Search Results (555)

Antimicrobial resistance (AMR) is a growing global concern, exacerbated by the overuse of antibiotics in livestock farming. Honey bees (Apis mellifera), widely used as bioindicators of environmental contamination, may also serve as sentinels for monitoring the environmental spread of antibiotic resistance genes (ARGs). This study investigated the presence of ARGs and the gut microbiota composition of honey bees sampled from 11 apiaries located in a region of Northwestern Italy characterized by intensive livestock farming. PCR and Sanger sequencing analyses revealed a widespread presence of tetracycline resistance genes—particularly tetB and tetC—as well as occasional detection of blaTEM, qnrB, and int1 genes. tetB and tetC were also identified in three bacterial colonies isolated from bee guts, notably in Hafnia spp. 16S rRNA gene sequencing of the gut microbiota revealed dominance of genera such as Bartonella, Snodgrassella, Gilliamella, Bombilactobacillus, and Lactobacillus. Some samples showed shifts in the microbial diversity. The findings confirm the potential of honey bees as bioindicators for environmental AMR surveillance and underscore the need for further research to elucidate correlations between ARG presence and microbial community structure in honey bees from various ecological contexts. Full article

Freshwater scarcity is a major global issue faced by various regions, and the most common portable water sources globally are estuaries, canals, dams, lakes, and rivers. Existing water resources function as the best sinks for the frequent release of effluents from industrial and residential activities. This common practice often results in water pollution, a deterioration in marine biodiversity, and possible health risks for human populations. This study employed standard analytical methods in assessing the physicochemical and microbial characteristics of water samples collected from the Sundays River estuary in Eastern Cape Province (ECP), South Africa (SA). Microbiological assessment revealed that during the spring season, presumptive Escherichia coli (E. coli) colony counts were 1 cfu/100 mL, while total coliforms (TCs) and fecal coliforms (FCs) were recorded at 42.67 cfu/100 mL and 1 cfu/100 mL, respectively. In the summer season, fecal coliform (FC) counts reached 3.5 cfu/100 mL, while Enterococcus levels were higher, ranging up to 77.75 cfu/100 mL. Furthermore, the average standards of physicochemical parameters assessed in water obtained from both spring and summer seasons ranged as follows: pH (8.71–9.31), temperature (20.98–22.21 °C), turbidity (10–35.55 FNU), total alkalinity (22.25–94.00 mg/L), oxidation–reduction potential (ORP) (8.05–151.6 mV), electrical conductivity (EC) (13,915–40,260 uS/cm), salinity (8.07–25.78 psu), dissolved oxygen (DO) (6.79–7.39 mg/L), total dissolved solids (TDSs) (6960.6–20,125 mg/L), and biochemical oxygen demand (BOD) (0.11–2.94 mg/L). The levels of TDS, EC, turbidity, and salinity in the Sundays River estuary water exceeded the World Health Organization (WHO) guidelines of 2017, rendering the water unfit for even recreational purposes. Additionally, the bacterial levels identified in this study were above the values set by the South Africa Department of Water Affairs (SA-DWAF). The identified microorganisms are perceived as essential indicators of fecal contamination and have the potential to multiply in the environment. Possible pollution may be a result of various municipal effluents consistently discharged into the waterbody. Full article

Watermelon juice is a nutritious yet highly perishable beverage. Conventional thermal pasteurization ensures safety but degrades heat-sensitive nutrients, color, and flavor. Induced electric field (IEF) is an emerging technology that inactivates microorganisms while better preserving quality. However, its effects on the comprehensive quality retention of watermelon juice during storage remain underexplored. This study investigated the efficacy of IEF treatment on the microbial inactivation and quality preservation of watermelon juice during 25 days of storage at 4 °C. Freshly extracted watermelon juice was subjected to low-temperature IEF at 65 °C (IEF1) for 101 s and 60 °C (IEF2) for 88 s, with conventional pasteurization (65 °C, 30 min) as a control. The results showed that no colonies were detected in the IEF2 group throughout the 25-day storage period. Both IEF treatment and pasteurization effectively inhibited juice acidification. Soluble solids content and electrical conductivity remained stable under refrigeration, and the IEF group showed slower and more controllable acidity on day 25. Notably, the IEF1 group retained the highest lycopene content at the end of storage, while the IEF2 group maintained the highest total phenolic content (TPC). Furthermore, IEF treatment effectively mitigated color deterioration and preserved carbohydrate stability during refrigeration. Flavor analysis revealed that the taste profile of the IEF2 group at the initial storage stage closely resembled that of fresh watermelon juice. Over the 25-day period, the relative content of key volatile compounds characteristic of fresh watermelon decreased by only 3.64% in the IEF2 group. Full article

Accurate identification of cariogenic bacteria is crucial for understanding caries development in children. Classical culture methods often underestimate microbial diversity, while polymerase chain reaction (PCR) can detect species that are difficult to cultivate. The aim of this study was to compare culture-based and PCR-based methods for detecting key cariogenic microorganisms in the carious dentin of pediatric patients. Thirty dentin samples were collected from the permanent teeth of children aged 8–14 years. Parallel analyses were performed using standard culture techniques and PCR targeting the gtfB gene of S. mutans and the 16S rRNA gene of Lactobacillus spp. Culture results were quantified as colony-forming units, while PCR results were classified as negative, low-positive, or positive. The results show that culture-based methods identified S. mutans in 16.7% of the samples and Lactobacillus spp. in 3.3%, while PCR identified a signal for S. mutans in 43.3% and Lactobacillus spp. in 100% of the samples. PCR-based methods provide higher sensitivity for detecting key cariogenic bacteria, including S. mutans and Lactobacillus spp. However, PCR detects bacterial DNA and does not indicate bacterial viability or activity. Combining molecular and culture-based approaches allows a more comprehensive assessment of the cariogenic microbiota, supporting accurate microbiological evaluation in pediatric caries research. Full article

Recent evidence implicates the gut microbiota in muscle physiology and function via the gut–muscle axis, which portrays bidirectional communication between microbial colonies, their metabolites and muscle tissue. Age-related muscle decline, including sarcopenia and muscle atrophy, has been associated with shifts in gut microbiota composition and lower levels of microbial metabolites, such as short-chain fatty acids (SCFAs), thereby expanding muscle health research toward microbiota-based therapies. Postbiotics, defined as preparations of inanimate microorganisms and/or their components, are gaining attention as a novel approach to combating muscle decline through modulation of microbiota–host communication, yet a comprehensive review of this topic is currently lacking. Preclinical studies demonstrate that postbiotics may exert anabolic effects while attenuating catabolism, inflammation, and cellular senescence, with associated improvements in grip strength, endurance capacity, and muscle morphology. Although clinical evidence remains limited, available studies indicate that postbiotics may have beneficial effects on muscle strength, endurance, and overall physical performance in humans. By synthesizing recent preclinical and clinical evidence, this review addresses an important gap in the literature, offering a comprehensive and mechanistically informed perspective on the potential role of postbiotics in modulating muscle health, particularly in the context of sarcopenia- and atrophy-associated muscle phenotypes. Full article

(1) Background: University food service establishments are complex environments, where high turnover and handling practices create conditions for microbial persistence. Food-contact surfaces (FCSs) and handlers’ hands (FHs) function as dynamic reservoirs, facilitating the circulation of contaminants within these institutional settings. This study aimed to characterise the microbiological contamination of FCSs and FHs in university food service establishments in Northern Portugal and to evaluate their role as interconnected environmental reservoirs within the indoor built environment. (2) Methods: A total of 590 samples were analysed from two universities in Northern Portugal (L1, L2), comprising 380 FCS and 210 FH samples. Aerobic colony counts (ACCs), Enterobacteriaceae, and Moulds and yeasts (MYs) were analysed according to ISO methods. FH samples were additionally screened for Escherichia coli and Staphylococcus spp. (3) Results: Overall, 35.5% of FCSs were classified as non-compliant, according to microbial criteria based on guideline values from the National Health Institute Dr. Ricardo-Jorge (INSA), with non-compliance primarily driven by elevated ACCs and MYs. Based on a Generalised Linear Model (GLM), establishment types (canteens vs. cafes) were associated with Enterobacteriaceae levels (p = 0.016), whereas ACCs and MYs were not significantly associated with district, establishment type, or functional surface category (p > 0.05). Differences between left and right hands showed small effect sizes, and location was a highly significant determinant of hand hygiene acceptability. (4) Conclusions: FCSs and FHs act as relevant contamination reservoirs in these settings. The results indicate that Enterobacteriaceae levels on FCSs differed between establishment types, while ACCs and MYs showed no significant variation across the evaluated environmental factors. Marked differences in hand hygiene acceptability between campuses support the implementation of targeted interventions, including the optimisation of cleaning and disinfection protocols, the structured training of food handlers, and the routine microbiological monitoring of surfaces and hands to improve institutional food safety. Full article

The western honey bee (Apis mellifera) represents a key pollinator for both crops and wild plants, and its global decline raises serious concerns for ecosystem stability and agricultural productivity. Several biotic and abiotic factors are responsible for colony losses, including alterations in the bee microbiota, which is essential for host metabolism, development, and immune responses. In this study, we employed both molecular protocols and metagenomic approaches based on Next-Generation Sequencing (NGS) to characterize the microbial composition and identify commensal, symbiotic, and pathogenic microorganisms, both known and emerging, associated with A. mellifera colonies from 20 apiaries across the Italian territory. Molecular screening revealed Vairimorpha ceranae, Lotmaria passim, Crithidia mellificae and several viruses, including Sacbrood virus (SBV), Black Queen Cell virus (BQCV), Deformed Wing virus (DWV), Chronic Bee Paralysis virus (CBPV) and Acute Bee Paralysis virus (ABPV). 16S rRNA gene sequencing highlighted a bacterial community mainly composed of the Lactobacillus, Gilliamella, and Snodgrassella genera. Virome analysis detected members belonging to the families Dicistroviridae and Iflaviridae, as well as previously unreported viruses in Italy, such as Apis rhabdovirus (ARV-1, ARV-2), Bee Macula-like virus (BeeMLV), and Lake Sinai virus (LSV). This research expands current knowledge of the A. mellifera metagenome, offering valuable insights for epidemiological surveillance and diagnostic assay development. Full article

Background: The emergence of alternative methods of obtaining groceries since the COVID-19 pandemic has raised new concerns regarding food safety. In this study, we sought to evaluate these concerns by evaluating how the procurement method of ground beef impacts the microbial load in the beef, as this has not been thoroughly studied. Methods: Specifically, we compared beef samples obtained from in-store shopping, grocery delivery, and meal kit delivery services to determine if these new, more convenient methods of grocery shopping impact the total microbial load or Escherichia coli present in the beef. We homogenized a total of 65 beef samples and plated dilutions on trypticase soy agar, MacConkey agar, and CHROMagar. Results: We found that in-store samples had the highest microbial load with an average of 5.06 log CFU/g, while grocery delivery samples resulted in an average of 4.76 log CFU/g and meal kit samples had an average of 4.23 log CFU/g when plated on TSA. This represents a 6.7-fold change between in-store samples and meal kit samples. These differences were not statistically significant (p = 0.1, ANOVA). When plated on MacConkey agar, in-store samples had a bacterial count at 3.0 log CFU/g, while grocery delivery samples had 2.99 log CFU/g and meal kit delivered samples had 3.05 log CFU/g. Suspected E. coli O157 colonies were detected using CHROMagar plates, as these plates function to change the coloration of positive E. coli O157 colonies to pink. Suspected E. coli O157 colonies were observed in three in-store samples, two grocery delivery samples, and one meal kit sample. After confirmatory agglutination testing, one meal kit sample was confirmed as E. coli O157. Conclusions: While trends suggest possible lower microbial contamination in delivery methods versus in-store shopping procurement, no statistical significance between methods was found. These findings indicate no significant changes in microbial loads in delivered ground beef, and the high variance suggests that all procurement methods still pose some level of risk. Full article

Functional amyloids are widely distributed in bacteria and play important roles in biofilm formation and microbial physiology. However, most currently known bacterial amyloids have been identified through sequence homology to a limited number of prototype proteins, such as the curli subunit CsgA of Escherichia coli. This approach may overlook amyloidogenic sequences that lack recognizable similarity to these canonical systems. In this study, a cross-species, motif-based computational strategy was used to explore whether conserved sequence features derived from mammalian serum amyloid A (SAA) proteins could provide clues for identifying potential amyloidogenic motifs in bacterial proteomes. Comparative analysis of mammalian SAA isoforms identified a conserved sequence segment with predicted aggregation propensity, within which the hydrophobic motif SIAIILCILIL was observed in murine SAA3. Database searches revealed that similar sequence motifs occur in several proteins encoded by Gram-positive bacteria, including multiple proteins in Clostridioides difficile. To further explore whether C. difficile produces extracellular structures capable of interacting with amyloid-binding dyes, Congo Red-supplemented agar assays were performed. After 48 h of growth, both clinical isolates and a laboratory reference strain exhibited Congo Red-binding colony phenotypes. Because Congo Red binding can arise from several extracellular components and cannot be attributed to a specific protein or sequence motif, these observations should be interpreted cautiously. Taken together, this study presents a motif-based computational framework for identifying candidate amyloidogenic motifs across species and highlights sequence features in bacterial proteomes that may warrant further biochemical and structural investigation. The results should be regarded as hypothesis-generating and provide a basis for future experimental validation of potential amyloid-forming proteins in bacteria. Full article

We evaluated the indoor environmental quality of the administrative office at University Medical Center Ho Chi Minh City branch 2 and implemented a multi-stage engineering control strategy to optimize occupational health conditions. A cross-sectional assessment monitored important air quality parameters, including carbon dioxide (CO₂), fine particulate matter (PM2.5 and PM10), humidity, and illumination. Following baseline measurements, an integrated system was deployed to address pollutant mass balance, consisting of High-Efficiency Particulate Air (HEPA) filtration units for mechanical particle scrubbing, ceiling-mounted axial fans to induce forced convection, and ultraviolet-C germicidal lamps for photochemical disinfection. Post-intervention results demonstrated significant gains in system removal efficiency. CO₂ concentrations decreased by over 60% due to enhanced volumetric air exchange, while PM2.5 levels decreased by more than 40% through interception and diffusion mechanisms within the HEPA media. Furthermore, UVC irradiation achieved a 90% reduction in viable airborne microbial colonies. The results of this study show that low-cost, scalable environmental engineering controls and fluid dynamic optimizations effectively mitigate indoor air pollution and enhance workplace stability in healthcare administrative settings. Full article

The methodical work describes all the necessary steps for establishing a stable oral ex vivo biofilm using saliva and crevicular plaque samples from periodontal healthy donors. First, cover slips were preconditioned with saliva supernatants and subsequently inoculated with crevicular plaque suspensions. Ex vivo biofilm formation was characterized by confocal laser scanning microscopy (cLSM) after 1, 4, 24, 48 and 72 h of anaerobic cultivation. Exemplarily, the inhibitory characteristics of blackcurrant fruit extracts [all-fruit juice (AFJ); alcoholic fraction from berry skins (AFBS)] were observed on 1, 4 and 24 h-aged ex vivo biofilms. Chlorhexidine (CHX, 0.2%) served as positive control. After direct contact (3 min), biofilms were dispersed, plated onto agar and anaerobically cultivated for 24 h. Early ex vivo biofilms (1 h-biofilm) showed scattered microbial colonies. After 4 h of cultivation, a multilayered biofilm was formed. Biofilm mass gradually increased, displaying a complex polymicrobial structure after 24 h. At 72 h, the biofilms had a dense three-dimensional appearance. Treatment with AFJ and CHX was more efficient in inhibiting biofilm growth compared to AFBS. Early biofilms (1 h, 4 h) were more susceptible to AFJ and CHX compared to 24 h-biofilms. The introduced model can be recommended for testing the efficiency of plaque-controlling agents. Full article

In ruminant nutrition, the lignocellulosic complex is a primary constraint limiting the utilization of dietary fiber. The objective of this study was to evaluate the effects of inoculating lignin-degrading bacteria (LDB) isolated from the ruminant rectum on in vitro rumen fermentation characteristics. Rectal fecal samples were collected from healthy beef cattle, dairy cattle, buffaloes, and goats (n = 4 per species) using the grab sampling technique. Twenty-eight bacterial colonies were isolated through enrichment and screening on media containing sodium lignosulfonate. Lignin degradation efficiency was assessed spectrophotometrically, while laccase activity was determined using a 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) oxidation assay. Seven isolates exhibiting ligninolytic activity (1.4–5.6% degradation efficiency) were selected to evaluate their effects on in vitro rumen fermentation using a completely randomized design with four replicates. LDB treatments were standardized to a concentration of 2.4 × 10⁵ colony-forming units/mL of rumen fluid medium, while the control received an equal volume of a 0.85% sterile NaCl solution. A rice straw-based total mixed ration served as the substrate, with rumen fluid collected from beef cattle. All treatments were incubated for 48 h. Notably, isolate BC3 consistently enhanced in vitro dry matter digestibility (23.1%), total gas production (18.6%), and total volatile fatty acid concentrations (13.2%) relative to the control and other LDB isolates (p < 0.01). All seven LDB isolates were identified as Gram-negative, rod-shaped, facultative anaerobic bacteria that exhibit catalase activity and tolerate moderately acidic conditions. Phylogenetic tree analysis based on 16S rRNA gene sequencing identified isolate BC3 as being closely related to Escherichia coli strains. These findings demonstrate that the ruminant hindgut is a promising source of LDB with the functional potential to enhance feed digestibility and fermentation end-products in the rumen. Future research should prioritize in vivo trials to evaluate the safety and efficacy of LDB as a direct-fed microbial, specifically focusing on its impact on animal performance and health. Full article

Wastewater contamination by toxic heavy metal ions poses a huge threat to ecosystem integrity and human health. Herein, we designed a polyelectrolyte (T-PEI) with a tunable positive charge property to construct a layer-by-layer (LBL) nanofiltration membrane for efficient heavy metal ion removal. The T-PEI was obtained via a Mannich reaction between polyethyleneimine (PEI) and tetrakis (hydroxymethyl) phosphonium chloride (THPC). The introduction of THPC imparted T-PEI with a strong and tunable positive charge, attributed to the quaternary phosphonium groups in THPC. Converting the weakly charged PEI into the strongly charged T-PEI allowed regulation of both T-PEI’s deposition behavior and the electrostatic interactions with sodium polystyrenesulfonate (PSS) during LBL assembly. As a result, after depositing only one bilayer, the positively charged PSS/T-PEI membrane achieved a pore size radius of 0.35 nm, meeting the typical criteria for nanofiltration membranes. Under the optimal preparation conditions, the resultant membranes exhibited a water flux of 38.1 L m⁻² h⁻¹ and high rejections to various heavy metal ions at low operation pressure, such as Cr³⁺ (99.8%), Ni²⁺ (96.1%), Cu²⁺ (92.5%), and Mn²⁺ (90.3%). Additionally, the membrane possessed robust operation stability, along with excellent antifouling/bacterial performance. After cyclic filtration of a lysozyme solution, the flux recovery ratio reached 94.7%. The membrane also exhibited effective bactericidal activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with no visible microbial colonies observed. This work highlights the effectiveness of tailoring polyelectrolyte characteristics in enhancing the LBL membrane performance and presents a promising LBL nanofiltration membrane for heavy metal ion removal. Full article

Objectives: To quantitatively evaluate the inhibitory effects of commercially available probiotic formulations (Probien, Enterogermina, Reflor) applied as intracanal medicaments against mature dual-species biofilms of Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans) using a qPCR-based in vitro root canal model, with calcium hydroxide included as the reference intracanal medicament for comparison. Materials and Methods: Root canal specimens containing mature dual-species biofilms were medicated with probiotic–poloxamer gel formulations (Probien, Enterogermina, or Reflor) or calcium hydroxide (reference inhibitory control); infected but untreated canals served as the non-inhibitory control, and sterile non-inoculated specimens were included to confirm procedural sterility. After a 7-day intracanal application period, microbial loads were quantified at baseline and post-treatment by qPCR, and results were expressed as delta cycle threshold (ΔCt), colony-forming equivalents (CFE/mL), and percentage reduction values. Results: A total of 78 specimens (n = 13 per group) were analyzed. No significant intergroup differences were found in E. faecalis ΔCt or reduction percentages (p > 0.05), indicating its persistence despite intracanal medication. For C. albicans, differences among groups were significant (p < 0.001). Calcium hydroxide showed the strongest antifungal effect, producing marked ΔCt and CFE reductions versus probiotic and positive control groups, whereas probiotic formulations displayed only limited antifungal activity and no measurable inhibition against E. faecalis. Conclusions: Under the conditions of this in vitro model, the tested commercially available probiotic formulations—originally developed for gastrointestinal use—did not demonstrate significant antimicrobial effects against mature E. faecalis–C. albicans biofilms. These findings should be interpreted in the context of the absence of probiotic formulations specifically designed for intracanal use and the distinct ecological characteristics of the root canal system, which represents a closed, low-oxygen environment dominated by hard-tissue surfaces. Rather than excluding the potential of probiotics in endodontics, the present results highlight the need for root canal–adapted probiotic strains and delivery strategies tailored to intracanal conditions. Clinical Relevance: This in vitro study provides experimental insight into the limitations of directly applying commercially available gastrointestinal probiotic formulations within the root canal system. The findings highlight the importance of developing root canal–specific probiotic strains and delivery strategies tailored to the unique ecological conditions of the intracanal environment, thereby informing future translational and experimental research in biological endodontics. Full article

Background: Persistent endodontic infections involving Enterococcus faecalis and Candida albicans are a major cause of root canal treatment failure. Although conventional irrigants, such as sodium hypochlorite and chlorhexidine (CHX), exhibit strong immediate antimicrobial activity, microbes may survive and recover from the initial antimicrobial effect, hence limiting their effectiveness, especially in complex root canal anatomies and in the apical terminus of the tooth. Antibacterial dressing techniques were not proven satisfactory due to depletion of the antibacterial component or difficulty in spreading it evenly along the entire root canal. This study aimed to develop and evaluate the antimicrobial efficacy and release characteristics of a novel sustained-release device (SRD), delivering CHX via gutta-percha points coated with a sustained-release formulation used as a temporary intracanal medicament. Methods: Gutta-percha points were coated with two sustained-release CHX varnishes (CHX1 and CHX2) or a placebo and assessed in vitro. Antimicrobial activity against E. faecalis and C. albicans was evaluated using agar diffusion assays over time. Release kinetics were analyzed using Rhodamine-labeled SRD in a 3D-printed acrylic molar tooth model via fluorescence microscopy. Additionally, biofilm-infected acrylic molar teeth were treated with a placebo, a single 2% CHX irrigation, or SRD-coated gutta-percha points placed as an intracanal dressing prior to obturation. Microbial viability was quantified by colony-forming unit (CFU/mL) analysis from root canals and gutta-percha points. Statistical analysis was performed using one-way ANOVA followed by Tukey’s post hoc multiple comparison test (p < 0.05). Results: SRD-coated gutta-percha points demonstrated sustained antimicrobial activity for up to 21 days against E. faecalis and 19 days against C. albicans. Fluorescence analysis, in an acrylic tooth model, confirmed continuous release for up to 15 days, with pronounced diffusion in the isthmus and palatal canals. In biofilm-infected acrylic teeth models, SRD treatment resulted in a significant reduction of 2–3 log₁₀ CFU/mL compared to placebo groups (p < 0.001) and prevented microbial rebound over the 14-day observation period. In contrast, a single application of 2% CHX solution showed only transient reduction followed by regrowth. Conclusions: Sustained-release CHX delivery via polymer-coated gutta-percha points provided prolonged antimicrobial activity against bacterial and fungal biofilms compared to conventional single-dose CHX application in this in vitro model. These findings support the potential use of coated gutta-percha points as a removable intracanal drug delivery platform prior to final obturation, although further studies incorporating direct-release quantification and in vivo validation are required before clinical translation. Full article