Biodegradation最新文献

The widespread use of pesticides, including diazinon, poses an increased risk of environmental pollution and detrimental effects on biodiversity, food security, and water resources. In this study, we investigated the impact of Potentially Toxic Elements (PTE) including Zn, Cd, V, and Mn on the degradation of diazinon in three different soils. We investigated the capability and performance of four machine learning models to predict residual pesticide concentration, including adaptive neuro-fuzzy inference system (ANFIS), support vector regression (SVR), radial basis function (RBF), and multi-layer perceptron (MLP). We employed a 10-fold cross-validation mechanism to evaluate the models. Moreover, performance validation of selected algorithms through the coefficient of determination (R²), root mean square error (RMSE), mean absolute error (MAE) and mean square error (MSE) confirm that the SVR and ANFIS with lower RMSE, MSE, and a higher R² can simulate the degradation process better than other models. The result showed that both SVR and ANFIS approaches worked well for the data set, but the SVR technique is more accurate than the fuzzy model for estimating pesticide concentration in soil in the presence of PTE. Vanadium appeared to be the best option for the degradation of diazinon. The models predicted the performance of V²⁺ for diazinon degradation with R² and RMSE of 0.99 and 2.18 (mg.kg^{-1}) for SVR and, 0.99, and 1.30 for the ANFIS model for the training set. Finally, the high accuracy of the models was confirmed.

This study focused on a new approach for valorization of both ground tire rubber (GTR) and nitrate-containing wastewater via simultaneous devulcanization and denitrification. Initially, sulfur-based autotrophic denitrifiers were successfully enriched from three different seed sludge sources, biological nutrient removal (BNR) sludge, anaerobic digester sludge and BNR sludge of a leather organized industrial zone WWTP. Average nitrate removal efficiencies were 96–98%. Biological devulcanization (biodevulcanization) of GTR was later investigated with these enriched cultures. Results revealed that biodevulcanization was only achieved with the culture enriched from BNR sludge of the leather organized industrial zone WWTP, as 3.9% sulfur removal (desulfurization efficiency). Metal sulfate precipitation was speculated to cause an underestimation of the desulfurization ratio. Fourier-transform infrared spectroscopy (FTIR) results demonstrated a decrease in the intensity of the C–S bonds and an increase in intensity of S–O bonds in treated GTR samples. This was attributed to the oxidation of sulfidic crosslinks, i.e. verification of biodevulcanization. This study indicated that simultaneous biodevulcanization and denitrification could be a promising process for valorization of both GTR and nitrate-containing wastewater which in turn would support circular economy and sustainable development.

More and more Chinese families are using dishwashers, consumers have paid special attention to the sterilization and disinfection function of dishwashers in recent years. However, there is still a lack of research on the distribution of microorganisms in dishwashers nationwide in China. In order to better upgrade the sterilization and disinfection functions of dishwashers, the plate culture method and high-throughput sequencing technology were used to comprehensively analyze the microbiology of household dishwashers in different cities of China in spring, summer, autumn and winter in this study. A total of 1109 strains of bacteria were isolated from dishwashing machine samples by culturable method, including 706 strains of bacteria distributed in 72 genera, 403 strains of fungi distributed in 52 genera.The most frequently isolated bacteria were Bacillus, Pseudomonas, Brevibacillus, Exiguobacterium, and Acinetobacter. The most frequently isolated fungi were Aspergillus, Penicillium, Exophiala, Fusarium, and Candida. A total of 3779 OTUs were obtained from bacteria and 1541 OTUs were obtained from fungi by amplicon sequencing. The results of culture-independent analysis were consistent with those of culturable analysis. This study laid a foundation for the directional screening of superior microbial resources in dishwashers. It provided data support for the further upgrading of the sterilization and disinfection function of the dishwasher.

Anaerobic bioremediation is rarely an effective strategy to treat chlorinated ethenes such as trichloroethene (TCE) in acidic aquifers because partial dechlorination typically results in accumulation of daughter products. Methanotrophs have the capability of oxidizing TCE and other chlorinated volatile organic compounds (CVOCs) to non-toxic products, but their occurrence, diversity, and biodegradation capabilities in acidic environments are largely unknown. This study investigated the impacts of different methane (CH₄) concentrations and the presence of CVOCs on the community of acidophilic methanotrophs in microcosms prepared from acidic aquifer samples collected upgradient and downgradient of a mulch barrier installed to promote in-situ anaerobic CVOC biodegradation in Maryland, USA. The ability of indigenous methanotrophs to biodegrade CVOCs was also evaluated. Results of stable isotope probing (SIP) and Next Generation Sequencing (NGS) showed that the microbial communities in the microcosms varied by location and were affected by both CH₄ concentration and the presence of different CVOCs, many of which were biodegraded by the indigenous methanotrophs. Data indicate the likelihood of aerobic cometabolic degradation of CVOCs downgradient of the mulch barrier designed for anaerobic treatment. The study extends the overall knowledge of acidophilic methanotrophs in groundwater and shows that these bacteria have significant potential for degrading CVOCs even at low CH₄ concentrations.

Spills of petroleum or its derivatives in the environment lead to an enrichment of microorganisms able to degrade such compounds. The interactions taking place in such microbial communities are complex and poorly understood, since they depend on multiple factors, including diversity and metabolic potential of the microorganisms and a broad range of fluctuating environmental conditions. In our previous study, a complete characterization, based on high-throughput sequencing, was performed in a jet-fuel plume using soil samples and in in-situ microcosms amended with hydrocarbons and exposed for 120 days. Herein, we propose a metabolic model to describe the monoaromatic hydrocarbon degradation process that takes place in such jet-fuel-contaminated sites, by combining genome-centered analysis, functional predictions, and flux balance analysis (FBA). In total, twenty high/medium quality MAGs were recovered; three of them assigned to anaerobic bacteria (Thermincolales, Geobacter and Pelotomaculaceace) and one affiliated to the aerobic bacterium Acinetobacter radioresistens, potentially the main players of hydrocarbon degradation in jet-fuel plumes. Taxonomic assignment of the genes indicated that a putative new species of Geobacteria has the potential for anaerobic degradation pathway, while the Pelotomaculaceae and Thermincolales members probably act via syntrophy oxidizing acetate and hydrogen (fermentation products of oil degradation) via sulfate and/or nitrate reduction.

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The dairy industry is grappling with significant challenges in managing effluent due to environmental concerns and stringent regulatory demands, necessitating innovative solutions. The paper investigates how microbial engineering is transforming the treatment of dairy wastewater, offering advanced methods to minimize environmental impact and enhance sustainability. It delves into the current challenges faced by the dairy industry, such as regulatory compliance and the limitations of traditional treatment technologies, and introduces microbial engineering as a promising solution for effluent management. Microbial engineering leverages genetic engineering techniques and microorganisms to enhance the efficiency of treatment processes like bioaugmentation and bioremediation. The environmental and economic benefits of microbial engineering, highlighting its potential to reduce pollution and lower operational costs for the dairy industry. The specific figures can vary based on factors like farm size and location, studies suggest that microbial engineering can reduce wastewater pollution by up to 50% and nutrient runoff by 30%. It also identifies key challenges and there are still areas including strains for specific pollutants (drugs, hormones), enhance degradation pathways, and increase microbes’ stability (stress tolerance, long-term viability) that require further innovation to maximize its benefits. Through case studies and success stories, the paper demonstrates practical applications of microbial engineering in managing dairy effluent, illustrating how it can revolutionize industrial practices for a more sustainable future.

Pentachlorophenol (PCP) is a highly toxic and carcinogenic compound with significant environmental impact, necessitating effective treatment technologies. This study evaluates PCP removal mechanisms, including adsorption and biodegradation, during the startup of a horizontal-flow anaerobic immobilized biomass reactor (HAIB), and examines the impact of PCP concentration on microbial diversity using denaturing gradient gel electrophoresis (DGGE). The primary mechanism for PCP removal in the HAIB was adsorption, effectively described by the Freundlich isotherm model. Adsorption efficiency ranged from 86 to 104% for PCP concentrations between 0.2 and 5.0 mg/L, and 46% to 64% for concentrations between 0.098 and 0.05 mg/L. Additionally, PCP degradation intermediates such as 2,3-DCP and 2,6-DCP were detected, indicating that biodegradation also occurred in the HAIB. Organic matter degradation averaged 81 ± 9%, and methane content in the biogas averaged 46 ± 9%, confirming the anaerobic process. No inhibition of microbial activity was observed due to PCP toxicity, even at a PCP load of 5 mg PCP/g STV per day. While the archaeal community showed only slight changes, with similarity coefficients ranging from 88 to 95%, the bacterial community was significantly affected by PCP, with similarity coefficients ranging from 18 to 50%. Bacterial groups were responsible for the initial PCP degradation, while the archaeal community was involved in metabolizing the resulting byproducts. The use of indigenous inoculum from the Santos-São Vicente estuary demonstrated its potential for effective PCP removal. Polyurethane foam proved to be an effective support material, enhancing the adsorption process and reducing PCP toxicity to the microbial consortium. This study provides valuable insights into PCP adsorption and biodegradation mechanisms in HAIB, highlighting the effectiveness of indigenous inoculum and polyurethane foam for PCP removal.

Manganese is an essential trace element for humans, animals, and plants, but excessive amounts of manganese can cause serious harm to organisms. The biological manganese oxidation process mainly oxidizes Mn(II) through the secretion of unique manganese oxidase by manganese-oxidizing bacteria. The T1 Cu site of multicopper oxidase is the main site for substrate oxidation, and its role is to transfer electrons to TNC, where dioxygen reduction occurs. In this study, methionine (Met) No. 444 interacting with the T1Cu-coordinating amino acid in the multicopper oxidase CopA from Brevibacillus panacihumi MK-8 was mutated to phenylalanine (Phe) and leucine (Leu) by the enzyme. Based on the analysis of enzymatic properties and the structural model, the mutant protein M444F with 4.58 times the catalytic efficiency of the original protein CopA and the mutant protein M444L with 1.67 times the catalytic efficiency of the original protein CopA were obtained. The study showed that the manganese removal rate of the manganese-oxidizing engineered bacterium Rosetta-pET-copA^M444L cultured for 7 days was 88.87%, which was 10.77% higher than that of the original engineered bacterium. Overall, this study provides a possibility for the application of genetic engineering in the field of biological manganese removal.

The study evaluated the performance of thermophilic co-digestion in both single-stage methanogenic reactors (TMR) and two-stage systems, consisting of a thermophilic acidogenic reactor and a thermophilic sequential methanogenic reactor (TSMR). A 1:1 mixture of sugarcane vinasse and molasses was codigested in anaerobic fluidized bed reactors, with varying organic matter concentrations based on chemical oxygen demand (COD) ranging from 5 to 22.5 g COD L⁻¹. Both systems achieved high organic matter removal efficiency (51 to 86.5%) and similar methane (CH₄) yields (> 148 mL CH₄ g⁻¹COD_removed). However, at the highest substrate concentration (22.5 g COD L⁻¹), the TSMR outperformed the TMR in terms of energy generation potential (205.6 kJ d⁻¹ vs. 125 kJ d⁻¹). Phase separation in the two-stage system increased bioenergy generation by up to 43.5% at lower substrate concentrations (7.5 g COD L⁻¹), with hydrogen (H₂) generation playing a critical role in this enhancement. Additionally, the two-stage system produced value-added products, including ethanol (2.3 g L⁻¹), volatile organic acids (3.2 g lactate L⁻¹), and H₂ (0.6–2.7 L H₂ L⁻¹ d⁻¹). Microbial analysis revealed that Thermoanaerobacterium, Caldanaerobius, and Clostridium were dominant at 5 g COD L⁻¹, while Lactobacillus prevailed at concentrations of ≥ 15 g COD L⁻¹. The primary methane producers in the single-stage system were Methanosarcina, Methanoculleus, and Methanobacterium, whereas Methanothermobacter, Bathyarchaeia, and Methanosarcina dominated in the two-stage system.

Polyvinyl chloride (PVC) is the third most produced synthetic plastic and releases the most harmful and lethal environmental component after incineration and landfilling. Few studies on microbial degradation of PVC have been reported but very little knowledge about the enzymes. In the present study, esterase enzyme was isolated and partially purified from marine bacterial isolates (T-1.3, BP-4.3 and S-237 identified as Vibrio sp., Alteromonas sp., and Cobetia sp., respectively) having the capability of PVC degradation. Initially, a plate assay was carried out for testing esterase production by studying bacteria using 1-naphthyl acetate as substrate. Enzyme assay showed higher production of esterase i.e. 0.57 U mL⁻¹ (2nd day), 0.46 U mL⁻¹ (2nd day) and 0.55 U mL⁻¹ (5th day) by bacterial isolate Vibrio sp., Alteromonas sp. and Cobetia sp., respectively incubated with PVC. Other enzymes like lipase, laccase and manganese peroxidase were much less or negligible compared to esterase enzyme production. Sephadex G-50 column purification had shown 58.62, 42.35 and 223.70 units mg⁻¹ of a specific activity by esterase for bacterial isolates Vibrio sp., Alteromonas sp. and Cobetia sp., respectively. Further, Sephadex G-50 column purification removed all the contamination and gave a clear appearance of the band at 38, 20 and 20 KD for bacterial isolates Vibrio sp., Alteromonas sp., and Cobetia sp., respectively. Esterase has shown maximum stability at a range of pH between 6.0 to 7.5, temperature between 30 to 35 °C and salinity concentration between 3 to 3.5 M for all bacterial isolates. In conclusion, esterase enzyme has promising potential to degrade PVC which can contribute to the decline the plastic pollution in an eco-friendly manner from the environment.