Biodegradation最新文献

Heavy metals in aquatic environments pose significant environmental and human health risks, highlighting the urgent need for innovative remediation strategies. This study explores the role of bacterial extracellular polymeric substances as active binding surfaces for copper, in planktonic cells and biofilm-based adsorption systems. Serratia plymuthica strain As3-5a(5) achieved 92% Cu(II) biosorption (from an initial concentration of 3.14 mM) within 4 min in a non-proliferating planktonic cell system, and 98% biosorption in a biofilm-based system on sintered glass. Maximum metal biosorption was achieved by late stationary phase grown cells (72 h), likely due to an increased protein fraction in the tightly bound extracellular polymeric substances. When in the presence of real electroplating wastewater containing 40 mM Cu(II) at pH 1.9, planktonic cell system (10¹¹ cells mL⁻¹) achieved 97% Cu(II) biosorption. These results highlight the strong potential of Serratia plymuthica strain As3-5a(5) for developing efficient biological systems for heavy metal removal from industrial wastewater. Furthermore, this work provides valuable insights into sustainable biotechnological approaches for copper remediation, with potential applications in catalytic processes and metal recovery within a circular economy framework. Future studies should involve synthetic biology approach to improve copper sequestration and to investigate the scalability of these systems to higher technology readiness levels under real industrial wastewater conditions.

Oily refinery sludge is rich in aliphatic and aromatic hydrocarbons, salts, and metals, complicating disposal in coastal settings. Indigenous halotolerant bacteria (Bacillus, Pseudomonas, Alcanivorax) and fungi (Aspergillus, Penicillium) were isolated from Skikda (RA1K, Algeria) sludge and evaluated as monocultures and mixed consortia in saline minimal medium (20 g/L NaCl) containing 5% or 20% (v/v) crude oil. Over 28 days, mixed consortia achieved the highest total petroleum hydrocarbon (TPH) removal (82 ± 3% at 5% oil and 65 ± 4% at 20% oil), exceeding the performance of the best monocultures. GC–MS analysis showed near-complete loss of low-molecular-weight n-alkanes (C₇–C₁₂) and partial removal of high-molecular-weight fractions (C₂₅–C₃₀); BTEX compounds decreased by 80–90% at 5% oil and light polycyclic aromatic hydrocarbons by 40–65%. Elevated emulsification indices (EI₂₄ up to 55%) and strong biomass–TPH correlations (R² = 0.91) indicate biosurfactant-mediated mass transfer and interkingdom complementarity. Despite reduced efficiency at higher oil loading, indigenous consortia maintained substantial degradation under saline conditions, highlighting their promise for refinery sludge bioremediation in Mediterranean coastal environments.

Nickel is a toxic and carcinogenic metal, and its existence in water bodies is a major hazard to human and environmental health. Sludge production, high operating costs, and low efficiency at low metal concentrations are some of the shortcomings of conventional nickel elimination treatment strategies like chemical precipitation, ion exchange, and membrane filtration. Nanotechnology effectively removed nickel ions from water. The use of nanotechnology offers an effective route toward the removal of nickel ions (Ni²⁺) from water, and this paper reviews recent advances in nanoadsorbents that are designed for this purpose. Through experimental adsorption studies, surface-functionalization strategies, and isotherm/kinetic modelling, the review highlights that the best carbon-based nanomaterials, metal oxides, biopolymer nanocomposites, and hybrid structures all show better adsorption capacities and faster kinetics compared to bulk materials. Ni²⁺ selectivity is significantly enhanced by functional groups such as amidoxime, carboxyl, thiol, and amine; magnetic nanoadsorbents allow easy separation with stable multi-cycle reuse. Adsorption efficiency is strongly modulated by pH, temperature, contact time, initial metal concentration, and competitive ions, dominated by mechanisms including electrostatic attraction, surface complexation, ion exchange, and chelation. Major challenges lie in limitations in scale-up, production cost, and uncertainties on environmental impacts. Greener synthesis, improvement of regeneration efficiency, and comprehensive toxicity testing are encouraged by the review to promote practical and sustainable applications.

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Bio-based and biodegradable polymer blends are promising alternatives to conventional plastics, yet their environmental fate remains poorly understood. Here, we investigated the enzymatic and environmental degradation of natural rubber (NR) blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) using recombinant enzymes produced in Escherichia coli and Komagataella phaffii. Three PHB depolymerases from Pseudomonas lemoignei (PlDP), Acidovorax sp TP4 (AsDP), and Ralstonia pickettii (RpDP) were isolated and analyzed for thermal and pH stability. All depolymerases efficiently degraded the PHB/PHBV fraction in films and blends, whereas NR was largely resistant to degradation. To enhance rubber degradation, the latex-clearing protein from Streptomyces sp. K30 (Lcp_Ssp) was produced recombinantly and applied. It showed significant activity on NR substrates, including pretreated PHB–NR blends, demonstrating a synergistic two-step enzymatic process. Scanning electron microscopy and weight-loss assays confirmed selective PHB/PHBV degradation. Separate seawater pH–Stat degradation experiments under environmentally relevant conditions with four hydrolytic enzymes (protease, lipase, esterase, and PlDP), showed highest activity of PlDP on PHB/PHBV–NR blends. Additionally, incubation in estuarine mud revealed progressive surface erosion and pore formation, particularly in PHB-rich blends, highlighting the role of PHB/PHBV in facilitating overall biodegradation. This comprehensive assessment of enzymatic and environmental degradation processes of PHB/PHBV–NR composites provides information to design fully bio-based, degradable polymer materials for sustainable applications.

Drought stress is a major abiotic constraint limiting crop productivity and ecosystem stability in arid and semi-arid regions. The use of stress-adapted plant growth–promoting rhizobacteria (PGPR) represents a sustainable strategy to enhance crop resilience while maintaining soil ecological function. This study characterized a desert-adapted, halotolerant Exiguobacterium sp. C-20, isolated from the rhizosphere of Panicum antidotale in the Cholistan Desert (Pakistan), for its plant growth–promoting traits and its ability to mitigate drought stress under controlled conditions. The strain exhibited strong phosphate-solubilizing activity, produced indole-3-acetic acid (IAA), and generated ammonia in vitro, confirming its functional potential as a PGPR. In greenhouse experiments, seed and soil inoculation of maize (Zea mays L.) hybrids (G-3 and G-7) exposed to drought (40% field capacity) significantly improved photosynthetic performance, stomatal conductance, chlorophyll stability (SPAD values), biomass accumulation, and tissue moisture content compared with non-inoculated controls. These improvements reflect enhanced plant physiological performance under water deficit rather than speculative mechanisms. Overall, the findings identify Exiguobacterium sp. C-20 as a promising microbial resource for developing eco-sustainable bioinoculants to improve drought tolerance and productivity in dryland agroecosystems.

This study aimed to isolate, identify, and characterize individual bacterial isolates obtained from the activated sludge of the biological treatment basin at the new industrial wastewater treatment plant of the Skikda refinery (ETP II, Algeria). Seven distinct bacterial strains were isolated and identified as Bacillus licheniformis, Bacillus cereus, Bacillus aerius, Pseudomonas mucidolens, Pseudomonas stutzeri, Microbacterium oryzae, and Micrococcus aloeverae. Identification was based on morphological and biochemical characterization (API galleries) and confirmed by sequencing of the 16S rRNA gene.

The biodegradation potential of these isolates was evaluated in Bushnell–Haas medium enriched with 2% (v/v) crude oil as the sole carbon source. The effects of temperature, pH, and salinity on bacterial growth and oil tolerance were investigated to assess optimal environmental conditions for hydrocarbon degradation. The results revealed maximum bacterial growth and crude oil degradation efficiency between 30–35°C, pH 6–9, and 4–6% NaCl. Among the isolates, Bacillus licheniformis, Bacillus cereus, and Pseudomonas stutzeri exhibited superior performance under extreme physicochemical conditions and demonstrated high tolerance to crude oil concentrations up to 25% (v/v).

These findings highlight the remarkable adaptability of indigenous hydrocarbon-degrading bacteria and their potential application in optimizing biological treatment processes and bioremediating oil-contaminated industrial effluents.

The widespread accumulation of macro- and microplastics in terrestrial and marine environments has emerged as a pressing global challenge due to their persistence, ecotoxicological effects, and disruption of biogeochemical processes. Conventional plastic waste management strategies remain inadequate, thereby driving interest in biodegradation as a sustainable alternative. This review critically evaluates microbial, enzymatic, and physicochemical mechanisms involved in the degradation of commonly used polymers, including polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS). Microorganisms such as Pseudomonas, Ideonella, and Aspergillus spp. have demonstrated promising degradation potential, mediated by enzymes such as PETase, cutinase, and laccase. The ecological implications of plastic fragmentation and its degradation byproducts on marine ecosystems, biodiversity, food webs, and human health are also highlighted, with particular attention to major plastic-emitting regions such as the Philippines, India, and China. Finally, the review discusses current limitations and future directions, including genetic engineering of plastic degraders, integration of biodegradation with circular bioeconomy frameworks, and the design of inherently biodegradable polymers. Addressing plastic pollution effectively will require an interdisciplinary strategy that integrates microbiology, materials science, and environmental policy.

Industrial wastewater often contains high concentrations of Cr(VI), posing serious environmental and health threats. This study introduces a novel approach to enhancing the adsorption performance of lignocellulosic materials through thermal chemical modification of water hyacinth using dilute H₂SO₄ under mild (low-temperature) conditions, and then a microbial treatment step by a cellulolytic bacterium strain. The effects of modification time (0–50 h), acid volume/material ratio (3–11 mL/g), temperature (25–60 °C), and acid concentration (0.5–3% v/v) were systematically evaluated using a one-factor-at-a-time (OFAT) method and further optimized via Box–Behnken Design (BBD) coupled with response surface methodology (RSM). Under the optimal conditions (30 h, 5.5 mL/g, 45 °C, and 1.5% v/v H₂SO₄), the treated biomass achieved a maximum Cr(VI) adsorption capacity of 3.22 mg/g. Characterization using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analysis confirmed that the mild acid treatment effectively reduced cellulose crystallinity, and introduced abundant C = O and O–H functional groups, while the surface area (1.86 m²/g) remained unchanged. The zero point of charge (pH_pzc) of treated water hyacinth (TWH) was determined to be 5. Adsorption followed the Langmuir isotherm (R² = 0.972) and pseudo-second-order kinetic model (R² = 0.9982), involving both intra- and extra-particle diffusion. Furthermore, the results revealed that microbial treatment with Alcaligenes sp. KHM19 for 6 days achieved a Cr(VI) removal efficiency of 95.42% and an adsorption capacity of 3.85 mg/g, which was approximately 1.2 times higher than that obtained by thermal-acidic modification alone. This integrated method, combining biological treatment with thermal chemical modification, represents a novel and sustainable strategy for efficient Cr(VI) removal from industrial wastewater.

The leather industry of West Bengal continuously discharges chromium-laden effluents, with hexavalent chromium [Cr(VI)] being particularly persistent and toxic. Hexavalent chromium released from tannery effluents poses serious environmental and public health hazards due to its high mobility, solubility, and carcinogenicity. Biosorption offers a sustainable and cost-effective alternative to conventional physicochemical remediation methods. In this study, the biosorption potential of Bacillus cereus F4810/72, a strain previously isolated from tannery wastewater, was systematically evaluated for Cr(VI) removal under varying physicochemical conditions. Batch experiments were conducted to investigate the influence of initial metal concentration (10–1000 µg/mL), contact time (10–100 min), pH (1–9), biomass concentration (1–4 g/L), temperature (10–60 °C), and agitation speed (10–120 rpm) on biosorption efficiency. Maximum Cr(VI) removal (approximately 79–80%) was achieved under optimized conditions: 250 µg/mL initial Cr(VI), 4 g/L biomass, pH 3, 50 °C, 70 min contact time, and 80 rpm agitation. Langmuir and Freundlich isotherm models were applied to elucidate adsorption behavior. Nonlinear Langmuir modeling indicated monolayer adsorption with a maximum capacity (Q_max) of 28.57 mg/g, whereas the Freundlich model (R² = 0.98) suggested adsorption onto a heterogeneous surface. Regeneration studies showed that 2 M HCl and a combined HNO₃–ascorbic acid eluent exhibited superior desorption efficiencies, maintaining high uptake–release performance across three cycles. Overall, B. cereus F4810/72 demonstrates strong Cr(VI) biosorption and regeneration potential, highlighting its viability as a low-cost, eco-friendly biosorbent for chromium-contaminated industrial wastewater systems.

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Used engine oil is considered a major environmental concern due to difficulty in disposal or reuse. Using enrichment method, nine bacterial strains were isolated from the oil contaminated sites in Abbottabad. The NMD strain was considered the best biosurfactant producing strain, having the highest emulsification index and cell hydrophobicity up to 72% and 67% respectively. Based on morphology and 16S rRNA sequence analysis, the isolate was identified as Enterobacter hormaechei strain NMD. The effect of various factors which may influence the biodegradation rate including pH, incubation temperature and oil concentration were evaluated by response surface methodology with Box-Behnken design. The analysis of variance (ANOVA) indicated that regression coefficient (R²) is 0.99 with P-value 0.0325 with best fitted second-order quadratic regression model for used engine oil degradation. The F value of model is 338.13 with P-value < 0.0001 showed that the applied model is statistically significant and the optimal parameters i.e., temperature, pH and inoculum size, were observed to have significant effect on engine oil degradation efficiency. The optimum parameters temperature, pH and engine oil concentration were found to be 32.5℃, 6.5, and 4% (v/v) respectively. Under the optimized conditions, the degradation efficiency of used engine oil is observed 80%, which closely matched with the predicted values. The Monod kinetic equation is used to determine the growth rate of isolated strain utilizing used engine oil as sole carbon source with the highest rate of μmax (h-1) = 0.112, with Ks 9.5, and μmax/ Ks is 0.011 mg/L/h. The engine oil degradation was confirmed by GC/MS analysis, and its metabolites were also identified providing comprehensive insights into the breakdown products and degradation efficiency. This is the first report on the growth kinetics of these biosurfactants NMD on used engine oil, with these parameters helping to assess the isolated bacterial strain’s capability to degrade the pollutant effectively and guiding the development of more efficient bioremediation strategies. The future study should elucidate detail metabolomic study, optimization study at larger scale bioremediation process and enhancement of bacterial degradation efficiency through immobilization and use of consortium approaches.