Search Results (310)

Carbon tetrachloride (CT) is a toxic volatile chlorinated hydrocarbon, posing a serious hazard to ecosystem and human health. This study discussed the bioremediation possibility of groundwater contaminated by CT. Enhanced reductive dechlorination bioremediation (ERD) was used to promote the reductive dechlorination process of CT by adding yeast extract as a supplementary electron donor. The microcosm samples of the Control and Experi group were setup in the experiment, and the CT degradation efficiency and microbial community structure changes over 150 days were monitored. The results showed that the Experi group achieved complete degradation of CT within 40 days, while the control group had no significant change. By analyzing the physical and chemical indexes such as VFAs, sulfate ions, oxidation–reduction potential, pH value and so on, the key changes in the degradation process of CT were revealed. Microbial community analysis showed that specific microorganisms such as Acinetobacter johnsonii, Aeromonas media and Enterobacter mori played a significant role in the degradation of CT. They may produce hydrogen through fermentation to provide electron donors for the reductive dechlorination of CT. In addition, the genes of reductive dehalogenase synthase related to CT degradation were also identified, which provided molecular evidence for understanding the biodegradation mechanism of CT. The results deliver a scientific basis for optimizing the bioremediation strategy of CT-contaminated groundwater. Full article

Petroleum-contaminated terrestrial ecosystems require effective bioremediation strategies. In this study, genomic analysis revealed key biodegradation genes on the Acinetobacter calcoaceticus 21# chromosome: alkane hydroxylases (alkB, almA, LadA) and aromatic ortho-cleavage pathway genes (catABC). Phylogenetic and multiple sequence alignment analyses of the almA gene in strain 21# revealed the presence of signature motifs characteristic of Baeyer–Villiger monooxygenase. Functional annotation analysis demonstrated stronger phylogenetic affinity of this protein to previously characterized BVMOs than to hydroxylases. Therefore, it is suggested that the AlmA protein in 21# exhibits BVMO activity and participates in the subterminal oxidation pathway of alkane degradation. Wild-type 21# degraded both n-Octacosane (24.47%) and pyrene (34.03%). Engineered 21#-A3 showed significantly enhanced n-Octacosane degradation (28.68%). To validate AlmA function and assess impacts of exogenous gene integration, we expressed the almA gene from A. vivianii KJ-1 via pET-28a(+)-av-almA-BH vector. Enzymatic assays demonstrated no activity toward long-chain alkanes but high activity for 2-decanone (0.39 U/mg) and 2-dodecanone (0.37 U/mg). Metabolite analysis confirmed recombinant AlmA functions through subterminal oxidation. This study establishes a foundational framework for advancing the optimization of petroleum-degrading bacteria. To engineer more efficient hydrocarbon-degrading strains, future research should integrate meta-cleavage pathways to expand their substrate utilization range for polycyclic aromatic hydrocarbons. Full article

The main objective of this study was to select indigenous fungal species suitable for the potential mycoremediation of the soils polluted by organic pollutants. As a sampling area, Litvínov City (North Bohemia, Czech Republic) was selected. The city is characterized by intensive coal mining, coal processing, and the chemical industry, predominantly petrochemistry. The elevated contents of persistent organic pollutants (POPs) such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were identified in urban soils due to the long-term industrial pollution. The results confirmed elevated contents of PAHs in all the analyzed soil samples with high variability ranging between 0.5 and 23.3 mg/kg regardless of the position of the sampling area on the city map. PCBs and PCDD/Fs exceeded the detection limits in the soil at the sampling points, and several hotspots were revealed at some locations. All the sampling points contained a diverse community of saprotrophic and mycorrhizal fungi, as determined according to abundant basidiomycetes. Fungal species with a confirmed ability to degrade organic pollutants were found, such as species representing the genera Agaricus from the Agaricaceae family, Coprinopsis from the Psathyrellaceae family, Hymenogaster from the Hymenogasteraceae family, and Pluteus from the Pluteaceae family. These species are accustomed to particular soil conditions as well as the elevated contents of the POPs in them. Therefore, these species could be taken into account when developing potential bioremediation measures to apply in the most polluted areas, and their biodegradation ability should be elucidated in further research. The results of this study contribute to the investigation of the potential use of fungal species for mycoremediation of the areas polluted by a wide spectrum of organic pollutants. Full article

Soil contamination with petroleum hydrocarbons is a serious environmental issue, necessitating the development of effective and environmentally friendly remediation methods that align with the principles of sustainable development. This study investigated the impact of selected biosurfactants on the efficiency of the biodegradation of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. Six biosurfactants—poly-γ-glutamic acid (γ-PGA), rhamnolipid, surfactin, a mixture of γ-PGA, rhamnolipids, and surfactin (PSR), as well as two commercial formulations (JBR 425 and JBR 320)—were evaluated in combination with a bacterial consortium. Biodegradation experiments were conducted under laboratory conditions for a 90-day period. The effectiveness of the tested biosurfactants was assessed using respirometric analysis, the chromatographic determination of the residual hydrocarbon content, and toxicity assays. The results showed that the application of a bacterial consortium enriched with a mixture of biosurfactants PSR (a biosurfactant concentration in the inoculating mixture: 5 g/dm³) was the most effective approach, resulting in an oxygen uptake of 5164.8 mgO₂/dm³ after 90 days, with TPH and PAH degradation rates of 77.3% and 70.32%, respectively. Phytotoxicity values decreased significantly, with TU values ranging from 6.32 to 4.62 (growth inhibition) and 3.77 to 4.13 (germination). Toxicity also decreased in the ostracodtoxkit test (TU = 4.35) and the Microtox SPT test (TU = 4.91). Among the tested biosurfactants, surfactin showed the least improvement in its bioremediation efficiency. Under the same concentration as in the PSR mixture, the oxygen uptake was 3446.7 mgO₂/dm³, with TPH and PAH degradation rates of 60.64% and 52.64%, respectively. In the system inoculated with the bacterial consortium alone (without biosurfactants), the biodegradation efficiency reached 44.35% for TPH and 36.97% for PAHs. The results demonstrate that biosurfactants can significantly enhance the biodegradation of petroleum hydrocarbons in soil, supporting their potential application in sustainable bioremediation strategies. Full article

The Arabian Gulf, bordered by major energy-producing nations, harbors diverse microalgal communities with strong potential for the bioremediation of environmental pollutants, particularly petroleum hydrocarbons. This review evaluates two key microalgal groups—micro-green algae and dinoflagellates—highlighting their distinct physiological traits and ecological roles in pollution mitigation. Dinoflagellates, including Prorocentrum and Protoperidinium, have demonstrated hydrocarbon-degrading abilities but are frequently linked to harmful algal blooms (HABs), marine toxins, and bioluminescence, posing ecological and health risks. The toxins produced by these algae can be hemolytic or neurotoxic and include compounds such as azaspiracids, brevetoxins, ciguatoxins, okadaic acid, saxitoxins, and yessotoxins. In contrast, micro-green algae such as Oedogonium and Pandorina are generally non-toxic, seldom associated with HABs, and typically found in clean freshwater and brackish environments. Some species, like Chlorogonium, indicate pollution tolerance, while Dunaliella has shown promise in remediating contaminated seawater. Both groups exhibit unique enzymatic pathways and metabolic mechanisms for degrading hydrocarbons and remediating heavy metals. Due to their respective phycoremediation capacities and environmental adaptability, these algae offer sustainable, nature-based solutions for pollution control in coastal, estuarine, and inland freshwater systems, particularly in mainland Qatar. This review compares their remediation efficacy, ecological impacts, and practical limitations to support the selection of effective algal candidates for eco-friendly strategies targeting petroleum-contaminated marine environments. Full article

Most large-scale crude oil spills occur in marine environments. We screened easily propagable/maintainable halophiles to develop agents for the bioremediation of marine spills. A bacterial strain isolated from a polluted region of the Great Salt Lake was characterized and tested for its ability to degrade crude oil. The strain (Salinivibrio costicola) is motile, catalase- and lipase-positive, a facultative anaerobe, and an obligate halophile. Its growth optimum and tolerance ranges are: NaCl (5%, 1.25–10%), pH (8, 6–10), and temperature (22 °C, 4–45 °C). Its genome (3,166,267 bp) consists of two circular chromosomes and a plasmid, containing 3197 genes, including some genes potentially relevant to hydrocarbon metabolism. The strain forms a biofilm but is considered nonpathogenic and is sensitive to some common antibiotics. Lytic bacteriophages infecting the strain are rare in the water samples we tested. The strain survived on desiccated agar media at room temperature for a year, grew optimally in complex media containing 0.1–1% crude oil, but failed to reduce total recoverable petroleum hydrocarbons from crude oil. Thus, a recalcitrant halophile may endure crude oil without mineralizing. Due to some of their advantageous attributes, such strains can be considered for genetic manipulation to develop improved agents for bioremediation. Full article

Heavy oil, due to its complex hydrocarbon structure and resistance to degradation, poses significant environmental challenges. There is a lack of knowledge about the biodegradability of heavy oil in the natural environment under aerobic and anaerobic conditions. In this study, we used microbial communities of water and soil samples to investigate the biodegradation of heavy oil. Gas chromatography (GC) analysis was used to measure residual oil. Under aerobic conditions, soil-derived microorganisms demonstrated significantly higher degradation efficiency—achieving up to 80.3% removal—compared to water-derived samples, which showed a maximum degradation of 52.1%. Anaerobic conditions, on the other hand, clearly slowed down degradation; the maximum degradation rates in water and soil samples were 43.7% and 11.1%, respectively. Although no clear linear relationship was found, the correlation between initial microbial populations and degradation performance revealed that higher counts of heterotrophic and oil-degrading bacteria generally enhanced biodegradation. Under anaerobic conditions, especially, persistent hydrocarbon peaks in both environments suggest the presence of recalcitrant heavy oil fractions such as polycyclic aromatic hydrocarbons. In conclusion, this study emphasizes the crucial roles microbial sources and oxygen availability play in maximizing bioremediation techniques for environments contaminated with heavy oil. Full article

The release of polycyclic aromatic hydrocarbons (PAHs) into the environment has become a serious concern with rapidly increasing human activities. PAHs are one of the hazardous pollutants generated primarily from the incomplete combustion of fossil fuels, industrial emissions, and the expenditure of vehicles. These toxic compounds are very dangerous to ecosystems and human health due to being persistent, bioaccumulative, and carcinogenic. Composting is considered a form of bioremediation for eliminating PAHs in contaminated soils. The method utilizes microbial communities to break down organic pollutants and is low-cost and environmentally friendly. The efficiency factor depends on many aspects, including soil pH, oxygen, temperature provision, and the diversity of microbes, among others. Thermophilic conditions help in the decomposition of both low- and high-molecular-weight PAHs. This paper focuses on the effectiveness of composting as a bioremediation technology for remediating PAH-contaminated soils and its impact on the environment and human health. Due to its safety and high efficiency, composting should be improved and prioritized for its widespread application as a principal remediation technology for PAH pollution at the earliest opportunity. Full article

Microorganisms from saline environments have garnered significant interest due to their unique adaptations, which enable them to thrive under high-salt conditions and synthesize valuable biomolecules. This study investigates the biosynthesis of biomolecules, such as extracellular hydrolytic enzymes, biosurfactants, and carotenoid pigments, by four newly halotolerant bacterial strains isolated from saline environments in the Băicoi (soil, water) and Curmătura (mud) area (Prahova County, Romania). Isolation was performed on two selective culture media with different NaCl concentrations (1.7 M, 3.4 M). Based on their phenotypic and molecular characteristics, the four halotolerant bacteria were identified as Halomonas elongata SB8, Bacillus altitudinis CN6, Planococcus rifietoensis CN8, and Halomonas stenophila IB5. The two bacterial strains from the Halomonas genus exhibited growth in MH medium containing elevated NaCl concentrations (0–5 M), in contrast to the other two strains from Bacillus (0–2 M) and Planococcus (0–3 M). The growth of these bacteria under different salinity conditions, hydrocarbon tolerance, and biomolecule production were assessed through biochemical assays, spectrophotometry, and high-performance thin-layer chromatography. The antimicrobial properties of biosurfactants and carotenoids produced by H. elongata SB8, B. altitudinis CN6, P. rifietoensis CN8, and H. stenophila IB5 were evaluated against four reference pathogenic microorganisms from the genera Escherichia, Pseudomonas, Staphylococcus, and Candida. H. elongata SB8 showed the highest hydrocarbon tolerance. B. altitudinis CN6 exhibited multiple hydrolase activities and, along with H. elongata SB8, demonstrated biosurfactant production. P. rifietoensis CN8 produced the highest carotenoid concentration with antifungal and antimicrobial activity. Exploring these organisms opens new pathways for bioremediation, industrial bioprocessing, and sustainable biomolecule production. Full article

Plastic containers used for diesel storage represent an underexplored but significant environmental challenge due to hydrocarbon retention and prolonged weathering. This study evaluates the capacity of Aspergillus flavus to colonize and grow on high-density polyethylene (HDPE) surfaces contaminated with weathered and fresh diesel residues. Circular plastic samples from HDPE tanks exposed to environmental conditions for over two years (weathered) and for less than two months (non-weathered) were inoculated with A. flavus and incubated at 20 °C, 25 °C, and 30 °C. Growth kinetics were assessed through radial expansion and halo formation, quantified via digital imaging and ImageJ analysis. Results showed the most robust fungal growth occurred on weathered diesel-contaminated gray plastics at 30 °C, with colony areas exceeding 350 mm² and halos over 3000 mm². Conversely, white HDPE with fresh diesel showed limited and inconsistent growth, likely due to the presence of volatile hydrocarbons and polymer additives. These findings underscore the critical role of diesel aging and polymer characteristics in shaping fungal adaptability, providing a foundation for the development of environmentally sustainable bioremediation strategies targeting diesel-contaminated HDPE plastics. Full article

The increasing global oil consumption has led to significant soil contamination by hydrocarbons, notably diesel-range hydrocarbons. Soil bioremediation through bacterial bioaugmentation is an alternative to increase the degradation of organic pollutants such as petroleum products. Bioremediation is a sustainable practice that contributes to the Sustainable Development Goals (SDGs) because it is environmentally friendly, reduces the impact of human activities, and avoids the use of invasive and destructive methods in soil restoration. This study examines the bioremediation potential of hydrocarbonoclastic bacteria isolated from soil close to areas with a risk of spills due to pipelines carrying hydrocarbons. Among the isolated strains, Arthrobacter globiformis, Pantoea agglomerans, and Nitratireductor soli exhibited hydrocarbonoclast activity, achieving diesel removal of up to 90% in short-chain alkanes and up to 60% in long-chain hydrocarbons. The results from in silico studies, which included molecular docking and molecular dynamics simulations, suggest that the diesel removal activity can be explained by the bioavailability of the linear alkanes and their affinity for alkane monooxygenase AlkB present in the studied microorganisms, since long-chain hydrocarbons had lower enzyme affinity and lower aqueous solubility. The correlation of the experimental results with the computational analysis allows for greater insight into the processes involved in the microbial degradation of hydrocarbons with varying chain lengths. Furthermore, this methodology establishes a cost-effective approximation tool for the evaluation of the feasibility of using different microorganisms in bioremediation processes. Full article

The influence of petroleum hydrocarbons (PHCs) on the transport and transformation of heavy metals may limit bioremediation efficiency. The mechanisms by which PHC degradation intermediates control heavy metal distribution in calcareous soils from karst areas require further exploration. This study systematically investigated how compositional changes in diesel fuel during aging regulated the fate of Cd and Pb in calcareous soils. The results demonstrated that the low-molecular-weight fractions of diesel fuel (C₁₀−C₁₆) were preferentially degraded. This degradation process altered zeta potential, cation exchange capacity (CEC), and pH, thereby promoting Cd stabilization through electrostatic attraction and speciation transformation. Particularly, reducible Cd content showed a strong positive correlation with C₁₆ content (r = 0.88, p < 0.05). Furthermore, the degradation of C₁₀−C₁₆ fractions caused Pb transformation from residual to bioavailable fractions by stimulating microbial activity. Residual Pb content was positively correlated with C₁₀−C₁₆ fractions (r = 0.55, p < 0.05). Notably, dissolved organic matter (DOM) and CaCO₃ content in calcareous soils enhanced Cd and Pb adsorption, thereby weakening the interactions between these metals and C₁₀−C₁₆ fractions. Consequently, multiple linear regression (MLR) models relying exclusively on C₁₀−C₁₆ degradation parameters showed poor fitting coefficients for Cd/Pb mobility. The present work provides scientific guidance for heavy metal bioremediation in calcareous soils. Full article

Tyre wear particles (TWPs), generated from tyre-road abrasion, are a pervasive and under-regulated environmental pollutant, accounting for a significant share of global microplastic contamination. Recent estimates indicate that 1.3 million metric tons of TWPs are released annually in Europe, dispersing via atmospheric transport, stormwater runoff, and sedimentation to contaminate air, water, and soil. TWPs are composed of synthetic rubber polymers, reinforcing fillers, and chemical additives, including heavy metals such as zinc (Zn) and copper (Cu) and organic compounds like polycyclic aromatic hydrocarbons (PAHs) and N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD). These constituents confer persistence and bioaccumulative potential. While TWP toxicity in aquatic systems is well-documented, its ecological impacts on terrestrial environments, particularly in agricultural soils, remain less understood despite global soil loading rates exceeding 6.1 million metric tons annually. This review synthesizes global research on TWP sources, environmental fate, and ecotoxicological effects, with a focus on soil–plant systems. TWPs have been shown to alter key soil properties, including a 25% reduction in porosity and a 20–35% decrease in organic matter decomposition, disrupt microbial communities (with a 40–60% reduction in nitrogen-fixing bacteria), and induce phytotoxicity through both physical blockage of roots and Zn-induced oxidative stress. Human exposure occurs through inhalation (estimated at 3200 particles per day in urban areas), ingestion, and dermal contact, with epidemiological evidence linking TWPs to increased risks of respiratory, cardiovascular, and developmental disorders. Emerging remediation strategies are critically evaluated across three tiers: (1) source reduction using advanced tyre materials (up to 40% wear reduction in laboratory tests); (2) environmental interception through bioengineered filtration systems (60–80% capture efficiency in pilot trials); and (3) contaminant degradation via novel bioremediation techniques (up to 85% removal in recent studies). Key research gaps remain, including the need for long-term field studies, standardized mitigation protocols, and integrated risk assessments. This review emphasizes the importance of interdisciplinary collaboration in addressing TWP pollution and offers guidance on sustainable solutions to protect ecosystems and public health through science-driven policy recommendations. Full article

The anthropogenic deployment of plastic waste, especially petroleum-based plastics with toxic hydrocarbons, presents a significant environmental and health threat in sub-Saharan Africa (SSA). Herein, the high demand and rapid plastic production, coupled with improper disposal and inadequate waste management, have led to widespread contamination of air, water, and soil. Conventionally, plastic waste management, such as incineration and recycling, provides limited long-term solutions to this growing crisis. This necessitates urgent, sustainable, and eco-friendly remediation techniques to mitigate its far-reaching environmental implications. This comprehensive review focused on sustainable and eco-friendly techniques by exploring strengths, weaknesses, opportunities, and threats (SWOT) analysis of plastic waste management. Bioremediation techniques were found as potential solutions for addressing plastic waste in SSA. This paper examines advancements in physiochemical methods, the challenges in managing various plastic types, and the role of enzymatic and microbial consortia in enhancing biodegradation. It also explores the potential of genomic technologies and engineered microbial systems to convert plastic waste into valuable products, including bioenergy via bio-upcycling. These bioremediation strategies align with the United Nations Sustainable Development Goals (UN SDGs), offering a promising path to reduce the environmental and health impacts of plastic pollution in the region. This paper also considers future directions of integrating AI-powered recycling systems to facilitate the development of a circular economy in SSA. Additionally, this paper provides progress and future perspectives on bioremediation as a sustainable solution for plastic waste management in SSA. Full article

Oil spills represent a significant environmental threat due to the toxicity of hydrocarbons, particularly in aquatic environments where oil rapidly spreads across the surface. Sustainable sorbents are needed for an efficient and eco-friendly response to oil spills. Cellulose aerogels produced from recycled paper and cardboard exhibit promising properties such as buoyancy, light weight, biocompatibility, and recyclability. Mechanical stability and reusability can be enhanced using cross-linkers such as starch. This study evaluated the impact of starch on cellulose aerogel morphology, sorption capacity for various petroleum products (crude oil, marine diesel, and lubricating oil), and reusability using scanning electron microscopy (SEM) and elemental mapping. Aerogels containing 0.5 and 1 wt% starch showed higher porosity, sorption capacity, and reusability. Starch did not affect hydrophobization or significantly alter nitrogen and carbon levels, indicating limited influence on surface chemistry and adsorption performance. Full article