Biodegradation最新文献

The synergistic effect of caffeic, jasmonic and salicylic acids and abscisic acid was highly effective in reducing the phytotoxic effect of Ni in isabgol plants by promoting growth, physiological processes and nutrient metabolism. This study was necessitated by the need to formulate an effective plan to make plants more tolerant to heavy metal-contaminated soil. The experiment was performed in a pot test using a completely randomized design with four replications. Nickel stress (100 mg/kg soil) significantly reduced root length (49.49%), shoot length (44.59%), root fresh weight (60.05%), shoot fresh weight (55.85%) and chlorophyll content (52.66%) compared to the unstressed control. The synergistic application of caffeic acid (1 mM), jasmonic acid (100 µM), salicylic acid (1 mM) and abscisic acid (50 µM) significantly mitigated these effects, increasing root length, shoot length by 21%1%, root fresh weight by 97%7% and shoot fresh weight by 59%9%, 21%1%, 97%7% and 45.31%, respectively, relative to the Ni-stressed control. This treatment also enhanced the activities of antioxidant enzymes, including superoxide dismutase (31.98%), peroxidase (46.24%), catalase (35.98%), ascorbate peroxidase (73.39%), glutathione peroxidase (62.94%) and glutathione reductase (64.76%), as well as non-enzymatic antioxidants such as ascorbic acid (48.57%), anthocyanins (64.40%), β-cyanin (27.83%), β-xanthin (42.13%), phenolic content (33.51%) and flavonoid content (38.70%). It also reduced Ni accumulation in roots, shoots and seeds by 33.72%, 36.31% and 49.69%, respectively, while improving the uptake of essential nutrients, such as Fe (30.66%), Mn (35.52%), Zn (32.98%) and N (14.99%). Photosynthetic efficiency, membrane stability and relative water content were also restored, leading to a 51.16% increase in seed yield. The synergistic interaction of these compounds enhances stress signaling, redox balance and metabolic regulation more effectively than their individual applications. Therefore, the combined exogenous application of caffeic acid, jasmonic acid, salicylic and abscisic acid is recommended as a sustainable strategy to improve Isabgol production in nickel-contaminated environments.

Anaerobic digestion (AD) is a widely used technology for treating organic waste and producing renewable energy; however, environmental stresses, such as heavy-metal contamination, can significantly affect its stability. This study examines the potential of an integrated anaerobic digestion-microbial electrolysis cell (AD-MEC) system to enhance process resilience to heavy-metal toxicity. The performance of the AD-MEC was evaluated using cadmium (Cd²⁺), copper (Cu²⁺), nickel (Ni²⁺), iron (Fe²⁺), chromium (Cr²⁺), and zinc (Zn²⁺), and compared with that of a conventional AD system. The AD-MEC system exhibited greater resistance to heavy-metal inhibition, achieving higher maximum chemical oxygen demand (COD) removal efficiency and methane content than the conventional AD system. The order of heavy-metal inhibition was Zn²⁺ > Cu²⁺ > Cr²⁺ > Ni²⁺ > Cd²⁺ > Fe²⁺ for the traditional AD and Cu² > Cr²⁺ for the AD-MEC. These results highlight the potential of bioelectrochemical integration to enhance the robustness of anaerobic digestion under heavy-metal stress.

Benzalkonium chloride (BAC) is a widely used quaternary ammonium compound whose persistence in wastewater systems raises concerns regarding its biodegradation and the associated microbial adaptive responses. This study examines the effect of carbon substrate composition on BAC biodegradation, microbial community structure, and antimicrobial susceptibility in semicontinuous activated sludge systems exposed to sub-inhibitory BAC concentrations. Reactors were operated using either a proteinaceous substrate (peptone) or a readily biodegradable substrate (acetate). Clear differences in the system's response were observed depending on the carbon source supplied. Peptone-fed systems sustained microbial activity and promoted effective BAC biodegradation, whereas acetate-fed systems exhibited pronounced toxicity, reduced biological activity, and negligible BAC removal. These contrasting behaviors were accompanied by marked shifts in microbial community diversity and composition. In parallel, exposure to BAC was associated to changes in antimicrobial susceptibility patterns, particularly affecting β-lactam antibiotics, that could be attributed to a substrate-dependent selective pressure. These results shows that carbon substrate composition may influence BAC biodegradation capacity and microbial adaptation in activated sludge systems. The findings contribute to a better understanding of the factors potentially controlling the biodegradation of quaternary ammonium compounds and highlight the important role of carbon availability in shaping microbial responses under BAC-associated selective stress.

Water pollution caused by dyes is a global problem. This study examines the effect of four recently created bacterial consortia on bioremediation of Reactive Blue 19 (RB 19, a recalcitrant, mutagenic, and carcinogenic anthraquinone dye) in a range of environmental and nutritional circumstances. Color reductions were significantly (P < 0.001) influenced by both the bacterial consortia and the factors tested. Under optimal conditions (Salt-optimized broth with 2% glycerol, 0.5% yeast extract, 2.5% NaCl, 75 mg/L dye, pH 8, 28 °C, 72 h incubation, and microaerophilic), 94.0, 96.7, 97.9, and 99.7% decolorization achieved by C1 (Pseudomonas fluorescens ENSG304, Klebsiella pneumoniae ENSG303, Acinetobacter lwoffii ENSG302, and Vitreoscilla sp. ENSG301), C2 (Enterobacter asburiae ENSD102, E. ludwigii ENSH201, and Escherichia coli ENSD101), C3 (ENSD102, ENSG301, and Bacillus thuringiensis ENSW401), and C4 (ENSD101, ENSH201, and ENSW401), respectively. Out of all consortia, C4 performed the best across all conditions, followed by C3. Under favorable conditions, these consortia generated high amounts of lignin peroxidase, laccase, and NADH-DCIP reductase, while enzyme expression was significantly repressed under unfavorable conditions. A remarkable amount of chemical oxygen demand (82.9 to 89.4%) and total organic carbon (66.4 to 71.6%) was decreased by inoculation of these consortia. The biodegradation of RB 19 was validated by Fourier Transform Infrared (FTIR) and UV-Vis spectrum studies. The biodegraded compounds did not inhibit plant and microbial growth, suggesting detoxification. These findings suggest that the studied consortia, particularly C4, exhibit promising potential for RB 19 decolorization under the tested conditions.

Environmental pollution caused by persistent organic pollutants poses a significant global threat due to their toxicity and tendency to accumulate in ecosystems. Microbial biodegradation offers a sustainable alternative to conventional remediation strategies. Among degradative microorganisms, the genus Ochrobactrum has gained attention for its metabolic versatility and ability to transform a wide range of xenobiotic compounds. This review comprehensively examines genus Ochrobactrum, focusing on its species diversity, pollutant-degrading capabilities, and the biochemical pathways underlying these transformations. The genetic basis for enzyme production involved in degradation is highlighted, and organic pollutants are categorized according to their chemical class with corresponding species, and reported degradation rates.

A novel strain of Paracoccus sp. QD-21, which is capable of simultaneous heterotrophic nitrification and aerobic denitrification, was isolated and investigated for the potential in removal of nitrogen in wastewater treatment. The strain exhibited nitrogen removal rates of 5.55, 3.35, and 2.78 mg/(L·h) for NH₄⁺-N (100 mg/L), NO₂^--N (100 mg/L), and NO₃^--N (100 mg/L), respectively. Notably, QD-21 maintained substantial nitrogen removal efficiency under high concentrations of inorganic nitrogen, highlighting its remarkable tolerance to complex nitrogenous conditions. Optimal nitrogen removal occurred with sodium succinate as carbon source, C/N 7:1, pH 8.41, 140 rpm, 38.41 °C, and inoculum size 4.56% (v/v). Analysis using molecular biology techniques revealed the presence of genes associated with the nitrification process, such as amo and hao, in QD-21. This confirms the nitrification pathway of strain: NH₄⁺-N → NH₂OH → NO₂^--N → NO₃^--N. Additionally, the presence of nirK, norB, and nosZ confirms the denitrification pathway in QD-21: NO₃^--N → NO₂^--N → NO → N₂O → N₂. Meanwhile, the presence of nirBD, nark, glnL, glnA, gltB, and nasA indicates that a portion of nitrogen is assimilated into biomass through the ammonia assimilation pathway, which supports cellular biosynthesis and growth at the expense of metabolic energy. Furthermore, in practical wastewater tests QD-21 achieved removal efficiencies of 75.5% for NH₄⁺-N and 55.8% for COD. Such findings demonstrate the great potential of strain QD-21 in treating nitrogen pollution from diverse sources.

The development of efficient systems for removing antibiotics from wastewater is being pushed by increase in antibiotic resistance brought on by the environmental discharge of antibiotics. Antibiotic were not completely eliminated using conventional technologies like activated sludge, constructed wetland systems and many other procedures. A viable alternative for treating wastewater through adsorption, accumulation, biodegradation, photodegradation, and hydrolysis has recently been investigated using microalgae-based technology. This review focuses on effects of antibiotics on microalgae, as well as the ways in which microalgae remove antibiotics and how they work with other technologies to do so, including photocatalysis, advanced oxidation, and complementary microorganism degradation. The physiochemical and operational parameters like pH, temperature, light intensity and many more which influence the elimination of antibiotics in the wastewater treatment system. Future research requirements, further opportunities, the limitations of the available microalgae-based technologies were also discussed.

In this study, exopolymeric substances (EPS) from Bacillus cereus were immobilized in alginate to form alginate-EPS beads. The surface characteristics of the alginate-EPS beads were examined using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). The mechanisms of Pb removal was determined based on equilibrium and kinetic models. Packed-bed biosorption studies using Pb solutions (750 mg L^-1 concentration) evaluated their efficacy for Pb uptake and removal, under the influence of initial pH of metal solution and the size of biosorbents. The reusability of the alginate-EPS beads was also tested by examining the column regeneration, exhaustion time and sorption-desorption activities of the Pb-loaded beads. Results revealed that the alginate-EPS beads produced have uneven surface with various functional groups (hydroxyl, amide, carboxyl, phosphates) detected. Their Pb removal efficacy was highest in Pb solutions with pH 4, recording 51.52% Pb removal, followed by pH 6 (48.62%) and pH 8 (46.78%). For bead size, alginate-EPS beads measuring 3 mm diameter size was more efficient in Pb removal (51.52%), compared to 2 mm- (39.23%) and 5 mm-sized beads (28.52%). All alginate-EPS beads complied with the Langmuir isotherm (R² = 0.992) and pseudo-second order kinetic (R² = 0.995), suggesting monolayer adsorption is likely to have occurred on their homogenous surface. The alginate-EPS beads were successfully used for five adsorption cycles, with consistent Pb removal (41.40-50.59%). This study recommends the use of 3 mm bead size for Pb removal (pH 4 solutions) due to greater Pb removal (51.5%) and uptake (13.29 mg g^-1), and reasonable exhaustion time (540 min). There is potential of applying alginate-EPS beads in packed-bed systems as a feasible and effective method for the removal of heavy metals from wastewater.

Emerging contaminants (ECs) are synthetic or naturally occurring chemicals that persist in aquatic and terrestrial environments and cause significant risks to ecosystems and human health. The review focuses on major classes of ECs, including pharmaceuticals, pesticides, industrial chemicals, microplastics, and heavy metals. It systematically examines microbial remediation strategies involving bacteria, fungi, and algae, emphasising their metabolic flexibility in biodegradation and detoxification mechanisms such as bioaugmentation, bio stimulation, and rhizoremediation. It also highlights recent advances in multi-omics technologies that uncover critical genes, metabolic pathways, and regulatory networks, enabling the engineering of microbial consortia for enhanced contaminant removal. The article provides a comprehensive synthesis of microbial taxa, mechanisms, and emerging biotechnological applications, offering novel insights into eco-friendly and sustainable solutions for the effective remediation of various emerging contaminants. The investigation stands out by explaining recent advances in microbial metabolic strategies combined with multi-omics insights for a holistic understanding and future directions in bioremediation of a wide spectrum of emerging environmental contaminants.

Rising microplastic (MP) pollution can significantly affect engineered treatment systems such as anaerobic digestion (AD). While prior studies have investigated the influence of individual polymers, varying concentrations and sizes on AD, the role of MP morphology and polymer interactions remains underexplored. This study investigated these factors using polyethylene terephthalate (PET) and polyamide 6 (PA6) MPs, both in isolation and in combination (1:1 ratio), introduced as microfibres (MFs) and fragments at three concentrations, 1, 5, and 15 mg/gTS. Results revealed morphology-dependent effects on methane production. MF exposure inhibited methane yield by 10-17% (p < 0.01), with PET and mixed polymers exhibiting a correlation to MP concentration. In contrast, fragments enhanced methane yield, particularly PA6 and mixed (PET and PA6) polymers increased methane output by 9 and 17% at the highest dose, respectively. Kinetic modelling further revealed that MFs consistently reduced methane production potential, apparent degradation and hydrolysis rate, whereas fragment trends were polymer-driven. Scanning electron microscopy (SEM) micrographs showed greater surface roughness in PA6, which enhanced microbial colonization compared to PET. Elevated reactive oxygen species (ROS) levels with MF addition, especially at the highest concentration, suggested higher oxidative stress and microbial inhibition. Microbial community analysis showed that exposure to MP fragments resulted in similar bacterial shifts across different polymer types, compared to the more diverse effects observed with MFs. Archaeal diversity was more affected by particle shape than polymer composition. All MP treatments favoured a shift toward hydrogenotrophic over aceticlastic methanogenesis. PET and mixed MF addition resulted in a substantial decline in the relative abundance of Actinobacteria (18-20%) from 42% in the control and other methanogenic taxa compared to their fragment counterparts. MF addition disrupted community structure, suppressed additive-degrading taxa, and increased acetogenic groups such as Synergistetes. Overall, the findings suggest that a comprehensive understanding of all influencing factors, including MP morphology, polymer type and concentrations, is important for effective AD system management.