Search Results (2,378)

β-blockers are among the most widely prescribed cardiovascular drugs and are increasingly recognised as emerging pollutants due to their persistence, continuous release into aquatic environments, and potential toxicological effects on aquatic organisms. Their removal in conventional wastewater treatment plants is often inefficient, highlighting the need for biological remediation strategies. This study aimed to identify bacterial strains with the highest potential for the biotransformation of β-blockers. Therefore, we isolated and characterised bacterial strains capable of transforming two commonly used β-blockers—propranolol and metoprolol. The strains BB2 and BB3, which were able to transform propranolol and metoprolol, respectively, were identified as Raoultella terrigena and Stenotrophomonas terrae, respectively. BB2 showed broad metabolic versatility, utilising a wide range of carbon sources, whereas BB3 exhibited limited substrate utilisation. Antibiotic resistance profiling further distinguished the strains, with BB2 resistant across multiple antibiotic classes and BB3 largely sensitive. Co-metabolic assays demonstrated that supplementation with specific carbon and nitrogen sources markedly enhanced β-blocker removal, increasing propranolol biotransformation from 5% to 50% and metoprolol from 4% to 36%. These findings demonstrate the bioremediation potential of newly isolated strains and emphasise the importance of aligning microbial metabolic traits with nutrient conditions to improve pharmaceutical removal in wastewater treatment systems. Full article

According to existing ecological problems, one of the promising developments is the creation of polyfunctional materials, which can be biodegradable, along with possessing antibacterial activity. The present research proposes biocomposites based on PLA with silver nanoparticles (AgNPs) and natural polysaccharides obtained in a twin-screw extruder. Introduction of polysaccharides to PLA-based biocomposites with/without AgNPs led to significant decrease in the elastic modulus and tensile strength, while the elongation at break remained almost unchanged. Thanks to the presence of natural polysaccharides, there was intensified biodegradation in soil despite the AgNP availability. The maximal mass loss was 29% for the PLA–PEG₁₀₀₀–starch + AgNPs (80:10:10 + 0.5 wt%) biocomposite. Analyses of the systems before and after soil exposure were carried out using DSC and FTIR spectroscopy methods. According to a thermal analysis, it was found that PLA crystalline regions degrade during exposure to soil. The same feature was detected during the spectral analysis. The intensity of the characteristic absorption bands of PLA decreased. Furthermore, it was found that the dark areas on the surface of the materials are of a polysaccharide nature and may be signs of biofouling of the materials by microbial flora. The tests on fungus resistance showed that biocidal additives such as AgNPs in PLA-based biocomposites with polysaccharides did not inhibit the development of mycelial fungi–biodestructors. And the increased amount of chitosan in the films contributed to their more active destruction by the end of the observation period. It was demonstrated that such biocomposites can inhibit bacterial growth. Full article

The recirculating aquaculture system (RAS) provides a sustainable approach to sustaining aquaculture output while reducing environmental pollution and excessive water consumption. Nonetheless, high concentrations of Total Ammonia Nitrogen (TAN) continue to be a significant obstacle in RAS operations. To address this issue, the Moving Bed Biofilm Reactor (MBBR), with bubble aeration, is important for promoting ammonia degradation. Bubble size impacts the effectiveness of bubble aeration, influencing both oxygen transfer and microbial activity. This research involved a 35-day experiment to evaluate the effects of bubble size, produced by nanobubble and coarse bubble aerators, on biofilm development and TAN decrease. The maximum biofilm thickness of 172.88 µm was recorded during nanobubble aeration, which also produced a higher quantity of microbial colonies (293 × 10⁷ CFU) in comparison to coarse bubble aeration (89 × 10⁷ CFU), as validated by Total Plate Count analysis. SEM–EDX imaging additionally demonstrated a more compact and consistent biofilm structure in the presence of nanobubbles. These results align with an increased TAN degradation efficiency, achieving 83.33% with nanobubble aeration, while coarse bubble aeration reached only 50%. The findings indicate that nanobubble aeration enhances biofilm functionality by improving bacterial dispersion and oxygen availability within the biofilm matrix, thereby promoting a more uniform distribution of microorganisms and nutrients. This mechanism represents a promising approach for improving water quality and overall treatment efficiency in recirculating aquaculture systems (RAS). Full article

Excessive nitrogen addition in farmland on the Loess Plateau reduces soil quality and endangers the atmospheric environment. We designed an experiment to investigate the effects of different nitrogen application rates on the soil physicochemical properties and microbial diversity of spring wheat fields on the Loess Plateau, aiming to identify the optimal nitrogen application rate and avoid the detrimental effects of excessive nitrogen addition. A field experiment was conducted from 2022 to 2023 with four nitrogen (N) application rates (0, 55, 110, and 220 kg·N·ha⁻¹·y⁻¹). This study aimed to assess the changes in soil properties, nutrient contents, enzyme activities, and bacterial community structure. The results showed that increasing N application generally enhanced soil bulk density, nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and microbial biomass nitrogen (MBN) (p < 0.05). In contrast, soil water content initially increased and then decreased. Soil organic carbon and total nitrogen rose markedly with higher N inputs, particularly in the 0–20 cm layer, whereas total phosphorus was less affected. Nitrogen addition stimulated soil enzyme activities (protease, urease, nitrate reductase, and nitrite reductase), though excessive input (220 kg·N·ha⁻¹·y⁻¹) produced inhibitory effects. Actinobacteria (relative abundance: 29–35%) and Proteobacteria (relative abundance: 14–22%) were the dominant phyla in all treatments. Alpha diversity peaked at low nitrogen input (55 kg·N·ha⁻¹·y⁻¹), while high N level reduced evenness and species richness (p < 0.05). Principle Coordinate Analysis (PCoA) revealed that both N application and soil depth shaped microbial community assembly, with deeper layers (20–40 cm) being more sensitive to N input. Correlation analysis indicated that soil moisture, bulk density, and C:N:P stoichiometry were key drivers of bacterial community variation. Overall, moderate nitrogen input (110 kg·N·ha⁻¹·y⁻¹) improved soil fertility and supported microbial functionality, whereas excessive application degraded soil structure and reduced biodiversity. These findings highlight the need for balanced N management strategies in rain-fed agriculture of the Loess Plateau to sustain both productivity and ecological stability. Full article

Nitric oxide (NO), a reactive nitrogen species (RNS), plays a role in multiple biological functions and signal transduction. However, the mechanisms by which NO counteracts stress tolerance in microbes have been poorly explored. In addition, the decomposition of salty food waste poses a significant challenge for food-degrading microbes. Therefore, we investigated how S-nitrosocysteine (CysNO) affects the cellular salt stress response of Burkholderia vietnamiensis TVV75, a strain isolated from a commercial food waste composite. Under the additional 2% NaCl treatment, increased reactive oxygen species (ROS) inhibited bacterial cell growth and viability. In contrast, CysNO treatment alleviated the cellular ROS levels and growth inhibition by augmenting the superoxide dismutase (SOD) and catalase (CAT) activities. CysNO supplementation also promotes the nitrate reduction pathway in B. vietnamiensis TVV75 under salt stress, suggesting NO-mediated nitrogen metabolism for microbial adaptation to salt stress. Furthermore, CysNO restored the intracellular lipid-degrading lipase enzyme activities, which were compromised by salt stress alone. This restoration was accompanied by a concentration-dependent increase in the relative expression of the lipA (lipase A) and ELFPP (esterase lipase family protein) genes. These results suggest that external NO supplementation can regulate redox balance, nitrate reduction, and lipase activity to maintain microbial cell growth in high-salt environments, pinpointing a NO-dependent salt stress adaptation strategy for salt-sensitive microbes involved in food waste decomposition. Full article

Biochar is increasingly recognized as a multifunctional soil amendment that improves soil fertility, nutrient cycling, and crop productivity. Studies across field, greenhouse, and incubation settings show that biochar enhances nutrient retention, reduces leaching, and regulates carbon, nitrogen, and phosphorus cycling. Its effects are shaped by intrinsic physicochemical properties and interactions with soil minerals, microbial communities, and enzymatic processes. Short-term benefits of biochar applications often include improved nutrient adsorption and water regulation, while long-term applications support stable soil organic matter formation, root development, and fertilizer use efficiency. Biochar also reshapes soil microbial diversity and activity. Beneficial bacterial groups such as Proteobacteria and Actinobacteria, along with fungi such as Mortierella, respond positively, enhancing nitrogen fixation, phosphorus solubilization, and organic matter decomposition. Meanwhile, biochar applications could suppress pathogens. Enzyme activities, including urease and phosphatase, are typically stimulated, driving nutrient mobilization. Yet outcomes remain context-dependent, with biochar feedstock, application rate, soil conditions, and crop type influencing results; excessive use may suppress enzymatic activity, reduce nutrient availability, or shift microbial communities unfavorably. Practically, biochar can improve fertilizer efficiency, restore degraded soils, and reduce greenhouse gas emissions, contributing to climate-smart agriculture. Future work should prioritize long-term, multi-site trials and advanced analytical tools to refine sustainable application strategies. Full article

The widespread use of plastics has caused severe environmental pollution, driving interest in biodegradable alternatives like polylactic acid (PLA). However, incomplete degradation of biodegradable plastics under natural conditions may generate micro/nanoplastics that could exacerbate ecological risks. This study investigated the combined effects of UV-aged microplastics from biodegradable PLA and conventional PET, along with sulfamethoxazole (SMX), on the conjugative transfer of antibiotic resistance genes (ARGs) between bacteria. Using UV aging to simulate environmental weathering, the microplastic morphology, adsorption behavior, and interaction with SMX were characterized. The study further evaluated the bacterial viability, ROS level, membrane permeability, and the expression of conjugative transfer-related genes to elucidate the underlying mechanisms. Results showed that aged PLA released significantly more nanoplastics and exhibited higher adsorption affinity for SMX than PET. Combined exposure to aged PLA and SMX significantly enhanced ARG transfer frequency by approximately 14.5-fold compared to the control. Mechanistic studies revealed that this promotion was associated with increased intracellular ROS levels, elevated membrane permeability, and upregulation of conjugative related genes. These findings underscore that biodegradable plastics, after environmental aging, may pose greater ecological risks than conventional plastics, and highlight the importance of considering environmental aging in the risk assessment of plastics. Full article

The long-term success of composite restorations largely depends on the performance of dental adhesives at the adhesive–tooth interface. Despite ongoing improvements, secondary caries remains the leading cause of restoration failure, primarily due to the adhesive layer’s susceptibility to hydrolytic degradation, bacterial invasion, and limited biological functionality. This review provides a comprehensive overview of recent advances in bioactive dental adhesives for preventing recurrent caries, focusing on their mechanisms of action, material performance, therapeutic functions, and clinical potential. Bioactive adhesives combine durable bonding with biofunctional benefits, including remineralization, antimicrobial activity, enzymatic inhibition, and support for tissue regeneration. By integrating these properties, they enhance both the durability of the adhesive interface and oral health. Recent strategies include the incorporation of ion-releasing fillers such as calcium phosphate and bioactive glass, antimicrobial monomers such as MDPB and quaternary ammonium methacrylates, enzymatic inhibitors, and hydrolytically stable resin matrices. Together, these components strengthen the adhesive interface and provide biologically active effects to prevent recurrent caries. Although in vitro findings are promising, challenges remain, including limited long-term clinical data, the absence of standardized evaluation protocols, and barriers to clinical translation. Addressing these gaps is essential to ensure predictable clinical outcomes. Bioactive dental adhesives represent a paradigm shift in restorative dentistry, evolving from passive bonding agents to multifunctional therapeutic materials. By combining structural durability with biological protection, they hold significant potential to prevent recurrent caries and improve the long-term success of composite restorations. Full article

Photocatalytic oxidation of microorganisms is a powerful alternative to established disinfection approaches, applicable to a variety of water matrices. Bacterial vegetative cells, spores, fungi, and viruses, represent potential biopathogens and photocatalysis targets. Inactivation efficiency is usually evaluated by assessing viability through culture. However, additional inactivation assessment approaches are needed, as some microbes, despite being unculturable, remain metabolically active and pathogenic. Nucleic acid quantification approaches (qPCR) can assess nucleic acid release and degradation during photocatalysis. We developed a novel multiplex qPCR assay for simultaneous detection/quantification of genomic DNA from different bacterial and fungal species and of MS2 bacteriophage load. Following small-scale solar titanium dioxide photocatalysis on a microbial suspension mixture containing different biopathogen classes, we assessed photocatalytic efficiency by conventional microbiological assays (culture) and our novel molecular assay. Microbiological assays show a significant reduction in microbe viability within one hour of processing, following previously reported patterns of microbial species resistance. Molecular analysis data show that nucleic acids released in solution due to microbial oxidative damage were significantly reduced due to oxidative degradation within six hours. Through targeting different biopathogen classes, our assay could be a useful tool for assessment of photocatalytic microbe inactivation both in laboratory and real-wastewater applications. Full article

Debaryomyces hansenii has the potential to enhance the flavor profile of traditional fermented meat products. This study investigates the impact of the D. hansenii LY090 strain on the microbial community, lipidome, flavor profiles, and sensory properties of Sichuan bacon. Inoculation with LY090 significantly inhibited the relative abundance of other yeasts, except for Debaryomyces, and altered bacterial community composition. The presence of LY090 led to a notable reduction (p < 0.05) in the levels of ceramide and phosphatidylcholine, resulting in an excessive inhibition of lipid degradation. This further affected the development of flavor and color in Sichuan bacon. However, the concentrations of aldehydes (249.80 μg/kg), ethyl 3-methylbutyrate (81.01 μg/kg), and acetoin (223.91 μg/kg) were all found to be abundant, and the bacon achieved the highest overall acceptance scores when inoculated with both LY090 and commercial starter culture FAST301. Correlation analysis indicated that the differential metabolites exhibited a stronger association with the yeast community, which plays a vital role in the flavor development of Sichuan bacon. These detailed investigations provide meaningful implications for D. hansenii LY090 implementation strategies in the Sichuan bacon industry. Full article

Bacterial exopolysaccharides have emerged as versatile biopolymers for the design of advanced hydrogels with adjustable physico-chemical, mechanical, and biological properties. Among these, levan, a fructose-based exopolysaccharide synthesized by various microbial species, has attracted increasing attention due to its unique structural features, high biocompatibility, and inherent bioactivity. This review provides a comprehensive overview of hydrogel systems derived from bacterial exopolysaccharides, with a particular focus on levan-based hydrogels. We discuss the molecular structure, synthesis pathways, and physico-chemical characteristics of levan that underpin its hydrogel-forming ability. Emphasis is placed on design strategies, including chemical modification, crosslinking approaches, and composite formation, that enable fine-tuning of mechanical strength, swelling behavior, and degradation kinetics. This review further highlights biomedical applications of levan-based hydrogels, encompassing drug delivery, wound healing, rejuvenation, tissue engineering, regenerative medicine, and bioprinting, while addressing current limitations and future research directions. By elucidating the structure–function relationships and emerging fabrication methodologies, this review underscores the biomedical promise of levan as a sustainable and functional biopolymer for next-generation hydrogel technologies. Full article

This study explored the potential of bacterial consortia to remediate real diesel-contaminated agricultural soils. Two consortia were tested: a native consortium isolated from contaminated soil and an exogenous consortium derived from vermicompost. Bacterial communities (consortia and soils) were characterized through high-throughput sequencing. Within 30 days, total petroleum hydrocarbons (TPH) were removed most efficiently by bioaugmentation with the native consortium (53.32%), followed by the exogenous vermicompost consortium (47.14%) and the indigenous microbiota (42.52%). Gas chromatography confirmed the reduction of polycyclic aromatic hydrocarbons (PAHs) with 2–5 rings; however, terphenyl, chrysene, and pyrene persisted. The highest TPH biodegradation rate was observed in the treatment inoculated with the native consortium (208.5 mg/kg per day), followed by the treatment with indigenous microbiota (181.8 mg/kg per day) and the exogenous consortium (161.9 mg/kg per day). Furthermore, hydrocarbon-degrading bacterial populations increased significantly during the first week but declined after day 21, showing a negative correlation with TPH concentrations across all treatments, indicating that the highest bacterial activity and degradation occurred during the first 14 days. Taxonomic analysis identified Actinobacteria as the most abundant phylum in the initial soil, whereas Proteobacteria dominated both the consortia and the bioremediated soils. Significant differences in community structure and composition were observed between the consortia according to their origin, influencing removal efficiency. Dominant genera shifted from Nocardioides and Streptomyces in untreated soil to Pseudomonas, Sphingobium, and Pseudoxanthomonas following biological treatments, while Nocardia, Rhodococcus, and Bacillus remained nearly constant. These findings underscore the effectiveness of adapted bacterial consortia in restoring real diesel-contaminated agricultural soils and highlight potential microbial succession patterns associated with biodegradation and soil ecological recovery. Full article

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine CAS: 1912-24-9) is a widely used herbicide that has been connected to a variety of negative human health and environmental effects. Various bacterial strains utilize a six-step enzyme cascade to fully degrade atrazine. The third step in this pathway, N-isopropylammelide aminohydrolase (AtzC), produces the first non-toxic intermediate, cyanuric acid. As such, AtzC, paired with enzymes catalyzing the first two steps in this pathway, triazine hydrolase (TrzN) and hydroxyatrazine (2-(N-ethylamino)-4-hydroxy-6-(N-isopropylamino)-1,3,5-triazine) N-ethylaminohydrolase (AtzB), can effectively degrade atrazine. All three of these enzymes were successfully encapsulated in tetramethyl orthosilicate (TMOS) gels using the sol–gel method, producing active biomaterials. These materials showed increased protection against proteolytic digestion by the endopeptidase trypsin, as well as increased thermal and pH stability when compared to their non-encapsulated counterparts. AtzB:sol and AtzC:sol also showed increased stability over time compared to soluble enzyme. A combination of all three biomaterials, TrzN:sol, AtzB:sol, and AtzC:sol, was shown to be effective at fully degrading 50 µM atrazine to cyanuric acid in just over an hour and a half, thus establishing a potential bioremediation enzyme cascade for atrazine. Full article

Background/Objectives: Hospital wastewater is a complex effluent containing a wide range of biological and chemical contaminants, including pharmaceuticals, pathogens, and antimicrobial resistance determinants. These discharges pose a growing threat to aquatic ecosystems and public health, particularly in regions where wastewater treatment is insufficient. This study aimed to characterize the chemical and microbiological composition of untreated effluent from a tertiary care hospital in southern Chile, focusing on contaminants of emerging concern. Methods: Wastewater samples were collected at the hospital outlet before any treatment. The presence of two commonly used pharmaceutical compounds, paracetamol and amoxicillin, was quantified using high-performance liquid chromatography (HPLC). Bacterial isolation was performed using selective media, and antibiotic susceptibility testing was conducted via the disk diffusion method following CLSI guidelines. In addition, metagenomic DNA was extracted and sequenced to assess microbial community composition and functional gene content, focusing on the identification of resistance genes and potential pathogens. Results: A total of 42 bacterial isolates were recovered, including genera with known pathogenic potential such as Aeromonas, Klebsiella, and Enterococcus. Antibiotic susceptibility tests revealed a high prevalence of multidrug-resistant strains. Metagenomic analysis identified the dominance of Bacillota and Bacteroidota, together with 56 antimicrobial-resistance gene (ARG) families and 38 virulence-factor families. Functional gene analysis indicated the presence of efflux-pump systems, β-lactamases, and mobile genetic elements, suggesting that untreated hospital effluents serve as potential sources of resistance and virulence determinants entering the environment. Paracetamol was detected in all samples, with an average concentration of 277.4 ± 10.7 µg/L; amoxicillin was not detected, likely due to its instability and rapid degradation in the wastewater matrix. Conclusions: These findings highlight the complex microbiological and chemical burden of untreated hospital wastewater and reinforce the need for continuous monitoring and improved treatment strategies to mitigate environmental dissemination of antibiotic resistance. Full article

Gut microbiota enable wood-feeding insects to digest recalcitrant diets. Two DNA-based analyses were performed. Amplicon sequencing of gut microbiota samples from Cryptocercus punctulatus showed inter-individual heterogeneity with visually distinct ordination patterns; however, no statistically significant differences were detected. Shotgun metagenomics was used to compare the taxonomic and functional profiles of C. punctulatus gut microbiota with those of other xylophagous Dictyoptera. Despite taxonomic differences, C. punctulatus microbiota revealed functional convergence with termites (Mastotermes darwiniensis and Nasutitermes sp.). Carbohydrate metabolism was performed by different bacterial phyla across all insects. All insect species possessed metabolic potential for cellulose, hemicellulose, pectin, and starch digestion, but lignin degradation capabilities were not detected. Termites showed higher abundance of chitin and xylan degradation pathways and nitrogen fixation genes, though nitrogen fixation was also present in Cryptocercus cockroaches. Genes for oxidative stress tolerance were present across all species but were most abundant in cockroaches, particularly, Cryptocercus. All insects harbored antibiotic resistance genes, with highest levels found in cockroaches. These findings indicate that metabolic requirements for wood digestion shape gut microbial community assembly across xylophagous insects, with distinct microbial taxa contributing to cellulose and hemicellulose breakdown. Moreover, the widespread presence of antibiotic resistance genes raises concerns about the potential transmission of antibiotic resistance within insect-associated microbiomes. Full article