Search Results (2,423)

Recycled bio-wastes such as compost and vermicompost, and bioenergy byproducts such as digestate and biochar are widely acknowledged for their role as soil conditioners capable of preserving soil fertility, maintaining soil health, and acting as a bio-adsorbent of organic soil pollutants (BIOSORs). Moreover, they are attracting increasing attention for use as effective carriers of microbial consortia into arable soils. This study aims to combine selection of bacteria tolerating contaminants of emerging concern (CECs) and their use to fortify BIOSORs. Seventeen bacterial strains isolated from commercial bio-stimulant formulations were studied together with three strains previously isolated and identified as Bacillus subtilis, Bacillus licheniformis, and Serratia plymuthica. All the strains were tested in vitro for their ability to grow under increasing concentrations (0, 0.2, 0.5 and 1 mg L⁻¹) of CECs: bisphenol A, 4-nonylphenol, penconazole, and S-metolachlor. Results highlighted a variability in the tolerance of the bacteria to the tested CECs. The B. subtilis, B. licheniformis, and S. plymuthica were the most promising strains, individually or as consortium, to tolerate individual CECs and their mix. Moreover, they exhibited metabolic activity when inoculated in the BIOSORs. Nevertheless, additional investigations such as quantitative assessment of CECs are needed to validate the methodology. This work contributes to investigate the feasibility of stable and functionally active microbially enriched bio-sorbents (Me-BIOSORs) and provides preliminary evidence supporting the potential to be used in soil–plant systems at the field scale. Full article

Gyms are indoor environments in which many people perform physical exercise and could potentially increase the risks of bacterial contamination and dissemination. Staphylococcus aureus (S. aureus) is one of the most prevalent bacteria in community-acquired infections; thus, the rapid detection and continuous monitoring of S. aureus are crucial for evaluating the hygienic status of gym environments. This work describes the fabrication of a nanochain-based biosensor for S. aureus detection using carboxyl-modified polystyrene (PS) nanoparticles functionalized with a specific antibody. When target bacteria bind to the nanochains, they yield distinct color changes which support the directly visualizable analysis of optical images, recorded using optical microscopy or even a smart mobile phone. In addition to high portability, this biosensor is also capable of the quantification and continuous monitoring of the bacterial load in a gym environment over a broad linear range (10⁰ CFU/mL~10⁵ CFU/mL), with a detection limit of 1 CFU/mL. In summary, this study validated the applicability of the biosensors for the rapid detection and real-time monitoring of gym environmental pathogens. Full article

Mercury (Hg²⁺) contamination in water systems poses a severe environmental and health hazard due to its high toxicity and bioaccumulation potential. In this study, a novel adsorbent was developed by sequentially modifying kaolin via acid–base treatment, titanium dioxide (TiO₂) incorporation, and 3-aminopropyltriethoxysilane (APTES) grafting. Batch adsorption experiments revealed that the fully modified kaolin (TiO₂-loaded and APTES grafted) exhibited the highest adsorption capacity (25.6 mg/g) compared to the acid–base-treated (5.8 mg/g) and TiO₂-loaded (17.7 mg/g) kaolin. Under optimal conditions (75 mg adsorbent dosage; 70 mg/L Hg²⁺; pH 5), the fully modified kaolin maintained its performance even in the presence of varying ionic strengths, natural organic matter, and competing metal ions. Adsorption kinetics followed a pseudo-second-order model, and the equilibrium data were well fitted by the Langmuir isotherm. Antibacterial activity assay revealed that the TiO₂-loaded kaolin effectively inhibited S. aureus (minimum inhibitory concentration = 2.5 mg/mL) and showed moderate activity against E. coli (BL21) (minimum inhibitory concentration = 5 mg/mL). However, antibacterial activity decreased after amine functionalization, indicating a compromise between enhancing adsorption capacity and preserving antibacterial functionality. This study presents a promising cost-efficient approach for the simultaneous removal of Hg²⁺ ions from water matrices and inhibiting bacterial growth, aligning with SDG 6 (Clean Water and Sanitation). Full article

Diesel fuel is among the most persistent petroleum-derived pollutants in soils, posing long-term ecological and toxicological risks, especially in cold-climate regions where natural degradation is limited. Reliable assessment of diesel-contaminated soils remains difficult because conventional solvent-based analyses are incompatible with bioassays, while aqueous extracts underestimate hydrocarbon toxicity. This study evaluated dimethyl sulfoxide (DMSO) as a biocompatible extractant for enzymatic bioluminescent toxicity assays employing the coupled NAD(P)H:FMN-oxidoreductase and bacterial luciferase (BLuc–Red) system. Soil samples artificially contaminated with diesel fuel were analyzed using DMSO extracts in combination with molecular dynamics (MD) simulations to examine enzyme stability in solvent environments. Moderate DMSO concentrations (4 = 6% v/v) maintained enzymatic activity, whereas higher levels caused partial inhibition. Diesel hydrocarbons dissolved in DMSO strongly suppressed luminescence, and soil extracts exhibited a clear dose–response relationship between contamination level and enzymatic inhibition. MD simulations confirmed that neither DMSO nor diesel induced large-scale unfolding of luciferase or reductase, though localized flexibility changes and partial dehydration of active site residues was observed, which may account for the detected inhibition of luminescence at higher DMSO concentrations. These results demonstrate that DMSO provides an effective and biocompatible extraction medium for enzymatic bioluminescent assays, enabling accurate toxicity evaluation of petroleum-contaminated soils and offering a promising tool for ecotoxicological risk assessment in oil-impacted environments. Full article

Extraction of high-quality microbial DNA remains a critical bottleneck in metagenomic research. Environmental samples often produce fragmented DNA and are prone to contaminations that interfere with downstream sequencing, while widely used commercial kits can be prohibitively expensive. Therefore, systematic evaluation of cost-effective alternatives is essential to support large-scale metagenomic studies. In this work, we benchmarked eight commercial DNA extraction kits from Magen, SkyGen, and Sileks against Qiagen reference kits. Four representative sample types were analyzed: freshwater, seafloor sediments, Pacific oyster (Magallana gigas) gut microbiome, and mammalian feces. DNA yield, integrity, purity, PCR inhibitor content, and eukaryotic DNA admixture were assessed. Microbial community composition, alpha diversity, reproducibility, and contamination (“kitome” and “splashome”) were further evaluated using 16S rRNA amplicon sequencing. We revealed that several alternative kits performed comparably or better than the Qiagen reference standard. Magen Soil and Magen Bacterial provided high yields and reproducibility, though the latter produced more fragmented DNA. SkyGen Stool excelled with host-associated samples, while Sileks Soil and Metagenomic kits preserved higher diversity in sediments. Magen Microbiome consistently underperformed. This study identifies multiple cost-effective DNA extraction strategies and provides practical guidance for selecting balanced DNA purification methods for different sample types. Full article

Hyaluronic acid (HA) is a ubiquitous glycosaminoglycan essential for maintaining tissue hydration, structural integrity, and immunological homeostasis in vertebrates. Although traditionally regarded as a host-derived molecule, HA is also produced by a range of microorganisms, most notably Streptococcus spp., through specialized hyaluronan synthases (HAS). Microbial HA and host-derived HA fragments play key roles not only in tissue physiology but also in infection biology, influencing microbial virulence, biofilm formation, and immune evasion. In bacteria, HA-rich capsules promote adhesion, shield pathogens from complement-mediated opsonization and phagocytosis, and facilitate dissemination through host tissues. Conversely, HA-degrading enzymes and reactive oxygen species generate low-molecular-weight HA fragments that amplify inflammation by activating—toll-like receptor 2 (TLR2)/toll-like receptor 4 (TLR4) signaling, contributing to chronic inflammatory states. Furthermore, microbial HA modulates biofilm organization in both bacterial and fungal pathogens, enhancing persistence and antimicrobial tolerance. Clinically, widespread use of HA-based dermal fillers has generated increasing concern over delayed biofilm-associated infections, diagnostic challenges, and complications arising from microbial contamination and host–microbe interactions. Recent advances in HA engineering, including anti-microbial HA conjugates and receptor-targeted biomaterials, offer promising strategies to mitigate infection risk while expanding therapeutic applications. This review synthesizes current knowledge on HA biosynthesis across biological kingdoms, its dualistic role in health and disease, and its emerging relevance at the interface of microbiology, immunology, and biomedical applications. Full article

Natural whey starter (NWS) cultures are microbial consortia characterized by high microbial diversity in terms of genus and species, as well as strains, accounting for the variety of different characteristics and quality of the artisanal fermented food. By means of a combined approach, using plate counts, bacterial isolation, molecular identification, and genotyping, we analyzed 41 colonies isolated from NWS of cow milk used in the production of caciocavallo, a typical pasta filata Italian cheese. Results revealed that 27 of them were lactic acid bacteria (LAB), including Lactococcus lactis as the dominant species, followed by Streptococcus thermophilus, Enterococcus faecium, Limosilactobacillus fermentum, Lactobacillus helveticus, and Lacticaseibacillus rhamnosus. The remaining isolates were taxonomically identified as non-LAB, probably due to environmental contamination. These results were mostly confirmed by metagenomic analysis, with the exception of only three species. Finally, small-scale fermentation experiments were performed in both standard media and skimmed milk to further characterize the newly isolated LAB strains. Overall, our results show that, except for four of the Lactococcus isolates and one Streptococcus, which show multi-drug resistance, the isolated strains under study exhibit levels of acidifying, metabolic properties, and safety parameters, suggesting their potential as starter cultures in cheese production. Full article

Background: Abiotic stresses, such as drought, salinity, temperature fluctuations, waterlogging, and heavy metal contamination, have a detrimental impact on plants, leading to reduced global agricultural productivity. The accumulation of cadmium (Cd) and arsenic (As) in agricultural soil, resulting from both natural and anthropogenic activities, poses significant threats to crop production and food safety. Dehydrins, also known as Group II Late Embryogenesis Abundant (LEA) proteins, are intrinsically disordered proteins that play crucial roles in protecting cellular structures during abiotic stress conditions. These proteins are considered promising candidates for enhancing plant tolerance to environmental stresses through their membrane-stabilizing and protective functions. Methods: This study evaluated the tolerance of Arabidopsis transgenic lines expressing a bacterial dehydrin gene (BG757) to Cd and As stresses using various physiological and biochemical parameters. Results: Compared with the wild-type (WT) control, the transgenic line (35S::BG757-1/Col-0) displayed significant increases in root and shoot growth upon exposure to Cd and As. Furthermore, transgenic plants exposed to heavy metal stress exhibited higher concentrations of chlorophyll, total protein, free proline, total flavonoid, and total phenolic content compared to WT plants. Likewise, transgenic plants showed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and retained higher relative water content under stress conditions. Conclusions: Taken together, these findings suggest that bacterial dehydrins confer enhanced tolerance to heavy metal stress in transgenic Arabidopsis plants, highlighting their potential application in developing stress-resilient crops for contaminated environments. Full article

Background: Environmental surfaces are key reservoirs for pathogen transmission, with the survival of bacteria on fomites influenced by factors such as temperature, humidity, and microbial interactions. This study aimed to determine microbial surface contamination and to determine the antimicrobial resistance profile of bacteria isolated from the indoor surface where the presence of cockroaches was observed in households of the Greater Letaba Municipality (GLM), South Africa. Methods: Swab samples were collected from kitchen countertops and food storage areas with visible cockroach activity. Bacteria were isolated and identified using standard microbiological methods, and antimicrobial susceptibility testing (AST) was conducted with the Vitek^® Automated 2 system. Results: Of the 120 samples collected, 82 (68%) showed bacterial growth, resulting in 190 isolates. The majority of isolates (93%) were Gram-negative, comprising Klebsiella, Pseudomonas, Enterobacter, Escherichia, Serratia, Stenotrophomonas, Pantoea, Raoultella, and Salmonella species, with 98% demonstrating multidrug resistance (MDR) to multiple antibiotics. Resistance was particularly high against gentamicin (94%), fluoroquinolones (88%) and amikacin (77%). Among Gram-positive isolates, all belonged to the Enterococcus species, with 22% being resistant to one or two of the tested antimicrobial agents and 78% exhibiting MDR. Conclusions: The study revealed a high prevalence of antibiotic resistance in both Gram-positive and Gram-negative bacteria isolated from household surfaces. The spread of antibiotic-resistant pathogens via environmental surfaces presents a significant risk to human health, safety, and well-being. Full article

(1) Background: Salmonella are zoonotic pathogens, and rising antimicrobial resistance (AMR) amplifies their public health impact. Asymptomatic horses can act as reservoirs, contributing to environmental contamination and interspecies transmission. This study aimed to estimate the prevalence of Salmonella and characterize AMR patterns in healthy horses from eastern Spain. (2) Methods: Faecal samples from 95 asymptomatic horses were collected once daily over five consecutive days (475 samples in total) and processed under for Salmonella detection. Epidemiological information was obtained through owner questionnaires, and associations with Salmonella shedding were analyzed using generalized linear models. Antimicrobial susceptibility was assessed by minimum inhibitory concentration assays following the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. (3) Results:Salmonella was detected in 25.3% of horses (24/95), with S. Enteritidis, S. Johannesburg, and S. Virchow as the most frequent serotypes. A significant association was observed between proximity of manure storage and bacterial detection (p < 0.001). Among 24 isolates of Salmonella, 88.9% were resistant to at least one antimicrobial, and 50% exhibited multidrug resistance. The highest resistance rates were against sulfamethoxazole and gentamicin, followed by ciprofloxacin and tigecycline. (4) Conclusions: Healthy horses can act as silent carriers of multidrug-resistant Salmonella, highlighting the need for surveillance, strengthened biosecurity, and prudent antimicrobial use within a One Health framework. Full article

Because of their technical qualities, such as resistance to fading and to high temperatures, mineral pigments are still widely used. Among mineral pigments, iron oxide pigments represent a widely used class, because of their diversity of shades (from yellow to red to brown to black) and low toxicity compared to heavy metals-based pigments. However, low toxicity does not mean the absence of adverse effects. We thus investigated the biological effects of two different subtypes of Pigment Red 101, i.e., hematite, produced by two different processes, namely a wet precipitation process and a calcination process. Macrophages were chosen as a target cell type because they represent the main scavenger cell type that is in charge of handling particulate materials in the body. During this comparison, we realized that the calcined pigment was contaminated from the start by bacterial endotoxins, which induced intense inflammatory responses and biased the comparison. After depyrogenation, the calcined pigment proved to dissolve to a higher extent in macrophages, but to show less intense adverse effects (e.g., alteration of the mitochondrial transmembrane potential, oxidative stress and inflammatory responses) than the precipitated pigment in a recovery exposure mode, allowing us to investigate delayed effects of the pigments. Thus, despite their identical pigment number, pigments differing in their structure and in their synthesis induce different responses from living cells, even if administrated in equivalent amounts. This should be taken into account for some applications, such as tattooing. Moreover, endotoxin contamination should also be checked to increase workers’ and users’ safety. Full article

Groundwater represents an essential resource for domestic and agricultural use, and its physicochemical and microbiological quality directly affects public health. This study assessed the bacteriological quality of untreated well water in the province of Fez-Meknes, specifically in the Aïn Tawjdate area, and evaluated seasonal variations in bacterial contamination. During the spring and summer of 2023, groundwater samples were collected from several wells. A total of 139 bacterial strains were isolated and identified using API biochemical galleries. The most frequently detected species were Aeromonas hydrophila gr.1 (6.47%), Aeromonas hydrophila gr.2 (9.35%), Enterobacter cloacae (7.19%), Pseudomonas aeruginosa (10.07%), and Flavimonas oryzihabitans (6.47%), among others. Genetic variability among ten E. cloacae isolates was further explored using ERIC-PCR profiling; the strains differed by more than three fragments and showed less than 80% similarity; therefore, they were considered as distinct ERIC types. Statistical analyses (Chi-square, Fisher’s exact, Tukey HSD, one-way ANOVA, and two-sided Dunnett tests) revealed no significant differences in bacterial load between wells within the same season, with p-values > 0.05 according to ANOVA. However, a significant increase in contamination levels was observed in summer compared with spring. These findings highlight the potential health risks associated with the consumption of untreated groundwater and underline the need for regular microbiological monitoring and improved water treatment practices in rural communities. Full article

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) pose significant health risks through various exposure pathways, including ingestion of contaminated food and water, as well as dermal absorption. Aquatic organisms are especially at risk, as water bodies serve as primary pathways for the transport and transformation of these chemicals. While the biodegradation study was previously performed using a bacterial consortium from the activated sludge compartment at Zeekoegat WWTP, the ecotoxicological implications of the treated effluents remained unclear, particularly given the potential presence of degradation products. To address this gap, the present study used bioassays to evaluate the acute toxicity and endocrine-disrupting potential of PFOS and PFOA. For this purpose, PFOS and PFOA concentrations ranged from 58 ng/L to 1050 ng/L, and two types of bioassays were used: the Daphnia magna acute toxicity test, which examined the short-term lethal effects of the samples on a small freshwater organism (Daphnia magna), and the Yeast Estrogen Screen (YES), which measured estrogenic activity, an important indicator of potential endocrine disruption. Results revealed detectable estrogenic activity at environmentally relevant concentrations, with PFOS showing higher activity than PFOA. The estradiol equivalency (EEQ) values in samples containing PFOA ranged from 0.23 ± 0.029 ng/L to 3.15 ± 0.056 ng/L and from 0.43 ± 0.036 ng/L to 1.96 ± 0.086 ng/L in samples containing PFOS. Daphnia magna bioassays showed 100% mortality in samples containing PFOS at concentrations ≥ 62 ng/L and in samples containing PFOA at concentrations ≥ 142 ng/L, classifying them as ‘Very High Acute Hazard’ falling into Hazard Class V (100% mortality) according to the classification system proposed in 2003 by Persoone and co-workers. These bioassays helped to determine whether the degradation products were more toxic compared to the parent compounds, thereby supporting the objective of this study to assess environmental safety post-treatment. Full article

Air quality in zoo premises is insufficiently investigated, yet scientific interest is growing. In these places, air pollutants such as microorganisms may represent health risk for both animals and exposed people. Thus, maintaining good air quality is crucial for ensuring long-term sustainability of zoo operations. The present study aimed to assess bacterial air contamination level and microclimate conditions in Zagreb Zoo. Measurements were performed in the area for visitors and employees inside four premises, i.e., Monkey House, Tropical House, Rainy Africa, and Bird House, as well as outside the premises in the summer–autumn period. Total number of bacteria in the premises ranged from 4.50 × 10² to 3.70 × 10⁴ CFU/m³, and number of Gram-negative bacteria ranged from 0 to 5.50 × 10² CFU/m³. Total number of bacteria in outdoor air ranged from 50 to 8.50 × 10² CFU/m³, and number of Gram-negative bacteria ranged from 0 to 50 CFU/m³. Total number of bacteria was significantly higher in the Rainy Africa and Bird House as compared to the Monkey House and Tropical House, yielding a significant positive correlation with the number of Gram-negative bacteria in the premises. Total number of bacteria in outdoor air was significantly lower as compared to all investigated premises, except for the Monkey House, yielding a significant positive correlation with the number of Gram-negative bacteria outdoors. Air temperature showed a significant negative correlation with both total number of bacteria and number of Gram-negative bacteria, and airflow rate showed a significant negative correlation with total number of bacteria in the premises. Air temperature showed a significant positive correlation and relative humidity significant negative correlation with total number of bacteria outdoors. Study results can serve in the development of air quality standards in zoos, contributing to finding effective strategies to mitigate health risk from bioaerosols, with implications for occupational and public health, and overall zoo sustainability. Full article

Feed contaminated with the mycotoxin deoxynivalenol (DON) can negatively impact livestock health and performance. Bacteria capable of degrading DON present a method of mitigating its harmful effects. This study aimed to identify microbial consortia from soil samples that could degrade DON. Soil from central (Lacombe, LA) and southern (Lethbridge, LE) Alberta were used as microbial inoculant. The soils were mixed with DON-contaminated wheat (18 ppm/kg) on day 0, and each soil type was divided into triplicate pots (180 g) and placed in a controlled environment for 32 d. Control pots of each soil type were included, which contained no DON-contaminated wheat. On days 0, 7, 14, and 32, 1 g subsamples were collected from pots, serially diluted in a limited medium containing DON (10 µg/mL) as the only carbon source, and incubated for 2 weeks (30 °C). DNA was extracted from the pots across time, as well as the subsample consortia grown in DON-amended medium, and was analyzed for bacterial changes after 16S rRNA gene sequencing. The relative abundance of bacterial genera in soil samples after enrichment with DON-contaminated wheat increased across time compared to the baseline day 0 time point. DON-degrading activity (26%) was only detected in LA soil suspension on day 7, and was highest after 14 days of incubation. The most abundant bacteria in the LA DON-degrading consortia belonged to the Pseudomonas (8.8%), Delftia (7.4%), Acinetobacter (6.4%), Comamonas (5.7%), Stenotrophomonas (5.5%), Shinella (5.5%), Ensifer (5.1%), Agrobacterium (5.0%), Achromobacter (4.7%), and Rhizobium (3.7%) genera. Pseudomonas aeruginosa (n = 9) and Serratia liquefaciens (n = 3) strains isolated from the LA consortia did not degrade DON. Overall, this study shows that the soil contained bacteria capable of degrading DON; however, variation existed depending on the soil’s source. Full article