Search Results (259)

The growing threat of organic pollution to surface waters necessitates the development of rapid and scalable monitoring tools that transcend the limitations of the standard 5-day biochemical oxygen demand (BOD₅) test. This study presents a novel approach by developing a highly stable and rapid BOD biosensor based on the microorganism Paracoccus yeei, immobilized within a sol–gel-derived xerogel matrix synthesized on a polyhydroxybutyrate (PHB) substrate. The PHB-supported xerogel significantly enhanced microbial viability and sensor stability. This biosensor demonstrated a correlation (R² = 0.93) with the standard BOD₅ method across 53 diverse water samples from the Tula region, Russia, providing precise results in just 5 min. The second pillar of our methodology involved analyzing multi-year Landsat satellite imagery via the Global Surface Water Explorer to map hydrological changes and identify zones of potential anthropogenic impact. The synergy of rapid ground-truth biosensor measurements and remote sensing analysis enabled a comprehensive spatial assessment of water quality, successfully identifying and ranking pollution sources, with wastewater discharges and agro-industrial facilities constituting the most significant factors. This work underscores the high potential of PHB–xerogel composites as efficient immobilization matrices and establishes a powerful, scalable framework for regional environmental monitoring by integrating advanced biosensor technology with satellite observation. Full article

Arsenic (As) toxicity drives the evolution of resistance mechanisms in environmental microorganisms. Bacteria of the Bacillus genus are frequently identified in isolates from arsenic-contaminated sites, highlighting the importance of understanding the molecular mechanisms related to this bacterial genus. Bacillus subtilis, a soil microorganism and Gram-positive model paradigm, employs multiple strategies to counteract As toxicity, including biosorption, redox transformation, active efflux, and inducible genetic regulation. This review provides a comprehensive analysis of the physiological and molecular mechanisms involved in arsenic response in B. subtilis and related species, focusing on the ars and ase operons. The ars operon, located within the mobile SKIN element, encodes a reductase (ArsC), an Acr3-type efflux pump (ArsB), a carbon–arsenic lyase (ArsI/YqcK), and a transcriptional repressor (ArsR), all co-regulated in response to arsenic. In turn, the ase operon contributes to resistance via an ArsB-type efflux system (AseA) and its own regulatory protein (AseR) but lacks an arsenate reductase. Additionally, genes such as aioAB, arrAB, and arsD are discussed, along with evidence for extracellular detoxification and cell surface immobilization of As. Studies on environmental Bacillus species are examined, pointing out the evolutionary implications of As resistance and the biotechnological potential for remediation of contaminated sites. Full article

β-glucosidase is a kind of enzyme that can hydrolyze β-glucosidase bonds, and it plays a key role in many fields, such as lignocellulose degradation and wine brewing. The global β-glucosidase market is currently estimated to be USD 40 billion, and more is expected in the future. This trend is mainly due to the demand for enzymes in biofuel processing. At present, β-glucosidase is mainly derived from microorganisms, animals, plants and so on. It has received great attention due to its ease of production, catalytic efficiency and versatility, which have promoted its biotechnology potential in different industries. With the increasing demand for β-glucosidases, various cost-effective methods are being explored to discover, redesign and enhance their production and functional properties. Therefore, this paper reviews the latest progress in the application of β-glucosidase in industry. In this regard, the focus is on the use of recombinant technology, protein engineering and immobilization technology to improve the industrial applicability of the enzyme. In addition, the application status of β-glucosidase in production and life was analyzed. Full article

This work was undertaken in order to identify the presence of changes in the characteristics of poly(vinyl alcohol) (PVA) cryogels that can contribute to the degradation of such polymer matrices under the influence of their contact with various microorganisms used in immobilized form in different biotechnological processes using various complex media and conditions. Immobilized cells of bacteria, yeasts, microalgae, fungi, and microbial consortia were involved in the investigations. It was established that the presence of microorganisms can indirectly (through media transformed by them, in particular, containing lipids) or directly (through high rates of metabolite production, in particular, the fast accumulation of gases in the pores of polymer matrices, or due to the colonization of cryogels (self)immobilization by fungi with the growing mycelium) decrease rheological characteristics of PVA cryogel. Such weakening of PVA cryogels can be expected as a result of the first stage of further degradation of polymer matrices. The values of both the modulus of elasticity and the shear modulus of PVA cryogels confirmed this. The effect of high pressure accumulated in the reactors with PVA cryogel-immobilized cells, as well as their use in flow systems, was not revealed. These factors can be taken into account for the sustainable use of matrices based on PVA cryogels as biocatalysts with microorganisms or soil-structuring elements in artificial or natural environments. Full article

While root exudates play a crucial role in maintaining ecosystem balance and promoting plant growth, existing research primarily focuses on single ecosystems (e.g., field crops), with systematic investigations of their ecological functions in compound cropping systems, particularly nitrogen (N) cycling mechanisms in orchard multi-cropping systems, remaining limited. This review focuses on the N impact mechanisms mediated by plant root exudates in orchard ecosystems, emphasizing how root exudates optimize soil N activation, absorption, and utilization efficiency by modulating rhizosphere processes (e.g., nitrogen mineralization, root architecture remodeling). Studies indicate that the changes in orchard ecosystem function mediated by organic acids and flavonoids root exudates can significantly reduce nitrogen loss risks and increase the soil nitrogen turnover rate by lowering pH-activated nutrients, balancing the C:N ratio, and immobilizing microbial communities. This process also involves the coordinated regulation of nitrification, denitrification, and microbial fixation. Future research should prioritize investigating the interaction networks and regulatory mechanisms between root exudates of associated orchard crops and N-fixing microorganisms. This research direction will provide a scientific basis for improving the N use efficiency in orchard crops, optimizing fertilizer reduction techniques, and reducing chemical fertilizer usage, providing significant implications for achieving sustainable agricultural development. The theoretical support offers important scientific and practical value for advancing green and sustainable agriculture. Full article

Microbially induced carbonate precipitation (MICP), as an eco-friendly biomineralization technology, has opened up an innovative path for the green and low-carbon development of the mining industry. Unlike conventional methods, its in situ solidification minimizes environmental disturbances and reduces carbon emissions during construction. This article reviews the research on MICP technology in various scenarios within the mining industry, summarizes the key factors influencing the application of MICP, and proposes a future research direction to fill the gap of the lack of systematic guidance for the application of MICP in this field. Specifically, it elaborates on the solidification mechanism of MICP and its current application in the solidification and storage of tailings, heavy metal immobilization, waste resource utilization, carbon sequestration, and field-scale deployment, establishing a technical foundation for broader implementation in the mining sector. Key influencing factors that affect the solidification effect of MICP are discussed, along with critical engineering challenges such as the attenuation of microbial activity and the low uniformity of calcium carbonate precipitation under extreme conditions. Proposed solutions include environmentally responsive self-healing technologies (the stimulus-responsive properties of the carriers extend the survival window of microorganisms), a one-phase low-pH injection method (when the pH = 5, the delay time for CaCO₃ to appear is 1.5 h), and the incorporation of auxiliary additives (the auxiliary additives provided more adsorption sites for microorganisms). Future research should focus on in situ real-time monitoring of systems integrated with deep learning, systematic mineralization evaluation standard system, and urea-free mineralization pathways under special conditions. Through interdisciplinary collaboration, MICP offers significant potential for integrated scientific and engineering solutions in mine waste solidification and sustainable resource utilization. Full article

Iron, an essential element for virtually all known organisms, serves not only as a micronutrient but also as an energy source for bacteria. Iron-oxidizing microorganisms mediate Fe(II) oxidation under diverse redox conditions, yielding amorphous iron (hydr)oxides or crystalline iron minerals. This globally significant biogeochemical process drives modern iron cycling across terrestrial and aquatic ecosystems. The resulting biomineralization not only produces secondary minerals but also effectively immobilizes heavy metals, offering a sustainable strategy for environmental remediation. This review systematically examines (1) the biogeochemical mechanisms and mineralogical signatures of Fe(II) oxidation by four distinct iron oxidizers: acidophilic aerobes (e.g., Acidithiobacillus), neutrophilic microaerophiles (e.g., Gallionella), nitrate-reducing anaerobes (e.g., Acidovorax), and anoxygenic phototrophs (e.g., Rhodobacter); (2) research advances in heavy metal immobilization by biogenic iron minerals: adsorption, coprecipitation, and structural incorporation; and (3) the impact of pH, temperature, organic matter, and coexisting ions on Fe(II) oxidation efficiency and iron mineral formation by iron-oxidizing bacteria. By characterizing iron-oxidizing bacterial species and their functional processes under varying pH and redox conditions, this study provides critical insights into microbial behaviors driving the evolution of acid mine drainage (AMD). Full article

Soil microbes are important for maintaining agricultural ecosystems by promoting nutrient cycling, plant growth, and soil resilience. Microbial-based inoculants, such as bio-inoculants and bioremediation agents, have been identified as suitable means to promote soil health, reduce environmental deterioration, and achieve sustainable agriculture. Bio-inoculants, such as biofertilizers and biopesticides, promote nutrient availability, plant growth, and chemical input dependency reduction. Diverse microbial populations, especially plant growth-promoting bacteria (PGPB), enhance resistance by promoting a symbiotic association with plants and inducing natural resistance against insects. Bioremediation, the second significant microbial intervention, is the use of microorganisms for detoxifying and rehabilitating polluted soils. Methods effectively degrade organic pollutants, immobilize heavy metals, and mitigate the toxic effects of industrial and agricultural pollutants. Recent advances in microbial ecology and biotechnology, such as metagenomics, have transformed the knowledge of microbial soil communities, and tailor-made microbial formulations and monitoring equipment may be developed to maximize their activity. Though promising, environmental heterogeneity, scalability, and lack of field-based evidence constrain their widespread application. Multidimensional applications of microbial solutions in agroecology are explored in this review, with a focus on their potential in maintaining soil health, crop production, and environmental sustainability. It also addresses the application of bioremediation and microbial inoculants in agroecosystems and technological innovations with future research objectives. Microbial innovation to shape the soil microbiome offers a valid tool for addressing global challenges in agriculture, food security, and ecological resilience in the context of climate change. Full article

The bioavailability of heavy metals is profoundly influenced by their interactions with active soil components (microorganisms, organic matter, and iron minerals). However, the effects of urease-producing bacteria combined with organo-Fe hydroxide coprecipitates (OFCs) on Cd accumulation in wheat, as well as the mechanisms underlying these effects, remain unclear. In this study, pot experiments integrated with high-throughput sequencing were employed to investigate the impacts of the urease-producing bacterial strain TJ6, ferrihydrite (Fh), and OFCs on Cd enrichment in wheat grains, alongside the underlying soil–microbial mechanisms. The results demonstrate that the strain TJ6-Fh/OFC consortium significantly (p < 0.05) reduced (50.1–66.7%) the bioavailable Cd content in rhizosphere soil while increasing residual Cd fractions, thereby decreasing (77.4%) Cd accumulation in grains. The combined amendments elevated rhizosphere pH (7.35), iron oxide content, and electrical conductivity while reducing (14.5–21.1%) dissolved organic carbon levels. These changes enhanced soil-colloid-mediated Cd immobilization and reduced Cd mobility. Notably, the NH₄⁺ content and NH₄⁺/NO₃⁻ ratio were significantly (p < 0.05) increased, attributed to the ureolytic activity of TJ6, which concurrently alkalinized the soil and inhibited Cd uptake via competitive ion channel interactions. Furthermore, the relative abundance of functional bacterial taxa (Proteobacteria, Gemmatimonadota, Enterobacter, Rhodanobacter, Massilia, Nocardioides, and Arthrobacter) was markedly increased in the rhizosphere soil. These microbes exhibited enhanced abilities to produce extracellular polymeric substances, induce phosphate precipitation, facilitate biosorption, and promote nutrient (C/N) cycling, synergizing with the amendments to immobilize Cd. This study for the first time analyzed the effect and soil science mechanism of urease-producing bacteria combined with OFCs in blocking wheat’s absorption of Cd. Moreover, this study provides foundational insights and a practical framework for the remediation of Cd-contaminated wheat fields through microbial–organic–mineral collaborative strategies. Full article

Metals are natural components of the lithosphere, whose amounts and bioavailability are increasing in many areas due to their continuous release from both natural sources and intensive human activities. Some metals are essential or beneficial for living organisms, while others are non-essential and potentially toxic. When present at higher concentrations, even essential and beneficial metal ions can become harmful to all forms of life. Bacteria, unicellular organisms that have been exposed to metals since the earliest stages of life on Earth, have evolved metabolic pathways involving essential metals as well as diverse strategies to cope with metal toxicity. In the domain Bacteria, two main strategies have been identified: (i) metal exclusion, which includes cell wall sequestration and immobilization of metals in extracellular exopolysaccharides, siderophores, and other soluble microbial products, as well as (ii) metal tolerance, involving intracellular sequestration of metals (e.g., by metallothioneins, or low molecular weight thiols) as well as enzymatic conversion of metals to less toxic forms and/or its active efflux. Microorganisms possessing such adaptive traits are considered valuable agents for potential application in medicine, environmental sciences, and bioengineering (e.g., bioremediation and/or biomining). Full article

This study presents a microbial sensing device that employs a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) matrix to immobilize viable and metabolically Escherichia coli cells. This device enables the monitoring of microorganism metabolic activity in response to external stimuli such as variations in carbon sources or exposure to inhibitory or toxic compounds. PEDOT:PSS, a conductive and chemically stable polymer, was electrodeposited onto screen-printed electrodes, successfully entrapping approximately 1.26 × 10⁷ cells per electrode. The confocal microscopy of Live/Dead-stained samples confirmed a uniform cell distribution and an average viability of ~78%. Ferricyanide respirometry validated the metabolic activity of the immobilized cells. The biosensor’s performance was evaluated using 3,5-dichlorophenol (3,5-DCP) as a reference toxicant. The observed inhibition of microbial activity correlated with 3,5-DCP concentration, yielding a half-maximal effective concentration (EC₅₀) of 9 ppm, consistent with the literature values. Full article

Arsenic (As) and cadmium (Cd) contamination in groundwater poses significant risks to human health and environmental sustainability. Iron–manganese minerals and associated microorganisms in subsurface environments exhibit remarkable potential for immobilizing and transforming toxic metal(loid)s through adsorption, redox reactions, and co-precipitation. This study integrates bibliometric analysis with mechanistic review strategies to systematically evaluate the roles of iron–manganese biomineralization in As/Cd stabilization. Bibliometric insights identify emerging research trends, including the application of biogenic oxides and microbial redox cycles in groundwater remediation. Mechanistic analysis reveals how microbial–mineral interactions regulate As/Cd sequestration, emphasizing the influence of environmental factors such as pH, redox conditions, and microbial metabolic pathways. Case studies demonstrate the viability of in situ remediation technologies leveraging these biogeochemical processes, though challenges persist in achieving consistent field-scale performance and long-term stability. Future efforts should prioritize optimizing microbial consortia, advancing real-time monitoring systems, and integrating biogeochemical strategies with engineered barriers. By synthesizing quantitative trends and mechanistic principles, this work provides actionable frameworks for enhancing natural attenuation and designing sustainable remediation systems for metal-contaminated groundwater. Full article

To enhance the resistance of stainless steel (SS) against biofouling and biocorrosion, hyperbranched poly(viologen) brushes were covalently immobilized onto SS substrates. This study systematically evaluated the efficacy of the functionalized SS substrates in inhibiting microorganism adhesion, biofouling and biocorrosion. Enhanced antifouling and antimicrobial properties were evidenced through assays involving the attachment of Amphora coffeaeformis, the settlement of Pseudomonas sp. bacteria and barnacle cyprids. Furthermore, the functionalized SS substrates demonstrated superior antifouling performance alongside excellent biocorrosion–inhibition properties. These findings suggest that the functionalized SS substrates, with their robust antimicrobial, antifouling and anticorrosion capabilities, hold significant potential for applications in aquatic environments Full article

The changes in soil nitrogen mineralization rate induced by litter input can determine the availability of nitrogen for plant growth in the soil. In forest ecosystems, the mixing of different species of litter can alter the chemical properties of the litter, ultimately affecting the rates of soil nitrogen transformation and cycling. In this study, litters with Fraxinus mandshurica Rupr. and Larix gmelinii (Rupr.) Kuzen. and mixed litter with Fraxinus mandshurica and Larix gmelinii were added to dark brown soil and incubated in the lab for 175 days at 25 °C. NH₄⁺-N and NO₃⁻-N contents and nitrogen mineralization rates were periodically measured to explore the effect of mixed litter addition on soil nitrogen mineralization. The results showed that compared to Larix gmelinii litter, Fraxinus mandshurica litter demonstrates higher carbon, nitrogen, and phosphorus contents while exhibiting lower lignin and cellulose contents and lower C/N and lignin/N ratios. Soil inorganic nitrogen content showed a trend of initial decrease followed by an increase. At the end of the incubation, soil NH₄⁺-N and NO₃⁻-N and the total inorganic nitrogen contents were 4.6–7.8 times, 2.2–3.4 times, and 2.9–4.3 times higher than the initial value, respectively. The soil nitrogen mineralization rate exhibited an initial rapid increase followed by stabilization. During days 7–28 of incubation, the nitrogen mineralization rates in litter addition treatments were lower than that in the control, while they were higher than that in the control during days 42–175. The soil nitrogen mineralization rate in the treatments with Fraxinus mandshurica litter and mixed litter were higher than those in the treatment with Larix gmelinii litter. The cumulative net nitrogen mineralization amounts in the Fraxinus mandshurica litter and mixed litter treatments were higher than those in the Larix gmelinii litter treatment, being 1.5 and 1.2 times those of the Larix gmelinii litter treatment, respectively. MBC and MBN presented a trend of first increasing and then decreasing, peaking on days 7 and 14 of incubation, respectively. Correlation analysis revealed that soil inorganic nitrogen content and nitrogen mineralization rate were positively correlated with the litter total nitrogen and soil microbial carbon and nitrogen and negatively correlated with litter C/N and lignin/N. The changes in soil inorganic nitrogen and nitrogen mineralization are primarily associated with soil microbial immobilization. Initially, in the treatments with litter addition, an increase in microbial biomass enhanced the immobilization of soil inorganic nitrogen. Subsequently, as litter mineralization progressed, the amount of litter decreased, leading to reduced microbial biomass and weakened immobilization. This study indicates that the interaction between litter types and soil microorganisms is the key factor affecting soil nitrogen mineralization process and soil mineral nitrogen content. These findings provide a scientific basis for soil fertility management in the forest ecosystems of Northeast China. Full article

Aerobic denitrifying microorganisms, with their strong environmental adaptability, low dissolved oxygen concentration requirements, rapid growth rate, and high nitrogen removal efficiency, significantly compensate for the shortcomings of traditional aerobic chemolithoautotrophic nitrification and anaerobic heterotrophic denitrification models. The introduction of aerobic denitrifiers can effectively enhance the removal of nitrate nitrogen. However, directly inoculating aerobic denitrifiers into wastewater leads to issues such as easy loss of bacterial cells and difficulty in forming a dominant flora, thus preventing the long-term maintenance of their enhancing effect on denitrification performance. To address this problem, microbial immobilization technology has been introduced into the remediation process of nitrogen-polluted water bodies. This technology can maintain a high biomass concentration, provide a stable breeding ground for microorganisms, and effectively prevent the rapid loss of microorganisms. This article systematically reviews the current status of the isolation of aerobic denitrifying bacteria, key enzymes, and genes, as well as the application progress of aerobic denitrifying bacteria and their immobilization technology, aiming to provide solid theoretical support for the practical application of aerobic denitrification technology and promote its further development in the field of nitrogen pollution control. Full article