Biodegradation最新文献

This study evaluates the bioremediation potential of eight indigenous fungal strains isolated from chromium- and zinc-contaminated soils of the Korangi Industrial Estate, Karachi, Pakistan. The site, a major industrial hub hosting tanneries, metal plating, and chemical plants, has long suffered from heavy metal pollution due to untreated effluent discharge. To assess the remediation efficiency of these native fungi, bioleaching experiments were conducted under controlled ex-situ conditions using five nutrient media—Potato Dextrose Broth (PDB), Sabouraud Dextrose Broth (SDB), Yeast Peptone Dextrose (YPD), Yeast Peptone Glucose (YPG), and Czapek Dox Broth (CDB). Each 250 mL flask contained 100 mL of sterilized medium inoculated with 1 mL of spore suspension (≈10⁸ spores mL⁻¹) and 1 g of contaminated soil. Incubation was maintained at 32 °C, 150 rpm, and pH 6.5 for 144 h, with uninoculated controls to monitor abiotic metal release. Residual metal concentrations in the leachates were quantified by Atomic Absorption Spectroscopy (AAS). Uptake capacity (mg g⁻¹) was calculated based on the dry fungal biomass obtained after centrifugation and oven drying at 80 °C. Statistical analysis was performed using two-way ANOVA followed by Tukey’s post-hoc test (p < 0.05) to evaluate the effects of medium composition and fungal strain on bioleaching efficiency. Among all isolates, Aspergillus niger (K8) achieved the highest chromium removal (98.6%) with a maximum uptake of 0.3178 mg g⁻¹ in SDB, while Penicillium notatum (K1) exhibited superior zinc removal (94.5%) and uptake of 0.32 mg g⁻¹ in CDB. FTIR analysis confirmed that hydroxyl, amine, alkene, nitro, and tertiary alcohol functional groups on the fungal cell wall were actively involved in metal binding. SEM imaging further revealed hyphal curling and surface deformation after metal exposure, reflecting structural adaptation under stress. These findings demonstrate that indigenous fungal species are highly effective for the ex-situ removal of Cr and Zn from polluted soils. While laboratory-scale results are promising, future field-level applications must address pH sensitivity, fungal survival in native soils, and competition with existing microbiota. Nonetheless, A. niger (K8) and P. notatum (K1) represent potent, eco-friendly candidates for sustainable bioremediation and restoration of metal-contaminated industrial sites in Pakistan.

The growing contamination of terrestrial systems by heavy metals and organic pollutants is driving research towards sustainable and environmentally responsible remediation technologies. Engineered biochar, developed through physical, chemical, or biological modification, has recently emerged as an attractive, multifunctional platform to facilitate more effective soil remediation. Its customized surface characteristics, large sorption capacity, and stability in the environment provide the potential to both immobilize contaminants and facilitate positive exchanges with either native or inoculated microbial communities. Biochar–microbe systems not only enhance the bioavailability of contaminants for biodegradation and immobilization but also improve soil health by enriching microbial diversity, nutrient cycling, and carbon dynamics. The novelty of this review lies in its integrative evaluation of engineered biochar–microbe interactions as a climate-resilient remediation strategy, highlighting how synergistic mechanisms of adsorption, redox transformation, and biodegradation can outperform conventional remediation approaches. The need for this review arises from the lack of comprehensive assessments that integrate technological advancements (e.g., nanoparticle doping, surface oxidation, and microbial augmentation) with ecological perspectives, cost-effectiveness, and field-scale validation. We also discuss practical case studies that confirm the real-world efficacy of biochar–microbe systems and emphasize their dual role in soil detoxification and climate change mitigation through carbon sequestration and greenhouse gas reduction. This forward-looking synthesis provides a well-defined framework for advancing biochar–microbe systems as next-generation solutions for sustainable remediation.

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Several options are available to encourage the degradation of food waste, but microbial approaches have attracted attention due to their efficiency and sustainability. Among various microorganisms, Bacillus species are notable for their ability to degrade starch, protein, and cellulose, making them ideal candidates for food-waste management. While methods of isolating and measuring the activity of individual Bacillus enzymes are well established, few attempts have been made to evaluate enzyme activity directly in Bacillus cultures without purification. In this study, we screened various methods of measuring enzyme activity and developed a simplified approach using agar plate assays and direct measurement of reaction products in liquid cultures without purification. Bacillus strains were isolated from traditional Korean fermented foods and their ability to degrade food waste was evaluated. Among 56 isolates, six superior strains were identified and combined to form a composite culture. This composite exhibited significantly higher enzymatic activity and food-waste degradation efficiency compared with commercial microbial preparations, achieving superior volume-reduction rates under industrial conditions. This study highlights the feasibility of measuring enzymatic activity directly in microbial cultures and identifies a promising composite culture for sustainable food-waste management. Our findings demonstrate the feasibility of using simplified enzyme assays for microbial screening and food-waste degradation applications.

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Global scientific literature has extensively documented the overuse of antibiotics, the proliferation of antibiotic-resistant bacteria, and the toxic effects on aquatic fauna from hospital wastewater exposure, highlighting the need for effective antibiotics treatment methodologies. Anaerobic biodegradation has been recognized as an effective method for removing antibiotics and other pharmaceuticals from hospital wastewater, demonstrating the ability to degrade various antibiotic classes. This review critically examines the environmental fate of the antibiotics classes fluoroquinolones, sulfonamides, and diaminopyrimidines in hospital wastewater, emphasizing anaerobic biodegradation as an effective technology and the significance of the microbial community in this process. Furthermore, it examines ecotoxicological impacts across diverse species. The inappropriate disposal of inadequately treated hospital effluent into the environment disseminates antibiotics into freshwater, resulting in sublethal effects on aquatic fauna. The current research gap underscores the promise of anaerobic technologies, coupled with the toxicity assessment of treated effluents containing antibiotic mixtures, to improve comprehension of the environmental fate and effects of these antibiotic classes on aquatic vertebrate and invertebrate species.

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Soil heavy metal contamination is one of the most severe global environmental challenges today. Microbiologically induced calcite precipitation (MICP), as an environmentally friendly bioremediation technique, demonstrates significant potential in addressing such pollution. To optimize the MICP process, the research systematically investigated the influence of urea concentration on the remediation of soils co-contaminated with cadmium (Cd) and nickel (Ni). A highly efficient urease-producing strain, SX4 (Enterobacter sp.), was isolated from mining areas, showing the highest urease activity (conductivity change: 22.14 mS·cm⁻¹) among all isolates. Under optimal growth conditions (pH = 7, urea concentration 20 g·L⁻¹, OD₆₀₀ = 1.76), the remediation cycles for Cd– and Ni-contaminated soils were 120 h and 132 h, respectively. Evaluation of different urea concentrations (0, 10, 20, 40 g·L⁻¹) confirmed that the 20 g·L⁻¹ group was the most effective. It achieved effective removal rates of 45.71% and 43.34% for Cd and Ni, respectively, in single-pollutant contamination, and 32.44% for Cd and 38.75% for Ni, in co-polluted conditions. The findings elucidate the pivotal role of urea concentration in the MICP remediation process, providing crucial scientific evidence for optimizing the practical engineering parameters of this technology.

The dairy industry generates large volumes of whey, a nutrient rich by-product that is a threat to the environment because of a high lactose concentration. In this research, a potential of four microalgae strains – Tetradesmus obliquus MSCL 1710, Graesiella emersonii MSCL 1711, Chlorella vulgaris CCAP 211/111 and Scenedesmus quadricauda CCAP 276/16 was investigated to evaluate their growth under heterotrophic and mixotrophic conditions of lactose and its monosaccharides. This work specifically compares sweet whey (SW) and acid whey (AW) as a promising substrates for microalgal growth and lipid synthesis. Peculiar focus was given to local isolates—G. emersonii MSCL 1711 and T. obliquus MSCL 1710 cultivated in sweet (SW) and acidic whey (AW) at different concentrations and temperatures (15 °C and 25 °C). Mixotrophic cultivation in SW enhanced biomass productivity, with G. emersonii MSCL 1711 achieving 0.30 g/L/d and T. obliquus MSCL 1710 0.29 g/L/d at 25 °C. The highest lipid accumulation was observed in SW for G. emersonii MSCL 1711 at 15 °C, representing a 158.31% increase compared with the autotrophic control (mg/g dry weight). Additionally, β – galactosidase activity correlated with lactose assimilation in the medium for both cultures, suggesting that it is suitable for cultivation on whey substrates. The results confirm the ability of local microalgal strains to grow on SW, and on AW, demonstrating their potential for dairy by-product bioconversion into microalgal biomass for broad applications.

Diesel fuel is a complex petroleum compound that is considered an important and serious risk for organisms and their environment. There are different methods for soil cleaning from this compound, of which bioremediation is one of the best. This study was conducted to investigate the efficiency of Phanerochaete chrysosporium fungus in bioremediation of diesel fuel contaminated soil under oxygen-deficient conditions. In this study, soil samples free of petroleum compounds were manually contaminated with 3000 mg/kg of diesel fuel and incubated for 60 days at 30°C in a dark chamber. The amounts of CO₂ production, microbial growth, manganese peroxidase, and lignin peroxidase enzyme activities were measured every 10 days. The results indicated that the amount of CO₂ production in both pure and mixed cultures increased significantly from the beginning of the experiment to the 40th day, which was 22.96 and 25.53 mg/g/w, respectively. Manganese peroxidase and lignin peroxidase enzymes also first reached their maximum values on the 40th day, which were 225 U/L and 31.5 U/L, respectively, and then decreased. The average percentage of TPH degradation on different days showed that the biological decontamination rate of diesel fuel in pure and mixed culture was 79.62 and 83.17%, respectively, within 60 days. By comparing the biodegradation rate with other data, we concluded that P. chrysosporium can degrade diesel fuel under fermentation conditions and use its compounds to provide energy and carbon.

Industrialization, urbanization, and poor farming practices have led to major problems regarding potentially toxic elements (PTEs). PTEs in industrial effluents adversely affect water quality, soil, plants, and aquatic life, and ultimately cause severe health problems in humans. Several strategies have been utilized to overcome this serious environmental issue. The conventional methods most commonly used for this purpose are expensive and not environmentally friendly. Phytoremediation is a very cost-effective and eco-friendly strategy where researchers are focusing their efforts nowadays. This technique utilizes plants to remove PTEs from the soil. The efficacy of phytoremediation is enhanced by the microorganisms in the rhizosphere, where microbes utilize root exudates as their energy source, which in turn remove or solubilize PTEs from the soil. Microbes have adopted several mechanisms that directly and/or indirectly assist plants in resisting PTE stress. These mechanisms include biosorption, bioaccumulation, efflux systems, enzymatic detoxification, siderophore production, biosurfactants, extracellular sequestration, intracellular sequestration, ACC-deaminase, IAA production, and phytohormone production. Plant–microbe interaction is one of the most successful approaches that not only aids in remediating PTEs from the soil but also assists plant development. The efficiency of microbial activity could be enhanced by inserting PTE resistance genes so that genetically engineered microbes (GEMs) work more efficiently to remove PTEs from soil or water. The current review addresses the deleterious effects of PTEs on living organisms and discusses possible cost-effective and eco-friendly microbial-assisted phytoremediation strategies to remove PTEs from soil contaminated with industrial effluents.

Bioremediation is a promising method for removing heavy metals in contaminated effluents. Using several microorganisms, the process can provide efficient treatment, resulting in reduced waste generation, all while promoting sustainability. The current work evaluated the potential of the novel assembly by Rhodospirillum rubrum and Rhodobacter capsulatus to remove hexavalent chromium, total chromium, cadmium, and lead. In addition, photosynthetic pigment (bacteriochlorophyll-a and carotenoids) production and biomass increment were verified. A composite central design (CCD) was proposed to obtain models describing the behavior of the initial concentration of chromium, cadmium, and lead (independent variables). In the experiments described at the central point by the CCD, the co-culture (R. capsulatus: R. rubrum) was inoculated in 500 mL Erlenmeyer flasks containing an effluent consisting of RCV medium with heavy metals (20 mg/L Cr⁶⁺, 10 mg/L Cd²⁺ and 10 mg/L Pb²⁺). With a light intensity of 5760 lx and a biological cycle of 216 h, the maximum removals were 83% for total chromium, 30% for cadmium, and 80% for lead. Under these conditions, the biomass increased by 68% compared to the initial value (1.0 g/L), even in a highly toxic effluent.

The eradication of heavy metal contamination has emerged as a paramount objective in preserving and conserving global water resources. The present study highlights the potential of halophilic fungal melanin derived from Curvularia lunata as an eco-friendly, cost-effective, highly stable, and efficient biosorbent for removing toxic heavy metals. UV and FTIR spectroscopy characterization confirmed the presence of functional groups typical of eumelanin. Particle size analysis revealed a notable reduction in size from unmodified melanin (54.22–87.94 nm) to melanin nanoparticles (MNPs) (22.74–26.41 nm), indicating improved surface area for adsorption. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) data further validated the superior adsorption capabilities of MNPs compared to unmodified melanin. Specifically, the MNPs exhibited a 100% removal efficiency of over 18 metals out of 24 at a concentration of 0.15 mg/L and at pH 7, surpassing the performance of native melanin. X-ray photoelectron spectroscopy (XPS) was applied to specify the elemental composition of the solid surfaces and the chemical forms of adsorbed metals. Ultrasound-assisted extraction (UAE) significantly enhances adsorption efficacy by facilitating better dispersion and generating a higher surface area, thereby increasing the Number of active binding sites available on MNPs for heavy metal chelation. This mycoremediation-based approach presents a scalable and industrially adaptable solution for water detoxification, offering an advantageous alternative to conventional high-performance membrane technologies with minimal process modifications.