Biodegradation最新文献

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.

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.

Phenoxyalkanoic acid herbicides are widely used in agricultural lands to kill the weeds in crop fields and have a very detrimental effect on soil’s natural fertility and its microbiome. Bacterial culture isolated from these lands in the presence of herbicides group 2,4-Dichlorophenoxyacetic acid (2,4-D) and 2-Methyl-4-chlorophenoxy acetic acid (MCPA) belongs to plant growth hormone auxin. Strain LKDC4 Pseudomonas aeruginosa exposed to both herbicides at a range of concentrations 300 mg/L, 500 mg/L and 700 mg/L for 5 days without any enrichment culture, providing 2,4-D and MCPA as a carbon source for survival. LKDC4 shows a maximum number of cell growth in 2,4-D herbicide at the lowest concentration 300 mg/L (1.35 mM) comparatively with the highest concentration 700 mg/L (3.16 mM) of optical density 0.85 and 0.78 at 600 nm, respectively. At the same time, this strain shows a similar number of cell growth at all three concentrations 300 mg/L, 500 mg/L, and 700 mg/L of 1.49 mM, 2.49 mM, and 3.48 mM respectively of optical density 0.90 at 600 nm. The degradation efficiency of the Pseudomonas aeruginosa LKDC4 was 70 to 80% of 2,4-D herbicide when the growth medium contained 0.2% glucose as the only carbon source after 5 days at optimum conditions. The degradation of MCPA was 100% at 300 mg/L and 700 mg/L, while 81% degradation at 500 mg/L after 5 days of incubation at optimum conditions. P. aeruginosa can degrade both herbicides and survive well in their presence, making it a tolerant microbial strain.

Polyethylene terephthalate (PET) is a huge part of consumer products such as beverage bottles, packaging materials, and textile fibres. It contributes significantly to persistent plastic pollution in freshwater ecosystems. This study explores the biodeterioration potential of seven indigenous freshwater microalgae isolated from water bodies near Indore, India, for sustainable PET degradation without chemical pre-treatment. Algal strains were incubated with PET granules for 20 days under controlled laboratory conditions (pH-7.2, temp. 27 ± 3 °C, light intensity of 40.5 µmol/m²/s, and a 12:12 h light–dark period). The average specific growth rate (μ) of the microalgal strains was 0.07 ± 0.01 μ/day. Among these, Asterarcys quadricellulare exhibited the highest deterioration efficiency, achieving a weight loss of 10%, followed by Scenedesmus sp. with a weight loss of 6%. Scanning electron microscopy (SEM), ATR-FTIR spectroscopy, and X-ray diffraction (XRD) analysis revealed notable cracks, chemical alterations, and reduction in crystallinity, respectively. Transmittance intensity of the characteristics FTIR spectra at 1715 cm⁻¹ demonstrated a sharp increase, indicating the formation of carbonyl groups. The reduction in the crystallinity of PET granules was consistently demonstrated by both FTIR and XRD analyses, confirming structural deformities induced by the algal strains. Biochemical analysis revealed that strains A. quadricellulare, C. proboscideum, and P. daitoensis exhibited a significant increase in lipid, protein, and carbohydrate concentration compared to the control. This study highlights the efficacy of unicellular microalgal strains in mitigating PET pollution in aquatic systems while enabling biomass valorisation for other sustainable applications.

The escalating global production and usage of paracetamol (C₈H₉NO₂), a widely administered analgesic and antipyretic pharmaceutical, has led to its ubiquitous presence in environmental matrices, including surface waters, municipal wastewater, and even potable water sources. Owing to its persistence and bioaccumulative potential, paracetamol poses a significant ecotoxicological threat, particularly through trophic transfer in aquatic ecosystems. Conventional wastewater treatment methods often fall short in completely eliminating such micropollutants. In this context, bioremediation offers a promising, sustainable, and cost-effective alternative for pharmaceutical remediation. This study investigates the anaerobic degradation potential of two sulfate-reducing bacterial consortia, designated Consortium I and Consortium II, isolated from Okhla landfill leachate and enriched with distinct Postgate media formulations. Paracetamol was introduced at varying concentrations (50–500 mg/L), with and without supplementation of an auxiliary carbon source, sodium lactate. Metagenomic profiling via 16S rRNA sequencing revealed that Consortium I was primarily composed of Clostridium (40.1%) and Acidipropionibacterium (31.2%), whereas Consortium II exhibited a dominant presence of Clostridium (80.3%) and Bacillus (7.99%). Consortium II exhibited superior degradation kinetics, achieving complete removal of 500 mg/L paracetamol in 48 h under lactate-free conditions. Conversely, the presence of sodium lactate significantly attenuated degradation efficiency, suggesting substrate competition and metabolic preference. Gas chromatography-mass spectrometry (GC-MS) identified 4-aminophenol and hydroquinone as transient intermediates, supporting a proposed anaerobic degradation pathway for paracetamol. These findings underscore the potential of native sulfate reducing bacterial consortia in the bioremediation of contaminants and provide mechanistic insight into anaerobic paracetamol degradation, offering a viable strategy for enhanced treatment efficacy of contaminated waste streams.

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