Search Results (2,676)

Nitrate leaching from agricultural soils is a major contributor to groundwater contamination and non-point source pollution. Controlling this loss remains challenging due to the complexity of soil–water–nutrient interactions under intensive farming practices. Biochar, a porous, carbon-rich material derived from biomass pyrolysis, has emerged as a promising amendment for nitrate mitigation. This review summarizes recent advances in understanding the roles of biochar in nitrate retention and transformation in soils, including both direct mechanisms—such as surface adsorption, ion exchange, and pore entrapment—and indirect mechanisms—such as enhanced microbial activity, soil structure improvement, and root system development. Field and laboratory evidence shows that biochar can reduce NO₃⁻-N leaching by 15–70%, depending on its properties, soil conditions, and application context. However, inconsistencies in performance due to differences in biochar types, soil conditions, and environmental factors remain a major barrier to widespread adoption. This review also suggests current knowledge gaps and research needs, including long-term field validation, biochar material optimization, and integration of biochar into precision nutrient management. Overall, biochar presents a multifunctional strategy for reducing nitrate leaching and promoting sustainable nitrogen management in agroecosystems. Full article

Microplastic pollution has become a critical environmental issue, affecting terrestrial, freshwater, and marine ecosystems. These pollutants, originating from plastic degradation and primary sources, can act as carriers for harmful substances such as heavy metals and organic contaminants. While mitigation efforts are still in development, biological systems, particularly Black Soldier Fly Larvae (BSFL), have shown promise in organic waste management and pollutant bioaccumulation. Recent research explores the potential of BSFL to interact with and degrade microplastic particles, although the mechanisms remain underexplored. The role of microbial communities in facilitating microplastic degradation is of growing interest, as well as the impact of microplastic ingestion on the larvae’s efficiency in organic waste breakdown. However, experimental inconsistencies and environmental variations continue to delay progress, underscoring the need for further study to optimize bioremediation strategies and assess long-term ecological effects. This systematic review aims to explore the interactions between microplastics and BSFL, focusing on their potential as a bioremediation agent. It investigates the larvae’s ability to reduce microplastic pollution through bioaccumulation and degradation processes. Full article

The widespread use of masks in the community was occasioned by the COVID-19 global pandemic. This study examined bacterial contamination on surgical and face masks used in Githurai Market during daily activities, focusing on the sources, accumulation, and antibiotic resistance of bacteria. Sixteen respondents were selected to wear masks, from which bacteria were isolated from the inside and outside surfaces, as well as from swabs of their nose, mouth, and skin. The bacterial load was monitored at intervals of 0 h, 2 h, 4 h, and 6 h using culture-dependent methods. The identified bacteria included Staphylococcus, Klebsiella, Stenotrophomonas, Enterococcus, and Bacillus, amongst others sourced from the users’ mouth, skin, nose, and the environment. Bacterial accumulation increased with time, peaking at 6 h of mask use. Most of the bacteria isolates showed multidrug resistance to commonly used antibiotics including cefotaxime, streptomycin, and amoxicillin. This raises concerns about potential role of masks as reservoirs for pathogenic and antibiotic-resistant bacteria. The study emphasizes the need for better mask hygiene practices to reduce microbial contamination and the risk of spreading antibiotic-resistant bacteria. It also highlights the importance of developing strategies to address these risks and ensure the continued effectiveness of masks as a part of public health measures Full article

Acid- and heat-tolerant industrial microbial strains are crucial for biotechnological production because they minimize the risk of microbial contamination and reduce energy consumption associated with cooling requirements. Here, adaptive laboratory evolution (ALE) of Aurantiochytrium limacinum was performed to improve the capability of the strain to produce docosahexaenoic acid (DHA) under acidic and high-temperature conditions. A stepwise increase from 30 to 38 °C was applied during cultivation at pH 4.5. After 30 cycles of high-temperature exposure (34 °C), an adaptive strain (BBF002) was obtained. Cell growth and DHA production of BBF002 were higher than those of the parental strain (BBF001) by 32.95 and 7.12%, respectively, at pH 4.5 and 30 °C. Based on the experimental data obtained using glucose as a carbon source, a kinetic model was developed to describe cell growth, biomass maintenance, and DHA, and we used other metabolite methods to produce the native, parental, and adaptive strains. The growth traits of the three strains could be adequately described through logistic modeling. DHA was found to be a mixed-growth product produced during exponential and stationary phases, according to the Luedeking–Piret equation. Full article

Biosorbents are materials of biological origin (microbial, biomass-derived waste, or industrial by-products) used to adsorb or absorb pollutants. They have been used to remove various contaminants, including heavy metals, dyes, and pharmaceuticals. Their effectiveness is due to the different functional groups that interact with pollutants, including hydroxyl, amino, carboxyl, and phosphate groups. This review explores the various kinds of biosorbents (classification), mechanisms, and factors influencing biosorption, such as biomass content, time, temperature, pH, and concentration of pollutants, synthesis methods of biosorbents, and the current state of research on biosorbents. The review highlights the advantages of biosorbents, along with the challenges encountered, such as difficulty in regeneration and variability in performance. Finally, the review identifies research gaps and future directions, including exploration of modified/synthetic biosorbents for the removal of multi-component pollutants. Full article

Understanding the spatiotemporal dynamics of water quality parameters and microbial communities in drinking water distribution systems (DWDS) and their interrelationships is critical for ensuring the safety of tap water supply. This study investigated the diurnal, monthly, and annual variation patterns of water quality and the stage-specific succession behaviors of microbial communities in a DWDS located in southeastern China. Results indicated that hydraulic shear stress during peak usage periods drove biofilm detachment and particle resuspension. This process led to significant diurnal fluctuations in total cell counts (TCC) and metal ions, with coefficients of variation ranging from 0.44 to 1.89. Monthly analyses revealed the synergistic risks of disinfection by-products (e.g., 24.5 μg/L of trichloromethane) under conditions of low chlorine residual (<0.2 mg/L) and high organic loading. Annual trends suggested seasonal coupling: winter pH reductions correlated with organic acid accumulation, while summer microbial blooms associated with chlorine decay and temperature increase. Nonlinear interactions indicated weakened metal–organic complexation but enhanced turbidity–sulfate adsorption, suggesting altered contaminant mobility in pipe scales. Microbial analysis demonstrated persistent dominance of oligotrophic Phreatobacter and prevalence of Pseudomonas in biofilms, highlighting hydrodynamic conditions, nutrient availability, and disinfection pressure as key drivers of community succession. These findings reveal DWDS complexity and inform targeted operational and microbial risk control strategies. Full article

Aerobic granules are dense three-dimensional microbial aggregates which are known for their excellent settling ability, high biomass retention, and simultaneous biological reaction due to their multilayered structure. All these features enable the aerobic granules to remove emerging contaminants, such as pharmaceutical and personal care products (PPCPs), endocrine-disrupting compounds (EDCs), microplastics, and per- and polyfluoroalkyl substances (PFASs) in municipal and industrial wastewater. This review discusses the development and application of the aerobic granules, especially in a sequencing batch reactor (SBR) with a height over diameter (H/D) ratio of 5 to 10. The mechanisms of EC removal in aerobic granules and the removal efficiency of the ECs by aerobic granules were also scrutinized, with the reported removal efficiency ranging from 10–100% for PPCPs, 84–94% for EDCs, 74–95% for microplastics, and more than 85% for PFAs. In spite of the huge potential of aerobic granular technology, its large-scale implementation is hampered by operational and scaling challenges. Future research should focus on optimizing the operational parameters and overcoming the scale-up barrier to fully leverage the potential of aerobic granules in removing ECs. Full article

Legacy sulfur smelting has left behind complex contamination landscapes, yet the spatial structuring of microbial risks and adaptation strategies across soil profiles remains insufficiently understood. Microbial risk genes, including those conferring resistance to antibiotic resistance (ARGs), biocide and metal resistance (BRGs/MRGs), and virulence (VFGs), are increasingly recognized as co-selected under heavy metal stress, posing both ecological and public health concerns. In this study, we integrated geochemical analyses with metagenomic sequencing and functional annotation to jointly characterize the vertical (0–7 m) and horizontal (~2 km) distribution of heavy metals/metalloids, microbial communities, and functional risk genes at a historic smelting site in Zhenxiong, Yunnan. Heavy metals and metalloids such as arsenic (As), chromium (Cr), copper (Cu), and lead (Pb) showed clear accumulation with depth, while significantly lower concentrations were observed in both upstream and downstream locations, revealing persistent vertical and horizontal pollution gradients. Correspondingly, resistance and virulence genes were co-enriched at contaminated sites, suggesting potential co-selection under prolonged stress. LEfSe analysis revealed distinct ecological patterns: vertically, upper layers were dominated by nutrient-cycling and mildly stress-tolerant taxa, while deeper layers favored metal-resistant, oligotrophic, and potentially pathogenic microorganisms; horizontally, beneficial and diverse microbes characterized low-contamination zones, whereas heavily polluted areas were dominated by resistant and stress-adapted genera. These findings provide new insights into microbial resilience and ecological risk under long-term smelting stress. Full article

Background: Prosthetic candidiasis remains a significant clinical challenge, particularly due to the ability of Candida species to form resilient biofilms on dental prostheses, which limits the efficacy of conventional antifungal treatments. In this context, developing strategies to prevent or reduce biofilm formation is essential. Objectives This study investigates the antifungal and antibiofilm potential of a hydrogel formulation incorporating aminochalcone AM-35 as a candidate for the prevention and treatment of prosthetic candidiasis. Methods: To achieve this, experiments were conducted to determine the minimum inhibitory concentration (MIC) of aminochalcone AM-35 against Candida albicans and Candida tropicalis strains. AM-35 was incorporated into a hydrogel, which was subsequently tested on biofilms formed by these yeast species, both individually and in combination. The experimental disks were sterilized and incubated with C. albicans, C. tropicalis, and a mixture of both strains for 120 h to allow biofilm maturation. After contamination, the samples were divided into four experimental groups: Group 1: Hydrogel; Group 2: Hydrogel+AM-35; Group 3: Sodium hypochlorite (positive control); and Group 4: No treatment. The samples were then subjected to a sonication process to disaggregate the cells, which were then cultured on plates for colony-forming unit (CFU/mL) counts. The hydrogel’s toxicity was evaluated in vivo using the Galleria mellonella model. Results: The hydrogel formulation demonstrated significant antimicrobial activity, with an MIC of 7.8 μg/mL for C. albicans and 3.9 μg/mL for C. tropicalis. Treatment with the hydrogel at a concentration of 39 μg/mL resulted in a significant reduction in the formation and viability of mixed-species biofilms (p < 0.05). Additionally, the results indicated robust activity against C. albicans and C. tropicalis without presenting toxicity in the Galleria mellonella model. In conclusion, the hydrogel formulation exhibited effective antibiofilm activity, significantly reducing the microbial load. Conclusions: These findings open new possibilities for the development of alternative treatments for prosthetic candidiasis. The research suggests that the use of chalcone-based compounds may represent a promising approach in combating fungal infections in dentistry. Full article

Spirulina (Arthrospira platensis) is globally recognized for its high nutritional value and potential as a sustainable food source. However, the influence of targeted nutrient supplementation on its biochemical composition and microbial safety under tropical open-pond conditions remains underexplored, particularly in sub-Saharan Africa. This study evaluated the effects of three nutrient supplementation regimes (compositions A, B, and C) and a control on Spirulina cultivated over 30 days in raceway ponds at the Nomayos Spirulina Production Farm in Cameroon. All treatments maintained physicochemical parameters within ranges favorable for Spirulina growth. Composition A significantly enhanced protein content (60.38 ± 0.68%), while composition C promoted carbohydrate accumulation (28.02 ± 0.41%). Microbial assessments revealed variable contamination levels, with composition B exhibiting the highest Escherichia coli (1.05 ± 0.075 × 10⁵ CFU/g) and Salmonella/Shigella (4.09 ± 1.81 × 10⁵ CFU/g) counts, potentially due to nutrient-induced changes or post-harvest handling factors. Correlation analyses revealed a moderate positive relationship between nitrogen input and protein synthesis (r = 0.309), which was not statistically significant (p = 0.329). Additionally, higher pH was significantly correlated with total mesophilic counts (r = 0.661, p = 0.019) and E. coli (r = 0.655, p = 0.020). These findings highlight the importance of nutrient formulation and environmental management in improving nutritional quality while minimizing microbial risks during Spirulina cultivation in tropical, low-tech settings. Full article

Growing global concerns over pesticide residues and microbial contamination in plant-derived foods have intensified the demand for sustainable decontamination solutions. Conventional physical, chemical, and biological methods are hampered by inherent limitations, including operational inefficiency, secondary pollution risks, and nutritional degradation. Atmospheric cold plasma (ACP) has emerged as a promising non-thermal technology to address these challenges at near-ambient temperatures, leveraging the generation of highly reactive oxygen/nitrogen species (RONS), ultraviolet radiation, and ozone. This review comprehensively examines fundamental ACP mechanisms, discharge configurations, and their applications within plant-based food safety systems. It critically evaluates recent advancements in inactivating microorganisms, degrading mycotoxins and pesticides, and modulating enzymatic activity, while also exploring emerging applications in bioactive compound extraction, drying enhancement, and seed germination promotion. Crucially, the impact of ACP on the quality attributes of plant-based foods is summarized. Treatment parameters can alter physicochemical properties covering color, texture, flavor, acidity, and water activity as well as nutritional constituents such as antioxidants, proteins, lipids, and carbohydrate content. As an environmentally friendly, low-energy-consumption technology with high reactivity, ACP offers transformative potential for enhancing food safety, preserving quality, and fostering sustainable agricultural systems. Full article

The emergence and dissemination of extended-spectrum beta-lactamase (ESBL)-producing bacteria pose a major public health threat, necessitating a One Health approach to addressing this threat. Thus, the diversity, ESBL production, and potential public health implications of Gram-negative bacteria recovered from man-made lakes and surrounding lettuce in Yamoussoukro, Côte d’Ivoire were assessed in this study. Also, the lakes’ physicochemical parameters were assessed and correlated with bacteria community using Pearson correlation. A total of 68 Gram-negative bacterial isolates were recovered from the samples and identified via 16S rDNA gene sequencing. Phylogenetic analysis suggested multiple genus-/species-level variations within the isolates. Escherichia coli was the most prevalent in lake water (39.5%), while Acinetobacter was the dominant genus in lettuce (30%). E. coli isolates showed high resistance to ampicillin (90.9%), cefepime (72.7%), cefotaxime (68.2%), and aztreonam (63.6%). Moreover, ESBL production was confirmed in E. coli isolates (22.05%), predominantly mediated by the bla_CTX-M gene. Multidrug-resistant phenotypes were widespread, yielding similar multiple antibiotic resistance index (MARI) values in water (0.27–0.63) and lettuce (0.27–0.81). These data indicate high environmental contamination, which unfortunately is not being taken into account by lettuce producers according to an interview. Statistical analyses showed a significant relationship between bacterial diversity and lakes’ physicochemical parameters, including dissolved oxygen, pH, and turbidity. The basic education level of farmers, the prevalence of ESBL-producing E. coli, and the high prevalence of MDR Gram-negative bacteria in both environmental and crop sources in Yamoussoukro underscore the need for both integrated surveillance and management strategies to mitigate potential microbial public health risks within a One Health framework. Full article

Climate change increases microbial contamination risks in food, highlighting the need for real-time biosensors. However, food residues often interfere with detection signals, limiting the direct application. An integrated system of filter-assisted sample preparation (FASP) and an immunoassay-based colorimetric biosensor offers the rapid and simple on-site detection of foodborne pathogens in complex food matrices. The accuracy and stability of biosensor analysis were ensured via filter-assisted preprocessing, which separated food residues from bacteria. The system was applied to various food matrices, including vegetables, meats, and cheese brine, using samples spiked at contamination levels ranging from 10² to 10³ CFU per 25 g, thereby demonstrating broad applicability. Bacterial recovery varied by food matrix, with vegetables showing a 1-log reduction and meats, melon, and cheese brine showing a 2-log reduction relative to the initial inoculum. A detection limit of 10¹ CFU/mL was achieved for Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in the final preprocessed sample solutions. Sample preparation took under 3 min, and detection was completed within 2 h under stationary conditions. This approach enables rapid pathogen detection in various food matrices without the need for special reading devices, contributing to food safety as a real-time, rapid-response food biosensor. Full article

Aflatoxins, toxic secondary metabolites produced by Aspergillus species, are widespread contaminants in food and feed, with aflatoxin B1 (AFB1) recognized as the most potent carcinogen. Climate change increases the risk of contamination by promoting fungal proliferation. While the hepatotoxic and enterotoxic effects of aflatoxins are well established, emerging evidence highlights their immunosuppressive and neurotoxic potential. Notably, AFB1 disrupts gut microbiota, compromises intestinal barrier integrity, and induces neuroinflammation via the microbiota–gut–brain axis. Probiotics have shown promise in mitigating these effects by modulating microbial balance, enhancing barrier function, and reducing neuroinflammatory responses. This review summarizes current findings on the systemic toxicity of aflatoxins—particularly their impact on the gut–brain axis—and evaluates the therapeutic potential of probiotics in counteracting aflatoxin-induced damage. Full article

This study investigates contaminants in metalworking fluids (MWFs) from an industrial band saw, focusing on microparticle classification and microbial quantification linked to fluid degradation. Most particles were under 50 µm, primarily aluminum and iron oxides from tool wear; oxygen- and sulfur-containing particles suggested corrosion. Microbiological analysis showed high contamination, with culturable microorganisms exceeding 1000 CFU/mL. A pathogenic strain associated with biodeterioration was identified, underscoring the need for microbial control. Filtration and ozonation have been used as decontamination methods to improve the purity and biological stability of the process fluid. Filtration enabled selective removal of metallic microparticles. Among six nanofiber filters, the Berry filter achieved the highest efficiency (70.8%) for particles ≥ 7.3 µm, while other filters were faster but less efficient. Ozonation proved highly effective for microbiological decontamination, reducing viable microorganisms by over 95%, improving visual clarity, and lowering pH from 9 to 8 while remaining within operational limits. Unlike filtration, ozonation significantly reduced microbial load. The combination of both methods is proposed as a sustainable strategy for maintaining process fluid quality under industrial conditions. These findings support integrated decontamination approaches to extend fluid life, reduce fresh MWF consumption and waste, and enhance workplace hygiene and safety in machining operations. Full article