Search Results (210)

The growing threat of antimicrobial resistance drives the need for innovative and multifunctional therapeutic systems. In this study, a controlled-release system based on a bioactive film composed of gelatin, bacterial cellulose (BC), sericin, citric acid, PEG 400, and nisin was developed for topical applications in infected wound treatment. BC membranes were produced using Komagataeibacter xylinus and enzymatically treated to optimize dispersion within the polymer matrix. The resulting system exhibited a semi-rigid, homogeneous morphology with appropriate visual characteristics for dermatological use. Microbiological assays demonstrated significant antimicrobial activity against Gram-positive (Staphylococcus aureus) and resistant Gram-negative strains (Escherichia coli and Enterobacter cloacae), attributed to the synergistic action of nisin and citric acid, which enhanced bacterial outer membrane permeability. The antioxidant capacity was confirmed through DPPH radical scavenging assays, indicating a progressive release of bioactive compounds over time. Scanning electron microscopy (SEM) analyses revealed good integration of biopolymers within the matrix. These results suggest that the strategic combination of natural biopolymers and antimicrobial agents produced a functional system with improved mechanical properties, a broadened antimicrobial spectrum, and promising potential as a bioactive wound dressing for the treatment of infected skin lesions. Full article

Lymphoma continues to pose a serious challenge to global health, underscoring the urgent need for new therapeutic strategies. Recently, the gut microbiome has been shown to play a potential role in regulating immune responses and influencing cancer progression. However, its molecular mechanisms of action in lymphoma remain poorly understood. This study investigates the antiproliferative and apoptotic activities of gut microbiota-derived metabolites, specifically nisin (N) and urolithin B (UB), individually and in combination 7:3 (5750 μM), against the human lymphoma cell line HKB-11. Comprehensive evaluations were performed using Alamar Blue viability assays, combination index (CI) analyses, reactive oxygen species (ROS) quantification, flow cytometry for apoptosis detection, and advanced bottom-up proteomics analyses. N and UB exhibited potent antiproliferative activity, with the 7:3 combination demonstrating strong synergistic effects (CI < 1), significantly enhancing apoptosis (p < 0.01) and ROS production (p < 0.0001) compared to the untreated control. Proteomics analyses revealed substantial alterations in proteins crucial to ribosomal biogenesis, mitochondrial function, cell cycle control, and apoptosis regulation, including a marked downregulation of ribosomal proteins (RPS27; Log₂FC = −3.47) and UBE2N (Log₂FC = −0.60). These findings highlight the potential of N and UB combinations as a novel and practical therapeutic approach for lymphoma treatment, warranting further in vivo exploration and clinical validation. Full article

The market for non-concentrated (NFC) orange juice is increasing rapidly due to consumer demand for nutrients and flavor. However, it encounters challenges in microbial safety, particularly from Salmonella enterica and Listeria monocytogenes. This study aimed to exploit a bio-preservative for NFC orange juice. Results showed that the cyclic peptide cyclo-zp80r had good antibacterial activity, with minimum inhibitory concentration values of 2–8 μM against S. enterica and L. monocytogenes. It exhibited bactericidal action against S. enterica and bacteriostatic action against L. monocytogenes at a concentration of 128 μM. This study explored the effect of cyclo-zp80r on the pathogenicity of S. enterica and L. monocytogenes. The mortality rate of Galleria mellonella exposed to these pathogens in NFC orange juice decreased from 100% to 60% after cyclo-zp80r treatment, surpassing the effectiveness of nisin. Cyclo-zp80r exhibited depolarization effects on S. enterica and L. monocytogenes. It increased outer membrane permeability and damaged the membrane structure of S. enterica. Cyclo-zp80r also caused distinct morphological changes, mainly cell collapse in S. enterica and localized bubble-like protrusions in L. monocytogenes. It induced reactive oxygen species production and DNA binding. The species diversity and abundance in NFC orange juice were also reduced by cyclo-zp80r, particularly in the genera Pantoea, Aeromonas, Pseudomonas, and Erwinia. Additionally, cyclo-zp80r exhibited excellent stability at high temperature (121 °C, 5 min) and in fresh orange juice. These results suggest that cyclo-zp80r could be developed as an effective food bio-preservative. Full article

Lymphoma continues to pose a significant global health burden, highlighting the urgent need for novel therapeutic strategies. Recent advances in microbiome research have identified gut-microbiota-derived metabolites, or postbiotics, as promising candidates in cancer therapy. This study investigates the antiproliferative and mechanistic effects of two postbiotics, Nisin (N) and Urolithin B (UB), individually and in combination, against the human lymphoma cell line HKB-11. Moreover, this study evaluated cytotoxic efficacy and underlying molecular pathways using a comprehensive experimental approach, including the Alamar Blue assay, combination index (CI) analysis, flow cytometry, reactive oxygen species (ROS) quantification, and bottom-up proteomics. N and UB displayed notable antiproliferative effects, with IC₅₀ values of 1467 µM and 87.56 µM, respectively. Importantly, their combination at a 4:6 ratio demonstrated strong synergy (CI = 0.09 at IC₉₅), significantly enhancing apoptosis (p ≤ 0.0001) and modulating oxidative stress. Proteomic profiling revealed significant regulation of key proteins related to lipid metabolism, mitochondrial function, cell cycle control, and apoptosis, including upregulation of COX6C (Log₂FC = 2.07) and downregulation of CDK4 (Log₂FC = −1.26). These findings provide mechanistic insights and underscore the translational potential of postbiotics in lymphoma treatment. Further preclinical and clinical investigations are warranted to explore their role in therapeutic regimens. Full article

Listeria monocytogenes poses significant risks in acidic foods like unpasteurized fruit juices due to its capacity to survive under stressful conditions. This study evaluated L. monocytogenes survival in orange juice following acid adaptation and exposure to antimicrobial compounds. Acid adaptation was induced using glucose-supplemented or citric acid-acidified media, followed by the evaluation of pathogen survival in orange juice stored at 4 °C, 15 °C, and 25 °C. While glucose adaptation reduced the medium pH to 4.5 and enabled bacterial growth (up to 7.5 total log CFU/mL), citric acid exposure caused around 1.4 log units of reduction. Contrary to expectations, the survival of acid-adapted cells was lower than that of non-acid-adapted cells, particularly in orange juice stored at 25 °C (around 4.8 vs. 1.4 log units of reduction after 6 days). The behaviour of non-acid-adapted cells was evaluated in response to different antimicrobial compounds (citral, coumaric acid, nisin, sinapic acid, and vanillin). Nisin was the most effective, achieving a reduction of about 3.5 log units with a dose of 2 mL/L. Nisin-treated cells also showed reduced survival during simulated gastrointestinal assays (around 1.5 log units of reduction). These results challenge the assumption that acid adaptation universally enhances survival in acidic matrices and highlight nisin’s dual role in microbial control and pathogenicity mitigation. This work underscores the need for tailored stress adaptation studies and natural antimicrobial applications to improve food safety in minimally processed fruit juices. Full article

The increasing demand for reliable food preservation strategies has driven the development of active biopolymer-based films as alternatives to conventional packaging. This study evaluates Nisin/Na-EDTA-enriched alginate and gelatin films for preserving Dosidicus gigas (jumbo squid) during refrigerated storage. Films were formulated using alginate, gelatin 220/280 Bloom, and glycerol, and characterized in terms of their mechanical, optical, and biodegradation properties. Their effectiveness for the preservation of squid fillets was tested, focusing on weight loss and color stability during refrigerated storage. The incorporation of Nisin/Na-EDTA significantly modified the film’s properties: elongation at break increased from 4.95% (alginate control) to 65.13% (gelatin 280 active), while tensile strength decreased from 8.86 MPa to 0.798 MPa (alginate). Transparency was reduced by up to 2.5 times in active agent-incorporated alginate films. All films degraded within 14 days under soil exposure, with polysaccharide-based films degrading faster. In refrigerated storage, squid fillets coated with gelatin–alginate films containing Nisin showed reduced weight loss (24.05%) compared with uncoated controls (66.36%), particularly in skin-on samples. Color parameters and whiteness index were better preserved with gelatin-based coatings. These results demonstrate the potential of gelatin–alginate films with Nisin/Na-EDTA as biodegradable, active packaging to extend the shelf life of high-protein seafood. Full article

Staphylococcus aureus is one of the aetiological agents of mastitis in dairy cattle. Their biofilms are relevant for human and veterinary medicine. It has been shown that some antibiotics at low concentrations can stimulate the production of biofilms, but there is little information on the effects of low concentrations of nisin, which is considered a therapeutic agent and has been added to food products for years as a biopreservative. In our study, we used Staphylococcus aureus strains (n = 28) isolated from dairy cattle. The MIC of nisin were determined using the broth microdilution method. Based on the minimum inhibitory concentration (MIC) results, the following concentrations were selected for further analyses: nisin at 39, 19, 9 IU/mL; nisin in combination with tetracycline at 39 IU/mL + 0.06 μg/mL, 18 IU/mL + 0.06 μg/mL, and 9 IU/mL + 0.06 μg/mL; and tetracycline alone at 0.06 μg/mL. The biofilm-forming capacity was determined via crystal violet staining in 96-well plates, icaD gene expression was determined using the 2−ΔΔCt method, and microscopic evaluation was carried out using scanning electron microscopy. Results: The MICs were 156 IU/mL (46%) and 312 IU/mL (43%) for most strains. Due to large statistical deviations, there were no statistically significant changes in the biofilm-forming capacity or icaD gene expression despite a visible increasing trend. Despite the absence of statistically significant differences, it was observed that for all concentrations analysed biofilm formation was noticeably greater for both nisin alone and for tetracycline and its mixtures than for untreated cells. Conclusions: In our opinion, the effects of nisin, especially at low concentrations, on biofilm structure show a certain worrying trend that may pose a future threat. Full article

Background/Objectives: Listeria monocytogenes is a major foodborne pathogen responsible for listeriosis, a serious illness with high morbidity and mortality, particularly in vulnerable populations. Its persistence in food processing environments and resistance to conventional preservation methods pose significant food safety challenges. Lactic acid bacteria (LAB) offer a promising natural alternative due to their antimicrobial properties, especially through the production of bacteriocins. This study investigates the competitive interactions between Lactococcus lactis and L. monocytogenes under co-culture conditions, with a focus on changes in their secretomes to better understand how LAB-derived bacteriocins can help mitigate the Listeria burden. Methods: Proteomic approaches, including Tricine-SDS-PAGE, two-dimensional electrophoresis, and shotgun proteomics, were employed to analyze the molecular adaptations of both species in response to bacterial competition. Results: Our results reveal a significant increase in the secretion of enolase by L. monocytogenes when in competition with L. lactis, suggesting its role as a stress-responsive moonlighting protein involved in adhesion, immune evasion, and biofilm formation. Concurrently, L. lactis exhibited a shift in the production of its bacteriocin, nisin, favoring the expression of Nisin Z—a variant with improved solubility and diffusion properties. This differential regulation indicates that bacteriocin production is modulated by bacterial competition, likely as a defensive response to the presence of pathogens. Conclusions: These findings highlight the dynamic interplay between LAB and L. monocytogenes, underscoring the potential of LAB-derived bacteriocins as natural biopreservatives. Understanding the molecular mechanisms underlying microbial competition could enhance food safety strategies, particularly in dairy products, by reducing reliance on chemical preservatives and mitigating the risk of L. monocytogenes contamination. Full article

Background/Objectives: Staphylococci are the most common causes of periprosthetic joint infection (PJI); new antimicrobials are needed to manage these difficult infections. Nisin A is a lantibiotic peptide derived from Lactococcus lactis that has antimicrobial activity against Gram-positive bacteria, including staphylococci, and is an FDA-approved preservative used in the food and dairy industry. Here, the in vitro nisin A susceptibility of PJI-associated staphylococci was assessed. Methods: The minimum inhibitory concentrations (MICs), minimum biofilm inhibitory concentrations (MBICs), and minimum biofilm bactericidal concentrations (MBBCs) of nisin A were measured by broth microdilution against 106 staphylococcus isolates isolated from PJI. MICs were assessed using 5 × 10⁵ CFU/mL plus nisin A. For MBICs, biofilms were grown on pegged lids for 6 h, followed by 20 h of treatment. For MBBCs, pegged lids were transferred to plates containing media only for 20 h. The results were determined as the lowest concentrations with no visual growth. Two-dimensional MICs with nisin A and vancomycin were assessed for 20 isolates. Fractional inhibitory concentrations (FICs) were calculated to determine synergistic, additive, antagonistic, or indifferent interactions. Results: The MIC that inhibited 90% of S. aureus and S. epidermidis was 4 µg/mL, apart from for the MRSA subset (8 µg/mL). The MBIC that inhibited 90% of isolates was 4 µg/mL. The MBBCs ranged from 4 to 256 µg/mL. When tested together, nisin A and vancomycin yielded an FIC between 1.25 and 1.5, indicative of indifference, except for one isolate each of MRSA and MSSA, for which an additive effect (FIC of 1) was observed. Conclusions: Nisin A showed inhibitory activity against staphylococci that cause PJI. Full article

The quality modification of chilled, raw conditioned mutton (RCM) after storage significantly impacts consumer preferences, making shelf-life extension and quality preservation crucial. This study evaluated the effects of sodium diacetate (SDA), sodium dehydroacetate (DHA-S), ε-polylysine hydrochloride (PLH), and nisin on RCM quality and bacterial community at concentrations of 3.0, 0.50, 0.30, and 0.50 g/kg, respectively. Major spoilage bacteria were isolated, and the inhibitory effects of these preservatives were studied, leading to the development of compound preservatives. TVC increased significantly during RCM preparation, with continuous increases in TVC and TVB-N levels throughout storage, reaching spoilage thresholds by day 5. Bacterial diversity decreased markedly, with Brochothrix and Pseudomonas dominating. SDA effectively inhibited TVC proliferation and TVB-N formation, maintaining bacterial diversity and reducing Brochothrix and Pseudomonas abundance while promoting the growth of lactic acid bacteria. Five spoilage bacteria strains were isolated, including Serratia liquefaciens B2107-1, a potent meat spoilage bacterium under refrigeration. PLH and SDA demonstrated significant inhibitory activity against this bacterium, with minimum inhibitory concentrations (MICs) of 0.175 and 0.400 mg/mL, respectively. Combining PLH and SDA at 1MIC + 3MIC exhibited a synergistic antimicrobial effect, maintaining RCM quality with reduced SDA usage. These findings demonstrate the significant potential of these preservatives in chilled, raw meat products. Full article

Background/Objectives: Diabetic foot infections (DFIs) are commonly associated with frequent hospitalizations, limb amputations, and premature death due to the profile of the bacteria infecting foot ulcers. DFIs are generally colonized by a polymicrobial net of bacteria that grows in biofilms, developing an increased antimicrobial resistance to multiple antibiotics. DFI treatment is a hurdle, and the need to develop new therapies that do not promote resistance is urgent. Therefore, the antibacterial efficacy of Nisin Z (antimicrobial peptide), a core–shell polycationic polyurea pharmadendrimer (PURE_G4OEI₄₈) (antimicrobial polymer), and amlodipine (antihypertensive drug) was evaluated against S. aureus and P. aeruginosa isolated from a DFI and previously characterized. Methods: The antibacterial activity was analyzed in vitro by determining the minimal inhibitory concentration (MIC) and in vivo in a Galleria mellonella model by assessing the larvae survival and health index. Results: The results indicate that Nisin Z exhibited antibacterial activity against S. aureus in vivo, allowing larvae full survival, and no antibacterial activity against P. aeruginosa. Nisin Z may have reduced the antibacterial effectiveness of both PURE_G4OEI₄₈ and amlodipine. PURE_G4OEI₄₈ significantly increased the survival of the larvae infected with P. aeruginosa, while amlodipine showed no activity against both bacteria in vivo. Conclusions: These findings suggest that both Nisin Z and PURE_G4OEI₄₈ could potentially be used individually as adjunct treatments for mild DFIs. However, further studies are needed to confirm these findings and assess the potential toxicity and efficacy of PURE_G4OEI₄₈ in more complex models. Full article

Foodborne diseases are one of the most serious problems the food sector has to confront, while questions have been raised concerning the effects of several antimicrobial additives on consumer health. Nisin is a peptide produced primarily by Lactococcus lactis with antimicrobial properties mostly against Gram-positive bacteria. It is generally recognized as safe (GRAS) for use in a wide range of food categories. However, its interaction with components of the food matrix, its susceptibility to proteolytic degradation, or the competitive presence of other components may limit its activity. To enhance its effectiveness against Gram-negative bacteria, its combination with essential oils or other antimicrobial components has been investigated. In addition, its encapsulation in several types of nano-delivery systems has been used to protect nisin from food matrix sequestering while regulating its release. In this review, we present how nisin is utilized, alone or in combination with other antimicrobial agents in a range of emulsion types, as well as the standard techniques for the physicochemical characterization of these systems. Full article

Background/Objectives: Nisin A, an antimicrobial peptide produced by Lactococcus lactis, primarily shows antimicrobial activity against Gram-positive bacteria, with efficacy increased when used in combination with an antimicrobial drug. On the other hand, oral candidiasis, caused by Candida, occurs in immunocompromised patients and requires antifungal therapy. However, antifungal drug-resistant Candida strains are increasing worldwide, leading to serious problems. Methods: To examine the effects of nisin A against Candida species, we investigated the combined effects of nisin A and antifungal drugs on the growth and viability of Candida strains. Results: While nisin A alone had no antifungal effect, together with amphotericin (AMPH), it showed synergistic effects towards C. albicans, as well as the non-albican strains C. glabrata, C tropicalis, and C. parapsilosis in checkerboard assay results. Furthermore, nisin A with miconazole (MCZ) or micafungin (MCFG) demonstrated a synergistic or additive effect on those strains. Cell viability assay results showed that nisin A enhanced the fungicidal activity of AMPH against both C. albicans and C. glabrata. Biofilm reduction assays showed that nisin A with AMPH, MCZ, or MCFG inhibited biofilm activity against C. albicans as compared with each antifungal drug alone. Finally, nisin A with AMPH, MCZ, or MCFG resulted in a reduced minimum inhibitory concentration of those antifungal drugs against clinically isolated C. albicans and C. glabrata.Conclusions: When used in combination with nisin A, the antifungal drug dosage can be lowered, thus helping to prevent adverse side effects and the emergence of drug-resistant oral Candida species. Full article

Background: The consumption of unpasteurized fruit juices poses a food safety risk due to the survival of pathogens such as Salmonella Enteritidis and Escherichia coli O157:H7. Methods: This study evaluated natural antimicrobials (nisin, coumaric acid, citral, sinapic acid, and vanillin) in orange juice as a strategy to ensure the control of these pathogens during the preservation of the non-thermally treated juices. Results: The addition of nisin, coumaric, or citral did not alter the juice’s physicochemical characteristics, ensuring product quality. Nisin (1–2 mL/L), coumaric acid (0.25–0.5 g/L), and citral (0.25–0.5 mL/L) were the most effective in reducing bacterial populations. The antimicrobial activity of the most effective compounds was then tested against both acid-adapted and non-acid-adapted bacteria in refrigerated juice, applying Weibull and linear decay models to assess bacterial inactivation. Non-acid-adapted S. Enteritidis showed a rapid 5 log reduction after 30 h of refrigeration with the highest nisin dose, while the acid-adapted strain exhibited a smaller reduction (2 and 1.5 log units for 1 and 2 mL/L, respectively). Citral was effective but excluded due to solubility and aroma concerns. Non-acid-adapted E. coli O157:H7 showed a 5 log reduction with coumaric acid at 0.5 g/L, whereas acid-adapted strains exhibited a lower reduction (around 1.5 log units). Nisin and coumaric acid also reduced bacterial survival in gastrointestinal tract simulations. However, acid-adapted bacteria were more resistant. Conclusions: These findings highlight the potential of these antimicrobials for food safety applications, though further studies should explore their mechanisms and combinations for enhanced efficacy. Full article

With the rapid implementation of high-pressure processing in many sectors of the food industry, considerations associated with pressure-stressed microorganisms are emerging. Nisin was utilized in this study for controlling the proliferation of Listeria monocytogenes and L. innocua inoculated on cold-smoked trout during a 4-week refrigerated shelf-life trial. Wild-type and pressure-stressed phenotypes of Listeria were compared in this study. The pressure-stressed phenotypes were prepared by treating the surrogate strain and pathogen mixture at 103.4 MPa (15K PSI) for 20 min. L. monocytogenes multiplied extensively during the 4-week refrigerated trial and counts were increased (p < 0.05) from 3.68 ± 0.1 log CFU/g on the first week to 6.03 ± 0.1 log CFU/g. Both phenotypes and the surrogate microorganisms illustrated similar (p ≥ 0.05) multiplication trends. Unlike samples subjected to water treatment, nisin was effective (p < 0.05) in keeping the microbial counts lower compared with the controls, particularly earlier during the shelf-life trial. Our study illustrates that the selected surrogate microorganism has comparable sensitivity to nisin relative to L. monocytogenes and thus could be used interchangeably in future public health microbiology challenge studies with similar scope. Additionally, we observed that pressure-stressed L. monocytogenes has proliferation and sensitivity to nisin comparable to wild-type pathogen. Full article