Biodegradation最新文献

The persistent inefficiency of landfill operations and plastic waste management in South Africa has intensified environmental contamination, underscoring the urgent need for innovative bioremediation strategies. This study aimed to identify and evaluate fungal isolates from landfill soils for their ability to biodegrade polyethylene (PE), thereby contributing to sustainable plastic waste management solutions. A total of eighteen fungal isolates were recovered from local landfill soils using plastic-enriched soil dilution techniques. These isolates were screened for PE biodegradation by incubating pre-weighed polyethylene strips with each fungal culture for 45 days at ambient temperature. Biodegradation efficiency was assessed through gravimetric weight loss, while structural alterations in the polymer matrix were examined using fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Several isolates demonstrated significant PE degradation, including the novel PE degraders Arthrographis kalrae SP5INT, Lecanicillium coprophilum SP7MK, and Didymosphaeria variabile SP11INT, reported here for the first time. Penicillium chrysogenum SP17MK and Engyodontium album SP3MK showed the highest degradation rates, achieving over 20% weight loss. FTIR analysis revealed the appearance of carbonyl groups (~ 1700 cm⁻¹) and a reduction in characteristic PE peaks at 719 and 1472 cm⁻¹, suggesting oxidative degradation. SEM imaging further confirmed surface erosion and structural disintegration of the polymer, supporting the biochemical evidence of degradation. These findings represent the first report of novel fungal species capable of degrading PE in South African landfill soils and significantly expand the known diversity of plastic-degrading fungi. This work highlights South Africa's emerging role in microbial bioremediation research and provides a foundation for the development of locally relevant, biologically based plastic waste management strategies.

One of the most common soil pollutants on a global scale is fuel, which is fundamental for daily activities. Biodegradation has been regarded as an ideal remediation technique for hydrocarbon pollution. We investigated the potential of 28 Streptomyces species inhabiting different hydrocarbon-polluted soils for the biodegradation of petroleum. The tested isolates were cultured on mineral salts broth containing 2% crude oil as the sole carbon source. Gravimetric analysis of residual crude oil was performed, and the samples that showed the highest percentage of biodegradation were also analyzed via gas chromatography. Among the isolated actinobacteria, Streptomyces aurantiogriseus strain NORA7 (EMCC 28565) stood out for its ability to degrade crude oil (66.28 ± 6.25%). Gas chromatography revealed that docosane, nonadecane, pentacosane, and 7-methylpentadecane were the major compounds detected in the residual treated crude oil. Plackett–Burman design (PB) was used to determine the critical factors impacting the biodegradation process. Response surface methodology (RSM) through Central Composite Design (CCD) was subsequently conducted, and the predicted optimum point of crude oil biodegradation was at 3% crude oil concentration, 0.15 g/L yeast extract, and 25 mm inoculum size. The experimental value after optimum conditions was 70% after 3 weeks, which was close to the predicted value. A pot experiment was performed to investigate the outcomes of ex situ soil bioremediation, and the results were consistent with those of the flask-scale biodegradation experiment with enhanced removal of crude oil (92%). The results revealed that the ability of S. aurantiogriseus NORA7 to biodegrade crude oil could significantly contribute to the eco-friendly recovery of oil-polluted ecosystems and reduce the long-term environmental impact of crude oil pollution.

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Heavy metal contamination of the environment is a serious issue, and more efficient and effective bioremediation techniques are needed. This review introduces current heavy metal bioremediation techniques, with focus on phytoremediation and microbial remediation, and recent developments in biochar and CRISPR-Cas9 technology. Phytoremediation employs the natural process of plants to accumulate and detoxify metals as an eco-friendly and sustainable technique. Microbial remediation by fungi and bacteria provides an additional approach through reduction, sequestration, and transformation of metals. Biochar as a high-carbon value-added pyrolytic biomass product improves soil quality, increases microbial activity, and adsorbs heavy metals, making bioremediation more effective. The discovery of CRISPR-Cas9 revolutionized gene engineering by allowing gene editing of plants and microbes to improve their metal tolerance and degradation. This review outlines recent developments, synergistic uses of biochar and CRISPR-Cas9, and how they might enhance phytoremediation and microbial remediation. By combining such novel technologies, strong, sustainable, and scalable solutions could be built for curbing heavy metal pollution and safeguarding environmental health.

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This study aimed to produce, purify, and characterize laccase from Lentinus berteroi U21-2, for its potential application in the biodegradation of micropollutants. The fungus was cultivated in a liquid medium for 15 days at 28 °C in the dark. The enzymatic extract was purified using chromatographic techniques, and its molecular mass was determined through gel filtration, SDS-PAGE, and peptide mass fingerprint analysis. The optimum pH, temperature, and residual activity were evaluated using ABTS, guaiacol, and syringaldazine as substrates. UV-Vis spectroscopy and LC-MS/MS techniques were used to assess the laccase biodegradation of micropollutants. The laccase was 3.2-fold purified, and gel filtration estimated its molecular mass at 79.7 kDa, while SDS-PAGE revealed two bands of approximately 66 kDa and 50 kDa, being the ~50 kDa band a fragment. The purified enzyme demonstrated maximum activity at pH 4.5 and 30 °C, retaining 80% of its activity for 58 hours, and a higher affinity for syringaldazine as indicated by the K_M. The purified laccase effectively reduced the initial concentration of β-estradiol by 82%, diclofenac by 70%, and bisphenol-A by 30%, but showed no degradation of ibuprofen. These findings highlight the potential of L. berteroi laccase as a promising biocatalyst for the biodegradation of micropollutants.

The conventional physicochemical processes of lead removal from contaminated wastewater are cost-intensive and generate toxic secondary wastes. Therefore, employing bacteria capable of lead biosorption will serve as a green, sustainable, safe and inexpensive process for lead removal, and its integration with polyhydroxyalkanoate (PHA) production will generate revenue. To integrate these two processes, Bacillus paramycoides isolated from the lake water were analyzed for lead biosorption and PHA production in mineral salt media containing lead nitrate at different incubation times. The bacterium showed a high lead biosorption of about 423 mg/g of biomass at 72 h of incubation, which was earlier not reported. Bacillus paramycoides produced polyhydroxybutyrate by utilizing sucrose in the media. The lead ions enhanced the PHA production up to 35.7% CDW in bacterial cells by inducing oxidative stress, and the ability of PHA polymer to adsorb lead ions prevented further oxidative damage to the cells. This study is the first report on using an integrated process approach for lead biosorption and PHA production in bacteria.

To alleviate the detrimental impacts of zinc-containing wastewater on biological nitrogen removal systems, Pseudomonas hunanensis SK-4 was isolated and screened from a heavy industrial wastewater treatment facility. The efficient heterotrophic nitrification aerobic denitrification ability of Pseudomonas hunanensis was confirmed for the first time. The maximum removal efficiencies achieved by strain SK-4 for ammonium (100 mg/L), nitrate (100 mg/L), and nitrite (50 mg/L) were 99.81%, 82.31%, and 96.10%, respectively. Under the conditions of C/N 10, 35 °C, pH 7, 140 rpm, inoculum size 3%, with sodium citrate utilized as the carbon source, NH₄⁺-N was effectively removed. The nitrogen removal mechanisms employed by strain SK-4 were revealed through detailed whole-genome sequencing analysis. The nitrification and denitrification efficiencies of strain SK-4 were not affected under 100 mg/L Zn(II) stress. The inhibitory effects of varying Zn(II) concentrations on the nitrogen removal efficiency of strain SK-4 were predicted through model fitting. Such results showed that strain SK-4 had strong tolerance to Zn(II). The complete metabolic mechanisms of tolerance, transport, regulation and detoxification of Zn(II) in strain SK-4 were elucidated. Such findings indicated that strain SK-4 has a strong potential for the treatment of Zn(II) and nitrogen composite pollutants.

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Phthalate esters (PAEs) are widely used as plasticizers and beneficiation flotation agents in ore smelters, which are ubiquitously distributed emerging contaminants in the environment. The biodegradation of PAEs by degrading microbes is a promising method for their remediation. In this study, we isolated a novel PAE-degrading bacteria, Sinomonas sp. S2, from a contaminated area of a metal(loid) smelter in Guangxi Zhuang Autonomous Region, China. Strain S2 is capable of degrading short-chain PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butyl phthalate (DIBP) and di-n-butyl phthalate (DBP). Sinomonas sp. S2 can completely degrade DBP at concentrations of 400 mg·L⁻¹ within 24 h. The degradation kinetics of PAEs followed the modified Gompertz model. Strain S2 demonstrated good environmental adaptability thriving at pH ranging from 5 to 9 and temperatures between 20 and 40 °C, indicated by its growth on DBP. The optimal pH and temperature for degradation were found to be 7 and 40 °C, respectively. Additionally, several metabolites of DBP were identified, including phthalic acid (PA), butyl acetate, ethyl propionate and methyl 2-methylbutyrate. The reconstructed degradation pathway of DBP may involve protocatechuic acid, β-carboxy-cis, cis-mucronate and γ-carboxy muconolactone, ultimately leading to the tricarboxylic acid (TCA). In a bioaugmentation experiment involving soil artificially contaminated with DBP, strain S2 could promote the degradation of DBP in soil. The results indicate that strain S2 had high degradation capacity and environmental tolerance, which had the potential to be applied in the bioremediation of DBP-contaminated environments.

The present study investigates the physicochemical, heavy metal, and microbiological characteristics of water and sediment samples from the Buckingham Canal, Chennai, to assess environmental pollution and explore the bioremediation potential of native bacterial isolates. The water and sediment samples revealed the concentration of heavy metals in the sequence Zn > Mn > Pb > Cu > Cr and Zn > Mn > Cu > Cr > Pb. Among 25 isolates, BCSS04 showed exceptional resistance, tolerating up to 2100 ppm (Pb), 1900 ppm (Zn, Mn, and Cr), and 1300 ppm (Cu), identified as Proteus mirabilis through 16S rRNA sequencing (GenBank accession: PP980976.1). Molecular analysis confirmed the presence of the pbrA gene, while antibiotic susceptibility profiling revealed multidrug resistance, suggesting potential co-selection of metal and antibiotic resistance traits. Growth profiling under metal-induced stress revealed the highest bacterial growth under Mn (0.654 to 0.996) and Pb (0.623 to 0.984). Uptake studies confirmed efficient biosorption capabilities, with peak Pb and Zn uptake reaching 4.23 and 4.21 mg/g, respectively, at 100 ppm. Bioaccumulation assays supported these findings, with maximum accumulation rates for Zn (69.67%) and Pb (67.11%) at 100 ppm, gradually decreasing with increasing concentrations due to saturation or stress effects. SEM and FTIR analyses demonstrated structural and biochemical changes in Proteus mirabilis under metal stress. Molecular docking further revealed strong interactions between heavy metals against Metallothionein SmtA exhibited the strongest interaction with Zn (binding energy: -9.8 kcal/mol), involving eight active residues (TYR A:18, GLY A:53, ASP A:73, ASP A:50, GLU A:55, ARG A:26, HIS A:119, GLY A:52). The integrated physiological, biochemical, and molecular insights affirm the potential of Proteus mirabilis as a promising candidate for bioremediation of heavy metal-contaminated environments.

Sodium dodecyl sulfate (SDS), a widely used anionic surfactant, is a pervasive aquatic pollutant with documented ecotoxicity and persistence in the environment. In this study, we investigated metabolic response of the filamentous, heterocytous cyanobacterium Fischerella sp. lmga1 under sulfur starvation, focusing on its capacity to degrade SDS and utilize it as an alternative sulfur source. Sulfur-deprived cultures supplemented with 150 µM SDS initially exhibited chlorosis and physiological stress, but showed significant recovery by 14 days, including increased growth and better photosynthetic performance. A significant rise in intracellular sulfur content was observed, suggesting active sulfur acquisition. Expression analysis revealed strong induction of genes involved in sulfur uptake and assimilation (e.g., cysT, cysW, sbp, sat), alongside an ~ 880-fold upregulation of sdsA1 on day 10, encoding an SDS hydrolase. Correlation analyses showed that increased sdsA1 expression coincided with improvements in viability and sulfur status. This underscored a coordinated mechanism of SDS degradation and concomitant sulfur assimilation in Fischerella, indicating towards a novel adaptive strategy. Thus, this study establishes Fischerella as a promising candidate for bioremediation of sulfonated pollutants in aquatic systems and expands the knowledge of metabolic plasticity of cyanobacteria.