Biodegradation最新文献

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.

Polymer flooding technology enhances crude oil recovery but generates a large amount of wastewater containing hydrolyzed polyacrylamide (HPAM) and HPAM residue in oil reservoirs, which induce serious environmental problems. Effective degradation of HPAM is highly required in oilfields, especially biodegradation technologies. Ten strains of HPAM degrading bacteria have been screened and identified from oilfield wastewater. An optimal HPAM biodegradation system of composite bacteria has been established based on two strains Agrobacterium pusense NMYGYA2 and Stutzerimonas balearica SCE1. The HPAM biodegradation performance of the composite bacteria has been improved through cultivation condition optimization. The highest HPAM removal rate of 81.2% could be achieved at the optimized condition with the addition of 800 mg·L⁻¹ urea, 500 mg·L⁻¹ glucose and 50 mg·L⁻¹ CaCl₂. The gel permeation chromatography results showed that the HPAM molecular weight decreased from 3.7 × 10⁶ Da to 1.9 × 10⁵ Da after the composite bacterial degradation. Fourier transform infrared spectroscopy analysis revealed the hydrolysis of NH₂ group and the cleavage of C–C bond. Furthermore, the composite bacteria exhibited the ability to break down HPAM gels via biodegradation at temperatures up to 55 °C, indicating that they can be used to treat the blocking in reservoirs with a temperature < 55 °C and ground facilities.

Diesel oil is a fossil fuel widely utilized globally and a significant source of environmental contamination. Its presence poses substantial ecological challenges. Bioremediation emerges as a viable solution for restoring diesel-contaminated environments, contingent upon comprehending the local microbiota. This study employed a metabarcoding technique with a culture-dependent approach to assess the impact of hydrocarbon contamination on soil microbiota. Soil samples were collected from contaminated areas, and microbial diversity was assessed through relative abundance, alpha, and beta diversity analyses. Additionally, bacterial strains isolated from the same area were screened for their ability to degrade hydrocarbons. Four strains, Pseudomonas nitroreducens B32, Pseudomonas koreensis B11, Ralstonia sp. BC2, and Acinetobacter sp. BC3 could degrade up to 38% of the diesel, using it as the sole carbon source. These strains effectively degraded n-alkanes and cyclic alkanes with short and medium chains (C7 to C18). This research enhances the understanding of hydrocarbons’ impacts on soil microbiota and underscores the potential application of microorganisms in bioremediation efforts.

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