Biodegradation最新文献

Polycyclic Aromatic Hydrocarbons (PAHs) are hazardous organic pollutants known for their extreme toxic implications to living beings. Their potential carcinogenicity is the major problem related to hydrocarbon contamination. The development of efficient remedy for its removal remains a challenge. Microbial degradation represents an eco-sustainable strategy to detoxify these persistent pollutants. This study employs a novel and combined approach of metabolomic and genomic (whole genome sequencing) analyses to elucidate the mechanisms involved in the biodegradation of naphthalene, phenanthrene and fluorene by Priestia aryabhattai BMRS3B. Remarkably, BMRS3B sustains its growth and efficiently utilised naphthalene, phenanthrene and fluorene at concentrations up to 100 mgmL⁻¹, highlighting its high tolerance and utilisation efficiency. The strain achieved a maximum biodegradation of the selected PAHs—naphthalene, phenanthrene and fluorene and this was evidently supported with thin layer chromatography, UV spectroscopy along with Gas Chromatography Mass Spectrometry analysis. This revealed that the strain BMRS3B completely degraded naphthalene, phenanthrene and fluorene over 72–120 h, with phthalic acid esters, dibutyl phthalate, 1,2 dibenzenedicarboxylic, bis-3,5,5-trimethylhexylpthalate and didecan-2-yl phthalate identified as the principal intermediates. Moreover, the whole genomic analysis revealed genes encoding ring-cleaving dioxygenases, catechol 2, 3-dioxygenase, cytochromes P450 monooxygenases which are instrumental in bringing aromatic ring catabolism. Finally, a pathway for biodegradation of naphthalene, phenanthrene and fluorene by the selected isolate was proposed on the basis of metabolomic and genomic profiling. These findings place the strain P. aryabhattai BMRS3B as a promising candidate for the bioremediation of PAHs in the contaminated sites.

Microbial consortia are essential for the degradation of complex hydrocarbon mixtures in coastal environments, yet the functional basis of consortium performance rarely resolved at strain level. In this study, we employed a Plackett–Burman experimental design to rationally assemble and optimize a synthetic consortium for the degradation of medium-grade crude oil in a sand–seawater microcosm. Six strains were selected: Stutzerimonas stutzeri CBC1 and CBC2, S. balearica GOM11, Pseudomonas sp. CBC3, Halomonas litopenaei GOM23 and Enterobacter kobei GOM24. After 45 days, the consortium removed 15.72% of total hydrocarbons relative to the abiotic control, with markedly higher fraction-specific removal determined by GC–MS: 94.7% of phenanthrene, 63.1% and 41.0% of the C8-C27 and C18-C27 aliphatic fractions respectively. Comparative genomic analysis revealed a non-uniform distribution of catabolic functions consistent with metabolic complementary. Stutzerimonas and Pseudomonas strains carried ring-hydroxylating dioxygenases (nah/nag-like clusters) together alkane-degrading alcohol/aldehyde dehydrogenases (alkJ, alkH), whereas H. litopenaei GOM23 and E. kobei GOM24 encoded alternative long-chain alkane-hydroxylating systems (ladA). GOM24 further carried an expanded repertoire of ABC transporters and oxidative-stress genes (ahpC/ahpF), consistent with a role in substrate uptake and stress tolerance rather than in primary ring cleavage. Enzymatic assays supported this partitioning, catechol 1,2-dioxygenase activity was confined to the same four strain that encoded the gene and was highest in CBC1 and GOM11 (0.0472 and 0.0443 U·mg⁻¹ protein, respectively). No genome carried the classical alkB alkane-monooxygenase, pointing to alternative and partially redundant alkane-oxidation routes. By combining statistically guided assembly with comparative genomics and targeted enzyme assays, this work identifies a six-strain combination that removes more crude oil than the full eleven-isolate community and resolves how its catabolic functions are partitioned among strains.

Polyhydroxyalkanoates (PHAs) represent a family of biodegradable polymers that are precursors of bioplastics, offering a sustainable alternative to plastics derived from fossil fuels, within a circular economy framework. This study investigates the production of PHAs by the Cupriavidus necator bacterium, using as carbon sources synthetic media with volatile fatty acids (VFAs) and real effluents from dark fermentation (DFE) of seaweed wastes, which contain this type of acids. Experimental results indicate that, when acids are fermented singly, propionic acid yields a lower polymer quantity than acetic or butyric acids. However, when VFAs are supplied in mixtures, synergistic effects are observed. The kinetic models actually published fail to account for the increasing alkalinity of the medium during the VFA consumption, which frequently leads to biomass growth inhibition, and do not incorporate pH-dependent growth equations or consider the deleterious impact of alkaline conditions on the polymer stability. Thus, a novel kinetic model is proposed, based on the Monod equation, but integrating the inhibitory effects of pH in the biomass growth and the alkaline polymer degradation, with only nine fitting parameters. The new model allow for the robust prediction of the PHA production, the substrate consumption and the biomass growth, in the experimental conditions applied, which are typical of the PHA fermentations of DFE. The overall regression coefficient of theoretical curves (R²) is over 0.92, thus facilitating the designing and optimization of the industrial-scale processes.

Plastic pollution, resulting from the widespread use of plastics, their high production volumes, their ability to remain in the environment for long periods without decomposing, is one of the most significant global environmental problems, negatively impacting ecosystems, biodiversity, and human health. This study aimed to isolate marine fungi associated with microplastics, beach sand, and coastal seawater and evaluate their potential to modify low-density polyethylene (LDPE) under laboratory conditions. In total, 30 fungal isolates were obtained from beach sand, coastal seawater, and microplastic particles collected from the coastal area of Kuşadası, Aydın Province. The potential of the isolated fungi to modify LDPE was evaluated, and four fungal isolates were identified as potential PE-modifying candidates. The effects on LDPE were assessed using gravimetric weight loss measurements. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analyses were performed on the LDPE films after fungal treatment. After 45 days of incubation, the highest observed gravimetric weight loss was recorded for the following fungal species: Cladosporium sp. HBF380, Paradendryphiella sp. HBF381, Stemphylium sp. HBF384, and Didymella sp. HBF383, respectively. During the LDPE modification by Cladosporium sp. HBF380, which showed the highest degradation potential, FTIR and SEM were used to understand the changes on the LDPE film surface. LDPE modification was assessed using gravimetric weight-loss measurements, supported by FTIR and SEM observations. The isolate demonstrated the potential to modify LDPE under laboratory conditions. The study identifies marine fungal isolates associated with measurable physicochemical changes in LDPE and demonstrates their potential as candidates for further research on LDPE biodeterioration and biodegradation.

Shape-memory polymers and polymer composites can recover a programmed shape in response to external stimuli and have been investigated for applications including actuators, sensors, adaptive structures, and 4D printing. The majority of well-established systems use virgin petrochemical feedstocks, which has prompted interest in waste-derived and recycled alternatives. This review examines waste-derived and recycled shape-memory polymers and polymer composites prepared from plastic waste, agricultural residues, industrial by-products, e-waste, and waste cooking oil. Feedstocks are distinguished as waste-derived, recycled, upcycled, virgin bio-based, or hybrid systems. Reported processing routes, shape-memory performance, thermal and mechanical properties, cyclic durability, and application status are evaluated where data are available. Selected systems show high shape-fixity and shape-recovery values; however, comparisons remain constrained by differences in testing protocols, feedstock quality, and incomplete reporting of recovery stress, long-term aging, and repeated-cycle performance. The review also discusses contamination control, recyclability, reprocessability, biodegradability, regulatory considerations, and the need for standardized testing, life-cycle assessment, and techno-economic analysis. Waste-derived and recycled shape-memory polymers may support circular-material development, but their environmental and practical advantages require case-specific validation.

The extensive discharge of synthetic dyes from textile and pharmaceutical industries has created an urgent demand for eco-friendly and cost-effective purification technologies. In this study, a magnetic bio-based hybrid microgel adsorbent (SAFBCA) was fabricated by incorporating Fe₃O₄/biochar (FBC) and Aspergillus niger (A. niger) into a sodium alginate (SA) hydrogel matrix. Physicochemical characterization confirmed the formation of porous microspheres with a moderate specific surface area (8.22 m² g⁻¹) and sufficient magnetic responsiveness (9.31 emu g⁻¹) for facile recovery. The adsorbent achieved a Langmuir maximum adsorption capacity of 120.22 mg g⁻¹ for methylene blue (MB). Adsorption kinetics were best described by the pseudo-second-order model (R² = 0.997), and the equilibrium data followed the Langmuir isotherm (R² = 0.991). Thermodynamic analysis (ΔH° = −27.42 kJ mol⁻¹; ΔG° < 0 at 298–318 K) confirmed a spontaneous, exothermic adsorption process. Comparative studies revealed removal efficiencies of 65% (SA), 70% (SA/A. niger), 78% (SA/FBC), and 83% (SAFBCA), indicating supplementary contributions of both FBC and A. niger encapsulation to the adsorption process. The composite exhibited strong affinity for cationic pollutants, achieving removal efficiencies of 83% for MB and 90.3% for Cu²⁺, while showing lower removal for anionic Cr₂O₇²⁻ (56.6%) and Congo Red (21.5%). Mechanistic analyses revealed that MB uptake proceeds via electrostatic attraction, hydrogen bonding, and π–π interactions. This study presents a magnetically recoverable composite integrating renewable polysaccharides, waste-derived biochar, and fungal biomass, which retains ∼76% regeneration efficiency after five cycles and offers a sustainable platform for cationic dye remediation.

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Landfills are a major and, in several settings, growing source of methane, and many widely used operational- and inventory-scale estimates rely on first-order decay (FOD) models whose default parameterizations are largely underpinned by North American and European datasets. Whether these models transfer reliably to hot arid and hyper-arid systems—and specifically to the Arabian Gulf—remains unresolved. This critical review examines that question through a structured descriptive synthesis and an evidence-gap analysis for the six Gulf Cooperation Council (GCC) states. The provenance analysis shows that major frameworks represent aridity through broad climate or moisture categories, with limited direct calibration evidence from hot hyper-arid systems. The synthesis finds that the decay constant is climate-sensitive, with lower fitted values in drier settings; that realized methane yield can fall below nominal potential under persistent moisture limitation; that site-specific parameterization frequently departs materially from defaults; and that the direction of model–measurement disagreement is site-, method- and parameter-specific, so no systematic over- or under-estimation can be attributed to any framework. Screening the regional evidence, including geographic screening of a global satellite survey against GCC boundaries, identified no peer-reviewed site-level measured-versus-modeled landfill methane flux comparison for any GCC state in the present search; local, unindexed or grey studies beyond its reach cannot be excluded. Transferability to Gulf conditions is therefore conditional and not yet locally validated; the review converts this gap into a staged, uncertainty-explicit validation program to establish it by measurement.

Excessive alcohol intake triggers a series of systemic health hazards through the accumulation of acetaldehyde, a major carcinogen that poses a severe threat to human health. Here, a promising probiotic bacterial strain capable of biodegrading both ethanol and acetaldehyde was successfully isolated from healthy human feces and identified as Lactiplantibacillus plantarum YDL-01. In vitro assays demonstrated that an initial concentration of 5.0 g/L of ethanol or acetaldehyde could be completely biodegraded within 72 h or 16 h, respectively, by whole cells or cell-free extracts (CEs) of YDL-01, indicating that YDL-01 possesses a strong capacity for the biodegradation of both compounds. Whole-genome sequencing revealed the key genes responsible for alcohol metabolism in YDL-01, elucidating a complete catabolic pathway: ethanol is initially converted to acetaldehyde, catalyzed by alcohol dehydrogenase (ADH, EC 1.1.1.1), and acetaldehyde is further transformed into acetic acid via aldehyde dehydrogenase (ALDH, EC 1.2.1.10). In vitro safety assessments confirmed that YDL-01 exhibits no hemolytic activity and lacks amino acid decarboxylase activities, preliminarily verifying its biosafety, which is critical for the development of functional foods or biotherapeutic products for ethanol and acetaldehyde detoxification.

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The increasing environmental burden of biodegradable plastics such as poly (butylene adipate-co-terephthalate) (PBAT) necessitates a detailed understanding of their microbial degradation mechanisms. In this study, Gordonia sp. CN2K utilized PBAT as the sole carbon and energy source, with cell density increasing from 1.26 × 10⁸ to 6.26 × 10⁸ CFU mL⁻¹ over 90 days. PBAT degradation, determined by weight loss measurements, reached 52.8% within 45 days. ATR–FTIR analysis indicated ester bond cleavage and polymer backbone disruption, demonstrating chemical modifications in the PBAT polymer. SEM analysis revealed progressive surface erosion, confirming morphological deterioration during biodegradation. Metabolite profiling identified terephthalic acid (TPA), adipic acid (AA), and oligomeric intermediates, all of which supported bacterial growth as individual substrates. Notably, 1,4-butanediol was not detected in the medium, suggesting rapid uptake and metabolism. Enzyme assays revealed that esterase activity was induced exclusively in PBAT-grown cultures, with higher activity in the extracellular fraction, indicating surface-associated depolymerization. Intracellular enzyme analysis showed the presence of protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase, supporting the involvement of ortho-cleavage pathways in aromatic intermediate metabolism. Overall, the results demonstrate a coordinated degradation mechanism involving extracellular depolymerization and intracellular assimilation under substrate-dependent enzyme regulation. These findings highlight Gordonia sp. CN2K as a promising candidate for the biodegradation of PBAT and related copolyesters.

Emerging contaminants (ECs), including pharmaceuticals, antibiotics, personal care products, endocrine-disrupting compounds and persistent industrial chemicals, are increasingly detected in wastewater effluents because many are poorly removed by conventional treatment and may form biologically active transformation products. This review critically evaluates hybrid constructed wetlands (HCWs) as engineered biodegradation platforms for EC attenuation, with emphasis on microbial pathways, redox-zonation and substrate-mediated transformation. HCWs integrate vertical-flow, horizontal subsurface-flow and free-water surface units to create coupled aerobic, anoxic, anaerobic, rhizospheric and photic microenvironments. These zones support filtration and sorption, but importantly promote biodegradation, cometabolism, nitrification–denitrification, anaerobic ammonium-oxidation and sulfur-driven autotrophic-denitrification. Anammox bacteria, including Candidatus Brocadia, Candidatus Jettenia, and Candidatus Scalindua, contribute to low-carbon nitrogen removal by coupling ammonium oxidation with nitrite reduction. Sulfur-oxidizing denitrifiers Thiobacillus, Sulfurimonas and Sulfuritalea further stabilize anoxic electron-transfer conditions under carbon-limited wastewater. Although these communities do-not directly mineralize all ECs, they regulate redox gradients, biofilm activity and enzymatic environments that favour transformation of biodegradable and cometabolizable compounds. Conventional gravel and sand provide hydraulic support and show limited dissolved EC-removal, generally below 20–30%, whereas biochar, zeolite and LECA improve removal to 60–90% by enhancing sorption and microbial colonization. Functionalized media, including TiO₂-coated substrates, Fe/Mn materials and nano-zero-valent (nZVI) iron, can achieve 70–98% removal for selected recalcitrant ECs. Field systems commonly report 50–85% removal, whereas laboratory systems often exceed 90%, indicating a scale-up gap. This review highlights microbial responses to HCW, redox conditions, substrates, rhizosphere-interactions and wastewater characteristics, while identifying future needs in transformation-product tracking, and functional-gene monitoring for SDG 6-oriented wastewater treatment.