Search Results (1,871)

This study investigated the microbiological composition and antimicrobial resistance (AMR) profiles of artisanal goat and sheep milk cheeses produced in Poland. Ten raw milk cheeses (five each from goat and sheep milk) were analyzed using a combined approach involving culture-dependent enumeration, 16S rRNA gene sequencing, and antibiotic susceptibility testing. Microbial counts revealed substantial variability among the samples, with lactic acid bacteria (LAB) dominating the microbiota. Taxonomic analysis confirmed the predominance of Lactococcus, Streptococcus, and lactobacilli, although marked intra-group heterogeneity was observed. Multivariate analyses indicated that sample-specific factors had a greater influence on microbiome composition than milk origin. Among 170 isolates, 28.7% were classified as multidrug-resistant (MDR), being most prevalent in Enterobacterales (100%) and Enterococcus spp. (73%), whereas LAB exhibited low resistance levels (16.2%). Resistance was most frequently associated with aminoglycosides and β-lactams. The resistance results were interpreted according to CLSI guidelines. These findings demonstrate that artisanal cheeses harbor complex, dynamic microbial ecosystems that may serve as reservoirs of antimicrobial resistance. The results highlight that environmental and technological factors, rather than milk source alone, are key drivers of both microbiome structure and resistance distribution, underscoring the need for targeted AMR monitoring in traditional dairy products. Full article

For the first time, red LED irradiation was applied at pilot scale in the table olive industry to evaluate its influence on Negrinha de Freixo cultivar natural fermentation. Physicochemical parameters, microbial dynamics, and sensory attributes were evaluated between 60 and 95 days, with two irradiation periods (60–70 and 85–95 days). Three conditions were examined: control-static, pumping-brine recirculation, and LED-brine recirculation + red light exposure. Color or texture was not affected. The lowest pH values were consistently observed in the LED-treated samples. Total phenolic compounds in olives showed a slight decrease from 60 to day 95; however, significant differences were only detected between the pumping treatment and the other two conditions. At the end of the first LED irradiation period, a growth of lactic acid bacteria and aerobic mesophilic bacteria was observed in the order of log 1.0 CFU/mL in the brine, and the yeast count (log 1.4 CFU/g) and LAB (log 1.2 CFU/g) in the olives relative to the control, while the second irradiation period did not show a significant effect. Sensory analysis revealed that LED- irradiated olives exhibited the highest hardness (5.6) values, whereas control samples presented the highest perception of putrid defect. Overall, the results demonstrate that red LED photostimulation may be promising for application in the table olive industry. Full article

Antimicrobial resistance (AMR) is a silently escalating global crisis, presenting a specific challenge for the One Health approach. Landscapes can serve as reservoirs of AMR bacteria and genes, while synurban wildlife may act as vectors of bidirectional exchange. However, these species can also be utilised as sentinels of landscape AMR load. Herbivorous avian bioindicators, such as the Common Wood Pigeon (Columba palumbus), continuously sample the landscape during foraging and drinking, providing a homogenous spatial overview on the state of AMR. This study aimed to investigate the potential of this species for assessing the impact of landscape diversity on bacterial communities and their AMR patterns. Toward this objective, two spatial units of 4 km in diameter located at an upstream and a downstream section of a river, relative to a provincial town, were compared using 16 cloacal samples per site. Heterotrophic plate count techniques resulted in 60 isolates, of which 48 were identified, and 35 were tested for AMR using the VITEK 2 Compact system. The association between bacteriological findings and landscape diversity was analysed using Rényi diversity profiles. The Gram-positive/Gram-negative ratio was the only parameter that proved to be significantly different between the two study sites. The investigation detected six MDR isolates, with two methicillin-resistant phenotypes (Staphylococcus gallinarum, Mammaliicoccus lentus) and two carbapenem-resistant Pseudomonas fluorescens isolates. We established that the small sample size limits drawing definitive conclusions. However, exploring the link between landscape diversity and the cultivable faecal microbiota of herbivorous birds is a promising approach for more extensive research. Full article

Background: The Mediterranean diet (MD) represents a nutritionally balanced eating pattern characterized by high consumption of fruits, vegetables, legumes, nuts, whole grains, olive oil, fish, and extra-virgin olive oil as the principal fat source and limited intake of red meat and refined sugars. Emerging evidence indicates that the MD’s anti-inflammatory and antioxidant properties extend beyond systemic health, potentially reducing the risk and severity of periodontitis. This narrative review aimed to synthesize current evidence on the relationship between adherence to the MD and periodontal health outcomes. Methods: A comprehensive electronic literature search was conducted in PubMed without restrictions on publication date. Fourteen studies, ranging from 2019 to 2025, were included, encompassing human, clinical, experimental, and review designs that examined MD adherence and its effects on periodontal parameters. Eligible studies included cross-sectional, cohort, randomized controlled trials; systematic reviews; and animal models assessing clinical periodontal indices, inflammatory biomarkers, or microbial composition. Extracted data included study design, population characteristics, dietary assessment methods, and primary periodontal findings. Results: Most studies demonstrated that greater adherence to the MD was associated with improved periodontal parameters, including reduced probing pocket depth, clinical attachment loss, and bleeding on probing. Interventional trials showed significant reductions in systemic inflammatory markers such as IL-1β, TNF-α, and CRP, along with decreased counts of periodontopathogenic bacteria. Experimental studies further revealed the protective role of oleic acid and polyphenols in regulating macrophage activity, suppressing osteoclastogenesis, and enhancing IL-10 expression via epigenetic modulation. However, heterogeneity in dietary scoring systems, sample characteristics, and follow-up duration limited direct comparison, and not all associations reached statistical significance. Conclusions: Current evidence supports a beneficial association between MD adherence and periodontal health, mediated through anti-inflammatory, antioxidant, and microbiome-stabilizing mechanisms. Further standardized longitudinal and interventional studies are needed to confirm causality and refine nutritional strategies for periodontal disease prevention and management. Full article

Objective: The objective of this study is to evaluate the ability of silver oxide nanoparticle (Ag₂ONP)-functionalized high-efficiency particulate air (HEPA) filters and colloidal Ag₂ONP suspensions to inhibit biofilm formation by major respiratory pathogens causing infections at operating rooms. Background: Respiratory infections caused by bacterial pathogens such as Streptococcus pneumoniae, Pseudomonas aeruginosa and Staphylococcus species are often associated with the formation of biofilms, which confer increased resistance to antibiotics and host immune responses. Effective strategies to prevent biofilm formation on biological surfaces and in air filtration systems are urgently needed in clinical settings. Methods: The biofilm-forming ability of each bacterial strain was assessed by crystal violet microplate assay, viable count or confocal microscopy after prior incubation of the culture medium with Ag₂ONP-coated HEPA filter material or colloidal Ag₂ONP suspension. Results: Both silver-functionalized filters and silver nanoparticle suspensions significantly inhibited biofilm formation by S. pneumoniae and P. aeruginosa, with near-complete suppression observed. In the case of S. aureus and S. epidermidis, the silver nanoparticle suspension showed partial inhibition of biofilm development. Conclusions: Ag₂ONP-functionalized HEPA filters and colloidal Ag₂ONP suspensions effectively prevent biofilm formation by major respiratory pathogens, for both Gram-negative and Gram-positive bacteria. These materials show promise for integration with air filtration and surface coating systems to reduce microbial load and transmission in healthcare environments such as operating room facilities. Full article

In this study, kefir production was investigated using both commercial kefir cultures and kefir grains, with milk treated at different UV-C doses and flow rates. The flow rate was set to 25 or 50 mL/min, and doses of 43.2 and 21.6 J/mL were applied at each flow rate, respectively. In all samples subjected to UV-C treatment, pH values decreased during storage, while % titratable acidity values increased. The kefir samples produced with UV-C-irradiated milk showed increased hardness and consistency, while cohesion and the index of viscosity decreased. The highest effect was observed in samples produced with kefir grain and at a flow rate of 50 mL/min. Lactic acid bacteria, Streptococcus/Lactococcus, and yeast counts in kefir samples produced from UV-C-treated milk increased. Flow rate affected the increase in microorganism counts. The physicochemical, textural, and microbiological changes during storage were more pronounced in kefir samples produced with kefir grains than with powdered cultures. The organic acid levels of kefir samples produced from milk treated with UV-C decreased compared to those of control samples. Furthermore, organic acid values increased during storage in all samples. As the flow rate increased, the amount of organic acids formed decreased (except for malic and formic acid levels). Full article

Unpasteurized fruit juices are prone to microbiological spoilage by bacteria, yeasts, and molds, creating a need for natural preservatives to extend shelf life without compromising quality. Pomegranate peel extract (PPE) exhibits antimicrobial activity primarily against pathogenic microorganisms; however, its effect on spoilage microorganisms in fruit juices has not been previously studied. This work aimed to compare the microbiological stability of unpasteurized apple juice when adding non-encapsulated PPE or PPE microparticles produced by spray drying with inulin (PPE-IN), inulin combined with sodium alginate (PPE-(IN+SA)), or inulin combined with carrageenan (PPE-(IN+CR)) as encapsulating agents. All microparticle systems showed high encapsulation efficiency (>90%), with PPE-IN reaching 94.08%. For the stability study, PPE microparticles (0.018 to 0.023 g/mL) or PPE (0.009 g/mL) were added to 70 mL of juice and stored at 4 °C for 9 days. MAB, molds, and yeasts were then quantified. At 3, 6, and 9 days, the J+PPE-(IN+CR) treatment showed the lowest MAB, molds, and yeast counts in relation to the non-encapsulated PPE and the other microparticle system. These results indicate that PPE-(IN+CR) microparticles provide superior microbiological stability of apple juice up to day 9, suggesting that the combination of encapsulating agents (IN+CR) could control the release of PPE into the juice. Full article

In this study, Chinese medicinal herbs were evaluated as potential antibiotic substitutes for Chinese soft-shelled turtle (Pelodiscus sinensis). Forty-five herbs were initially screened for antibacterial activity against Salmonella enteritidis, Escherichia coli, and Shigella flexneri. Nine herbs exhibiting broad-spectrum inhibitory effects were selected and subjected to microbial fermentation, after which their antibacterial activities were reassessed and applied as dietary supplements in feeding trials. The results showed that fermentation altered the antibacterial activities of several herbs and enhanced their overall functional performance. Dietary supplementation with fermented Chinese herbal medicine did not adversely affect feed utilization but significantly improved hematological parameters, liver and kidney function indicators, antioxidant capacity, and nonspecific immune responses. Furthermore, turtles fed fermented herbal diets exhibited higher survival rates following bacterial challenge. Intestinal microbiota analysis based on 16S rRNA gene sequencing indicated that fermented herbal supplementation modulated microbial community structure by reducing potential pathogens and increasing beneficial bacterial taxa associated with intestinal health. These findings suggest that microbial fermentation effectively enhances the biological efficacy of Chinese medicinal herbs. Fermented herbal feed additives represent a promising green alternative to antibiotics for soft-shelled turtle aquaculture. The global ban on prophylactic antibiotics drives the need for safe, effective feed alternatives. Microbial fermentation of Chinese herbs (FCM) is proposed to enhance efficacy and detoxification, but its comprehensive effects in aquaculture require deeper investigation. This study evaluated compound unfermented (CM) and fermented (FCM) Chinese herbal supplements on the Chinese soft-shelled turtle (Pelodiscus sinensis). Initial screening showed fermentation generally enhanced the antibacterial activity of the herbs against common enteric pathogens (S. enteritidis, E. coli, S. flexneri). Results indicated that the FCM diet significantly improved physiological status, leading to higher red blood cell counts, better liver/kidney function (reduced ALT/AST, UREA), and stronger immune/antioxidant responses (increased Lysozyme and T-AOC) compared to CM or control diets. Critically, the FCM group achieved the highest survival rates across all single and combined pathogen challenges, demonstrating superior protective efficacy. Furthermore, FCM effectively modulated the gut microbiota, enriching beneficial fermentative bacteria. In conclusion, microbial fermentation significantly amplifies the health-promoting and protective benefits of Chinese herbal supplements in soft-shelled turtles, positioning FCM as a promising green alternative for disease control in aquaculture. Full article

Background/Objectives: Urine samples are the most frequently analyzed specimens in clinical microbiology laboratories. Although urine culture remains the gold standard for diagnosing urinary tract infections, it is time-consuming and resource-intensive. Therefore, reliable screening methods capable of predicting urine culture positivity are needed to optimize laboratory workflow. Automated urine analysis based on flow cytometry enables efficient screening and identification of samples with a low probability of bacterial infection, thereby rationalizing microbiological testing. This study evaluated the usefulness of a multivariable approach to support interpretation of flow cytometry results following the implementation of the Sysmex UF-4000 urine flow cytometer. Methods: Routinely collected urine samples from outpatients and hospitalized patients were analyzed using the UF-4000 flow cytometer, with a positivity threshold of ≥100 leukocytes/µL. Urinary parameters were compared between samples with positive and negative cultures. Multivariable logistic regression was applied to identify independent predictors of a positive urine culture. Urinary sediment parameters, including leukocyte, bacterial, fungal, and squamous epithelial cell counts, were assessed as covariates. Results: Urine samples with positive cultures showed significantly higher leukocyte counts (median 355.0, IQR 146.5–1429.4) and bacterial counts (median 9805.2, IQR 1134.3–45,011.5). Fungal and squamous epithelial cell counts differed only slightly between groups, although the differences were statistically significant (p < 0.001). Leukocyte counts were higher in urine samples from which Gram-negative bacteria were isolated compared with samples containing Gram-positive bacterial isolates (p < 0.001). The multivariable model demonstrated the most favorable overall performance, combining high sensitivity with improved specificity and the highest negative predictive value (AUC = 0.927). Optimal cut-off values were 70 leukocytes/µL and 105 bacteria/µL. Conclusions: Leukocyte and bacterial counts were the strongest predictors of positive urine culture results. A multivariable model including only these two parameters demonstrated high diagnostic accuracy and may serve as a practical screening tool to identify urine samples with a low probability of bacterial infection. The implementation of this approach could support more efficient use of urine cultures and help optimize laboratory workflow. Full article

Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric mucosa, with a global prevalence in humans of approximately 40%. It is likely the cause of 90% of gastric cancer (GC) cases and thus considered the most prominent driver of GC development. However, during gastric mucosal atrophy, other bacteria such as nitrate-reducing bacteria (NRB) also proliferate. In this study, we isolated NRB from patients with gastritis and GC to examine their effects on the epithelial cell cycle and production of various cytokines in monocytic cell lines. Bacterial counts (excluding H. pylori and NRB) increased with the progression of gastric mucosal atrophy and were significantly higher in patients with GC. Gastric epithelial cell lines were stimulated with isolated NRB, and the proportion of cells in each cell cycle was measured. Strains from patients with open-type gastritis progressed more rapidly through cell cycles than those from patients with GC. NRB isolated from gastric cancer had high nitrate-reducing activity. Thus, NRB may contribute to GC progression during H. pylori-induced carcinogenesis. Therefore, evaluating gastric atrophy and microbiota may be important for managing the risk of GC. Full article

Sporulation represents a complex metabolic reprogramming process in bacteria. In this study, we used CRISPR-Cpf1 to knock out spoIIE and rsfA in Bacillus licheniformis. The ΔspoIIE strain completely lost sporulataion capacity, while ΔrsfA showed a 25% reduction. Although viable cell counts decreased by 80.7% and 45.7%, respectively, glucose consumption and 2,3-butanediol synthesis remained unchanged, and acetoin synthesis increased by 19% in ΔspoIIE. Per-cell metabolic rates were significantly enhanced: glucose uptake increased 2.7–3.4-fold, acetoin synthesis 2.3–4.2-fold, 2,3-butanediol synthesis 1.7-fold, and heterologous protein expression 10–15-fold. These findings demonstrate that blocking sporulation liberates metabolic resources and enhances the specific productivity of vegetative cells, providing a strategy for engineering high-performance B. licheniformis cell factories. Full article

Background/Objectives: The increasing prevalence of antimicrobial-resistant bacteria highlights the need for improved methodologies to evaluate antimicrobial activity beyond conventional minimum inhibitory concentration testing. While resazurin-based assays are widely used for minimum inhibitory concentration determination due to their simplicity and sensitivity, minimum bactericidal concentration assessment still relies on labor-intensive colony-forming unit counting. The objective of this study was to develop and validate a resazurin-based microwell assay capable of determining both the minimum inhibitory concentration and the minimum bactericidal concentration without routine plate counting, thereby simplifying bactericidal evaluation. Methods: A two-step resazurin-based fluorescence assay was designed and performed in microplates. After determining the minimum inhibitory concentration using resazurin as a metabolic indicator, well-showing inhibited bacterial growths were subjected to a regrowth phase by transferring aliquots into fresh antimicrobial-free medium containing resazurin. This additional step allowed discrimination between reversible metabolic inhibition and irreversible bacterial death. The method was evaluated using ciprofloxacin and chloramphenicol against four bacterial species: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Minimum bactericidal concentration values obtained using this assay were compared with those obtained through conventional colony counting on agar plates. Results: Minimum bactericidal concentration values obtained using the two-step fluorescence assay were fully concordant with the conventional colony-forming unit counting method for all tested antibiotics and bacterial species. Conclusions: The proposed two-step resazurin-based microwell assay represents a rapid, reliable, and less labor-intensive alternative for the determination of both the minimum inhibitory concentration and the minimum bactericidal concentration, with potential applications in clinical and industrial microbiology laboratories. Full article

Micropropagated plantlets, after removal from controlled laboratory conditions, require an acclimatization period. Adaptation to the new environment induces anatomical and physiological changes controlled by cellular processes. This study investigated the involvement of the primary proton transport systems of total membranes in pineapple root colonization by diazotrophic bacteria and in the development of plantlets treated with different nitrogen doses, allowing an understanding of nutrient absorption and accumulation dynamics. The experiment followed a randomized block design (RBD) in a factorial scheme (2 × 3 × 2), with two inocula (a mixture of diazotrophic bacteria containing Burkholderia sp. UENF 114111, Burkholderia silvatlantica UENF 117111, and Herbaspirillum seropedicae HRC 54, and another without bacteria), three urea doses (0, 5, and 10 g L⁻¹), and two evaluation (90 and 150 days) and bacterial counting times (30 and 150 days), with three blocks. Diazotrophic bacterial populations were lower in older plantlets. H⁺ transport mediated by P H⁺-ATPases changed with acclimatization time. Inoculation did not induce transport; however, the F_max of V H⁺-ATPase was lower without nitrogen fertilization. Nitrogen fertilization affected V H⁺-ATPase proton transport activity in root membranes. The presence of diazotrophic bacteria did not induce proton transport. On the other hand, nitrogen fertilization and acclimatization time affected the proton transport activity mediated by H⁺-ATPases isolated from roots of micropropagated pineapple. Full article

2,6-Dichlorophenolindophenol (DCIP) is a redox dye and colorimetric reagent previously shown to enable rapid quantification of laboratory cultures of oral microorganisms. DCIP is reduced by viable microbial cells, resulting in loss of its blue color that can be measured spectrophotometrically. Previous studies demonstrated that several strains of oral bacteria and yeasts grown in culture reduce DCIP, with significant correlations observed between increasing viable plate counts and DCIP reduction. The present investigation expanded upon these studies by evaluating DCIP as a method for assessing heterogeneous mixtures of oral microorganisms collected from human subjects. Oral rinse samples were obtained from 184 adults aged 18–70 years and analyzed for DCIP reduction and viable bacterial counts. DCIP reduction was observed in all oral samples, and viable bacterial counts spanning an approximately two-log range (~100-fold difference) demonstrated a statistically significant correlation with DCIP reduction (r = 0.74; p < 0.001). Nonviable organisms did not reduce DCIP, and no DCIP reduction occurred in the absence of bacteria. These results support DCIP reduction as a practical, low-cost platform for estimating viable oral microbial burden, with the additional advantage of a visually interpretable colorimetric readout. Full article

Background: The increasing use of electronic cigarettes (ECIGs), especially among youth, has raised concerns about the impact of vaping on oral health. While ECIGs are often marketed as a safer alternative, the existing literature suggests that their use may have detrimental effects on the pulmonary and cardiovascular systems. The oral cavity is the first point of contact for ECIG aerosol, and new reports link vaping to the onset of periodontal disease. It is critical to understand the potential effects of vaping on the oral microbiome, which affects systemic health. This study investigates how flavored E-liquids and commensal bacteria influence the growth of Porphyromonas gingivalis, a periodontal pathobiont, under planktonic and biofilm conditions. Methods: P. gingivalis was grown planktonically in the presence of the supernatants of four streptococcal species (Streptococcus gordonii, Streptococcus intermedius, Streptococcus mitis, and Streptococcus oralis) and flavored E-liquids (tobacco, menthol, cinnamon, strawberry, and blueberry) under anaerobic conditions. Multispecies biofilms, including all the species mentioned above and Fusobacterium nucleatum, were also grown anaerobically and quantified by crystal violet assays, qPCR, and CFU counts. Results: Although E-liquids inhibit P. gingivalis growth under planktonic conditions, the presence of commensal supernatants partially mitigates this effect. However, P. gingivalis growth in multispecies biofilms is increased by E-liquid treatments. Conclusions: This study highlights the enhanced growth of P. gingivalis as part of an oral microbial community in the presence of E-liquids. These results suggest that E-liquid-induced alterations in multispecies biofilms may contribute to the observed dysbiosis in vapers and the associated risk of oral diseases. Full article