Biodegradation最新文献

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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Oil sludge contains high levels of heavy chain petroleum hydrocarbons and heavy metals that hinder its biodegradation. Hence for successful remediation, selecting potent isolates and construction of efficient bacterial consortium is inevitable. The aim was to achieve bacterial consortium with the ability to tolerate harsh environment of oil sludge and degrade different hydrocarbon fractions of it. For this purpose, native oil-degrading and biosurfactant-producing bacteria were screened from oil tanks bottom sludge and were evaluated for their salt and heavy metal tolerance. Also, oil-degrading potentials of the isolates as well as their consortium were assessed through GC-FID analysis under both static and shaking conditions. The potential of sugarcane vinasse as a low-cost culture medium for large scale culture of the isolates as well as their immobilization and long-term viability on porous carriers including diatomaceous earth, sugarcane bagasse, and biochar were also investigated. The results showed that A. lactucae strain Ib-30 had the highest hydrocarbon degradation (~ 77%) and high level metal resistance. The oil-degrading efficiency of bacterial consortium was lower than that of individual isolates. S. warneri strain Ae1-30 was identified as the most halotolerant and metal-resistant isolate. Vinasse supported the growth of all strains, with C. hisashii strain T1-50 showing the highest proliferation rate. Sugarcane bagasse outperformed other carriers in maintaining bacterial viability over 14 months. Overall, these findings demonstrate the feasibility of scalable, sustainable bioremediation of oil sludge using potent indigenous bacterial resources and effective bio-carriers, offering a promising solution for industrial waste management.

Lignite, a low-rank coal, is commonly utilized as a fuel source. However, its high sulfur and ash content can result in the release of harmful substances during combustion. Microbial coal degradation offers a more environmentally friendly alternative to traditional chemical and physical methods of coal treatment. In this study, we obtained a bacterium, named as Cupriavidus sp isolated from activated sludge that exhibits potential for lignite degradation. After identification via 16S rDNA sequencing, the degradation characteristics and mechanisms of strain S4 on lignite from Shanxi, were systematically evaluated. Extracellular enzyme activities of strain S4 were measured, revealing the secretion of lignin peroxidase, manganese peroxidase, laccase, alkaline protease, and amylase, indicating its capacity for multi-enzyme synergistic degradation. Scanning electron microscopy (SEM) observations confirmed that the bacterium could adsorb onto the coal surface. Fourier transform infrared spectroscopy (FTIR) analysis demonstrated a significant increase in free hydroxyl groups on the coal, which facilitates degradation. Gas chromatography-mass spectrometry (GC–MS) and three-dimensional fluorescence spectroscopy analyses of the liquid-phase products showed a notable increase in long-chain alkanes and phenolic compounds in the degradation liquid, along with the detection of humic substances. Further studies indicated that strain S4 mediates initial adsorption through the secretion of extracellular polymers (EPS) rich in proteins and polysaccharides, highlighting the key mechanism of microbial-coal interface interaction. This study provides a theoretical foundation for the development of lignite bioremediation technologies and the resource-based application of functional bacterial strains.

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Crude oil pollution poses a threat to soil ecosystems, particularly in oil-producing regions. This study assessed the biodegradation potential of biofilm-forming Bacillus tropicus UCB and Pseudomonas aeruginosa SYLI isolated from crude oil sludge. Sludge samples were seasonally collected and bacterial counts determined using standard methods while microbial enrichment was conducted in mineral salt medium containing 1% crude oil. Biofilm formation was assessed using Congo red agar and microplate assays. Isolates were identified through cultural, biochemical, and 16S rDNA analysis. Dose–response toxicity test examined degradation across 1%, 3%, 7%, and 10% crude oil concentrations, while PAHs degradation in soil microcosm was analysed using GC–MS. Seasonal variations significantly influenced bacterial populations, with highest count (1.53 × 10⁸ CFU/mL) in the dry season and the least 3.17 × 10⁶ CFU/mL) during wet season. Optical density peaked at 2.86 nm in enrichment III. Results revealed molecular identities of the isolates as B. tropicus UCB and P. aeruginosa SYLI. Both isolates metabolized crude oil from 1 to 10%, with B. tropicus producing 601 mg/L CO₂ with 10% at day 12 and P. aeruginosa yielding 616 mg/L with 1% at day 4. In addition, results showed over 99% removal of low molecular weight PAHs and 75% degradation of high molecular weight PAHs, upon biostimulation. These findings highlight complementary strengths of B. tropicus on high-oil loads and P. aeruginosa rapid initial degradation at lower concentrations. This study suggests that biofilm formation coupled with biostimulation may improve bacterial efficiency in bioremediation. It also represents the first in vitro report on PAHs degradation by Bacillus tropicus.