Biodegradation最新文献

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.

Graphical abstract

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.

Graphical abstract

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.

Microplastics (MPs) generated from major plastic polymers have impacted the environment and formulation of an end-of-life scenario is a need of the hour. In the current study, the effects of inoculum to substrate ratios (ISR) 2, 4 and 6 on the MPs from polyethylene (PE), polypropylene (PP) and polylactic acid (PLA) under thermophilic and mesophilic anaerobic digestion (AD) conditions was studied. The results indicated thermophilic AD to be a prospective method for PLA degradation with a maximum cumulative biogas production of 894.08 NmL/gVS_added at ISR4 and 89.62% of volatile fatty acids (VFA) was utilised during 148 days of incubation. However, the thermophilic AD of PP and PE was observed to be highly inefficient with a maximum biogas production of 111.64 and 47.48 NmL/gVS_added and also resulted in VFA accumulation. Under mesophilic AD conditions, PLA degradation was highly inefficient due to long hydrolysis time, whilst inhibition was noticed with both PP and PE. The microbiological study revealed the abundance of Firmicutes and Synergistota, genus D8A-2, Thermovirga and Candidatus Caldatribacterium during thermophilic AD of PLA. An abundance of Methanothermobacter indicated hydrogenotrophic methane production as the major pathway for methanogenesis during thermophilic AD of MPs. An abundance of PWY-3781 associated with detoxification of reactive oxygen species was observed in the AD of PP and PE. Overall, the study provided insight into the prospects for improving thermophilic AD for PLA.

The current study’s primary objectives were to screen for novel FPase-producing bacteria and optimize hydrolysis conditions for alkali-thermally pretreated sugarcane bagasse. This study carefully screened cellulolytic bacteria from soil and identified KH-08 as a potent FPase-producing strain. Based on 16S ribosomal RNA and gyrA gene sequences, KH-08 was identified as Bacillus velezensis, a newly found microbe capable of producing FPase. Experiments were conducted to optimize FPase-producing parameters such as fermentation time, temperature, and pH. The study improved FPase output by refining these parameters using Box-Behnken Design (BBD) and Response Surface Methodology (RSM). The derived quadratic polynomial model demonstrated great dependability (R² = 99.8%) and interactions that are statistically significant (P < 0.05). The ideal fermentation conditions—6 days, 30 °C, and pH 6.5—resulted in the greatest FPase activity of 75.93 U/L. The remarkable enzyme yield achieved under mild conditions clearly demonstrates the superiority of Bacillus velezensis KH-08 over previously reported cellulolytic strains. This exceptional performance underscores its potential as a highly promising candidate for industrial-scale bioconversion, with direct implications for bioethanol production, biomass valorization, and waste to energy technologies.

The application of metabolomic analysis to the study of fungal cell physiology provides a valuable means of elucidating the metabolic diversity of fungi. This study aims to identify metabolites that distinguish the metabolism of moulds based on the phosphorus source used in the culture medium, either inorganic phosphate (Pi) or phosphonoacetic acid (PA). A targeted metabolomics approach, using LC–MS combined with chemometric tools, facilitated the identification of metabolic differences between three fungal strains of the Penicillium genus: Penicillium commune, Penicillium crustosum S2, and Penicillium funiculosum S4. The availability of PA in the medium enables P. commune to synthesize compounds that stimulate cellular responses to unfavorable environmental conditions, while activating pathways involving precursors of secondary metabolites. Comparative analysis of cell-free extracts from P. commune and P. funiculosum S4 cultured on Pi-containing medium revealed increased levels of metabolites, including tyrosine, tryptophan, glutathione, and ethyl-3-hydroxybutyrate, in both fungal extracts. Furthermore, analysis of the cell-free extracts obtained from biomass grown on a medium containing PA showed similarities between P. commune and P. crustosum S2, as well as between the two wild strains. From these results, it can be concluded that the metabolic strategies of P. commune and P. funiculosum S4 are similar when Pi is the sole phosphorus source, whereas the use of phosphonate reveals common characteristics between the P. commune strain and P. crustosum S2. These observations allowed the identification of fungal biomarkers and provided insights into the mechanisms of metabolic response to changing environmental conditions.

Plastics are widely utilized across various industries, but their persistent accumulation in the environment has become a major ecological concern. Biodegradable alternatives offer a potential solution to plastic pollution; however, their degradation behavior under environmentally relevant conditions remains underexplored. This study evaluates the aerobic biodegradation of four polymer materials: starch, commercial thermoplastic starch of polyester origin (TPS1), linear low-density polyethylene (LLDPE), and a co-polyester thermoplastic starch (TPS2), over 180 days at 25 °C in a compost-soil matrix using the testing protocols of ASTM D5988-18 for carbon dioxide (CO₂) evolution. Microbial community dynamics were profiled using 16S rRNA and ITS2 amplicon sequencing. TPS2 reached complete mineralization (~ 100%) in 28 days, followed by starch at 71.1% by day 180. TPS1 showed partial mineralization of 38.6%, while LLDPE showed minimal mineralization (21.9%) as expected. Alpha diversity revealed higher bacterial richness in starch treatments and a marked reduction in fungal diversity in TPS1 and LLDPE. Differential abundance testing revealed significant microbial shifts between treatments. Linear discriminant analysis Effect Size (LEfSe) identified polymer-specific microbial biomarkers, including Paenibacillus and Botryotrichum for starch, Acrophialophora and Mycothermus for TPS2, and the Mycobacterium for LLDPE. Subgroup 10 Acidobacteria was uniquely enriched in TPS2-treated samples. These taxa reflect substrate-driven microbial selection. Coupling CO₂ mineralization with microbial profiling offers a practical framework to evaluate polymer biodegradability and guide the design of soil-degradable bioplastics. Overall, these findings demonstrate that polymer composition significantly influences microbial community structure and mineralization performance under mesophilic conditions.