Biodegradation最新文献

In the context of the circular economy, managing sewage sludge (SS) is vital for resource valorization and sustainability. This study aims to compare the impact of different application methods (two phase mulch, single phase mulch, incorporation) and doses (10, 25, 40 and 50 t/ha) of residual sewage sludge on the quality of sandy-silty soils and the morpho-physiological characteristics of durum wheat (Triticum durum) plants, specifically the Oued El Bared G4 variety. The field experiment was conducted in a hot arid region in northeastern Algeria. Results demonstrated that SS significantly improved soil fertility and wheat performance (p < 0.001). Soil organic matter (OM) and Phosphorus peaked at 1.92% (T2D3) and 258.46 ppm (T1D4) respectively, representing a substantial enrichment compared to lower doses. Regarding crop yield, the 1000 grain weight (WTG) reached a maximum of 54.88 g with single phase mulch (T2D1), which is 33.8% higher than the two phase application method. Similarly, plant height and leaf surface area (LSA) were maximized under the T2 method (91 cm and 37.41 cm², respectively). While soil pH remained stable, electrical conductivity (EC) increased with dosage, peaking at 1.87 µS/cm (T2D4). This finding suggest that sludge biorecycling in single phase mulch application (T2) at moderate doses optimizes both soil quality and durum wheat yield component in arid region. Future research should focus on the long term cumulative effects of repeated sludge application on soil heavy metal dynamics and groundwater quality in arid environment.

The aim of this study is to investigate the effect of magnetite (Fe₃O₄) addition on biogas and biomethane production in the anaerobic treatment of chicken manure (CM) and municipal organic solid waste (MOSW). Batch experiments were conducted under mesophilic conditions using different substrate-to-inoculum (S/I) ratios (0, 1, 2, and 4 g VS-S/g VS-I) and magnetite concentrations (50, 100, 200, 400, and 600 mg L⁻¹). The highest biogas and biomethane production was obtained in the S/I = 1 gVS-S/gVS-I, 2:1 (CM: MOSW) reactor and were 2910.5 ± 199.4 mL CH₄/gVS and 1718.03 ± 117.73 mL CH₄/gVS, respectively. At different magnetite concentrations, the highest biogas and biomethane production occurred at 200 mgL^-1 magnetite loading rate, 1842.7 ± 112.0 mL CH₄/gVS and 1081.99 ± 65.78 mL CH₄/gVS, respectively. The highest total organic carbon (TOC) and total nitrogen (TN) concentrations were determined at S/I = 4, 2:1 (CM: MOSW) gVS-S/gVS-I loading ratio, while the highest TS and VS removal efficiency was determined at S/I = 1 gVS-S/gVS-I, 2:1 (CM: MOSW) ratio and 100 mgL^-1 magnetite loading ratio. When the microbial distribution was examined, the first five dominant species (W5, S1, Coprothermobacter, Treponema and Fervidobacterium) did not change after the addition of magnetite. The findings demonstrate the positive effects of magnetite addition on biogas and biomethane production, providing significant insights for the development of new strategies to enhance anaerobic digestion processes.

Bile salts are conjugated steroids with digestive functions in vertebrates that reach the ecosystem upon excretion. Their environmental degradation by bacteria resembles the steroid nucleus catabolism that uses the 9,10-seco pathway, although there are two variants depending on whether the hydroxyl group at C-7 is eliminated (variant Δ^4,6) or not (variant Δ^1,4). Caenibius tardaugens, formerly known as Novosphingobium tardaugens, is a steroid-degrading bacterium used as a model to study the genetic and metabolic traits of steroidal sex-hormones catabolism. In this work, we investigated the bacterium ability to grow on bile salts such as cholate and deoxycholate and we performed directed mutagenesis along with transcriptomic analysis to shed light on the genes involved in bile salt metabolism. The mutation of the igr-like operon (EGO55_03105-EGO55_03125), similar to the cholesterol-degrading operon igr from Rhodococcus jostii RHA1, did not affect the ability to grow on bile salts. The transcriptomic analysis in the presence of cholate showed the induction of two gene clusters named bsd I (bile-salts degradation) (EGO55_16295 to EGO55_16335) and bsd II (EGO55_11460-EGO55_11480), containing genes that, according to their sequence identity to other bile salt-degrading bacteria, might participate in the side chain degradation and the HIP pathway of cholate catabolism, respectively. Moreover, the presence of other proteins homologous to the 7α-hydroxy steroid dehydratase Hsh2, such as EGO55_02245, EGO55_12965, or EGO55_06935, indicates that C. tardaugens cholate metabolism proceeds via the Δ^4,6 variant, as it is conserved in several bacteria from the genera Sphingobium, Novosphingobium, and Sphingomonas.

The escalating global plastic pollution crisis poses an unprecedented threat to ecosystems and human well-being. Plastic waste that has accumulated over decades remains undegraded and continuously leaches toxic additives and microplastics into the environment. Harnessing the metabolic diversity of microorganisms and their complex enzyme systems can be a sustainable, rapid and cost-effective alternative to conventional plastic waste management. Microbial enzymes that can cleave polymeric chains into valuable biochemicals or monomers opened an encouraging footing to provide a promising foundation for promoting a circular plastic economy. This review outlines the major milestones in enzymatic plastic biodegradation, emphasising the underlying mechanisms, enzyme discovery strategies, and existing challenges and opportunities in this emerging field. Particular focus is given to recent trends in computational, in silico, machine and AI-assisted enzyme discovery. Furthermore, we evaluated current literature on the enzymatic degradation of the most widely used commercial plastics, including polyethylene terephthalate, polyurethane, polyethylene, polystyrene, polypropylene, and polyvinyl chloride. The review ends with a critical analysis of the scope and challenges of the enzymatic degradation of plastics.

Since the discovery of anaerobic ammonium oxidation bacteria, commonly known as AnAOB in the early 1990s, more than a quarter century has passed and partial nitrification/anammox process for sewage treatment is still mainly in lab and pilot-scale research phase with few plants in operation. The main challenges for that are enrichment, grow and how to keep AnAOB in the reactor on low-strength wastewater treatment, such as in anaerobically treated domestic sewage. Another important aspect is need for continuous supply of nitrite and how to minimize nitrite consumption by others than anammox. In addition to that other minor control parameters play an important role, such as hydraulic and sludge retention time, dissolved oxygen, temperature, pH, etc. This paper presents a detailed review of essential process parameters and identifies gaps and solutions for effective implementation of the anammox process highlighting the different factors that suppress AnAOB growth, along with the aspects favouring activity and immobilization. Reactor start-up and operation, bacteria inhibition and conversion of emerging-pollutants is also investigated, with their effect on AnAOB and their removal. The main conclusions are the sustainability evaluation, which found that the process reduce the overall GHG emissions compared to conventional nitrogen removal processes; a possible microbial pathway that could be involved for simultaneous organics, nutrients and emerging-pollutants removal; and, finally, a novel concept of a three-stage treatment process in two up-flow anaerobic sludge blanket-based system is proposed.

Two independent experiments were performed to investigate role of NO in 5-aminolevulinic acid-mediated resistance to lead toxicity in barley plants. Lead toxicity significantly resulted in reduction of plant growth, Fv/Fm, total chlorophyll, leaf water potential, and Ca²⁺ as well as K⁺ potassium levels. Concurrently, it resulted in elevated levels of leaf MDA, H₂O₂, EL, Pb, and NO in comparison to control group. Both ALA (50 µM and 100 µM; ALA1 and ALA2) treatments enhanced plant growth parameters and elevated leaf K⁺ and Ca²⁺ levels, while simultaneously decreasing leaf Pb, H₂O₂, and MDA concentrations in comparison to Pb-stressed plants. A second experiment was conducted to ascertain involvement of nitric oxide in mitigation of Pb stress in barley seedlings by ALA, utilizing nitric oxide scavenger C₁₄H₁₆N₂O₄.K (cPTIO) in conjunction with ALA treatments. ALA-induced tolerance to Pb stress was entirely negated by administration of cPTIO (C₁₄H₁₆N₂O₄.K), which significantly decreased concentrations of endogenous nitric oxide. The findings indicated that ALA improved resistance of barley seedlings to Pb toxicity via activating endogenous nitric oxide. This was corroborated by elevation of H₂O₂ and MDA levels, with a reduction in SOD, CAT, and POD activities. The application of cPTIO along with ALA, led to growth inhibition and a notable increase in leaf Pb concentrations. Both ALA and nitric oxide collaboratively enhanced Pb tolerance in barley.