal, 81.6% decolorization efficiency, and 84.4% TDS reduction. Structural and compositional analyses using SEM, EDX, FTIR, and UV–Vis spectrophotometry confirmed improved biofilm formation, efficient pollutant adsorption, and azo bond degradation, indicating synergistic enhancement of both bioelectrochemical and treatment performance. The study uniquely demonstrates the dual functionality of BOFS biochar as a low-cost, conductive, and sustainable additive that promotes microbial adhesion and electron transfer while valorizing agricultural waste. These findings position BOFS biochar as an innovative, eco-friendly bioelectrochemical enhancer for scalable applications in wastewater remediation and renewable energy generation.

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Environmental imbalances caused by pollution and climate change has led to extreme erratic change in weather patterns and widespread ecosystem distress. In order to mitigate these imbalances, numerous sustainable methods have been adopted, among which microbial remediation strategy mediated through microbial enzymes holds significant promise. One such class of enzyme- laccase (EC 1.10.3.2) is known multicopper oxidase enzymes, naturally reported from bacteria, fungi, insects, plants can catalyze the oxidation of a wide range of phenolic and non-phenolic substrates by reducing molecular oxygen to water which imparts antioxidant properties to the enzyme, making it valuable in combating oxidative stress—a condition increasingly prevalent due to climate-induced environmental distress. The enzyme is also known for its multifarious applications of laccase, including heavy metal degradation and detoxification, decolorization of dyes, degradation of plastics, and optimization of food stability. The present review focuses on emphasising the role of laccase in improving the environmental health by balancing the oxidative status and remediation the pollutants.

Agricultural mulch films (AMFs) enhance crop productivity by controlling soil temperature and moisture and suppressing weed growth. Conventional AMFs made from polyethylene (PE) pose disposal challenges and contribute to long-term plastic pollution. Biodegradable mulch films (BMFs) offer a promising alternative, but their degradation in soil remains slow and inconsistent. This study employed a culture-enrichment approach to isolate soil bacteria (i.e., Pseudomonas guariconensis and Achromobacter denitrificans) capable of accelerating BMF biodegradation. Bioaugmentation with P. guariconensis enhanced CO₂ evolution in soil, with 48% and 36% carbon mineralization for two commercial BMFs (i.e., Bio360 and EcoVio), compared to 17% and 6.2% in non-inoculated soils. These findings demonstrate that targeted bacterial enrichment can accelerate BMF degradation, highlighting the potential for bioaugmentation to mitigate plastic accumulation in agricultural soils.

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Biodegradation has been the most sought method for degradation of various xenobiotic contamination including crude oil contamination, but it has shown limited efficiency due to the hydrophobic property of the crude oil. In order to overcome this drawback, microbial species along with minerals having ability to adsorb oil onto its surface can be used to increase its availability. In this study, an attempt to increase the bioavailability of the crude oil by adsorption by addition of the oil degrading microorganisms to the ex-situ system was performed to determine efficiency. Firstly, the study involved the synthesis and characterization of the nanoparticles obtained from calcium carbonate shells of Semibalanus balanoides (Acorn Barnacles), and the isolation of Paenibacillus dentritiformis (a Gram-positive bacterium) for production of oil mineral aggregate (OMA). The synthesized calcite nanoparticles were characterized using XRD, FTIR, ZETA Sizer and Potential, HR- SEM, EDS, HR-TEM. The structural analysis showed that the OMA was larger in size compared to cuboidal nanoparticles at 500 nm. Further, the degradation potential of the OMA was comparatively more at 88% and the biodegradation potential of P. dentritiformis was 67% when compared to the control. These results suggested that the change in the surface morphology of the nanoparticles by the formation of OMA reduced the hydrophobicity of the crude oil, thereby increasing its bioavailability for enhanced degradation.

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