Adsorption Of Nisin Research Articles

Nymphaea alba leaf powder effectiveness in removing nisin from fermentation broth using docking and experimental analysis

The accumulation of nisin in the fermentation medium can reduce the process's productivity. This research studied the potential of Nymphaea alba leaf powder (NALP) as a hydrophobic biosorbent for efficient in-situ nisin adsorption from the fermentation medium by docking and experimental analysis. Molecular docking analysis showed that di-galloyl ellagic acid, a phytochemical compound found in N. alba, had the highest affinity towards nisin. Enhancements in nisin adsorption were seen following pre-treatment of NAPL with HCl and MgCl2. A logistic growth model was employed to evaluate the growth dynamics of the biosorption capacity, offering valuable insights for process scalability. Furthermore, optimization through Response Surface Methodology elucidated optimal nisin desorption conditions by Liebig's law of the minimum, which posits that the scarcest resource governs production efficiency. Fourier Transform Infrared (FTIR) spectroscopy pinpointed vital functional groups involved in biosorption. Scanning electron microscopy revealed the changing physical characteristics of the biosorbent after exposure to nisin. The findings designate NALP as a feasible adsorbent for nisin removal from the fermentation broth, thus facilitating its application in the purification of other biotechnological products based on growth and production optimization principles.

Highly active nisin coated polycaprolactone electrospun fibers against both Staphylococcus aureus and Pseudomonas aeruginosa

In this study, a wound dressing of electrospun polycaprolactone (PCL) fibers incorporating the antimicrobial peptide (AMP) nisin was fabricated. Nisin was physically adsorbed to the PCL fibers and tested for antibacterial activity against both Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The PCL fibers had an average diameter of 1.16 μm ± 0.42 μm and no significant change in diameter occurred after nisin adsorption. X-ray photoelectron spectroscopy (XPS) analysis of the fibers detected nitrogen indicative of adsorbed nisin and the signal was used to quantify the levels of coverage on the fiber surfaces. In vitro nisin release studies showed a burst release profile with 80 % of the nisin being released from the fibers within 30 min. Air plasma pre-treatment of the PCL fibers to render them hydrophilic improved nisin loading and release. Antibacterial testing was performed using minimum inhibitory concentration (MIC) and surface attachment assays. The released nisin remained active against both Gram positive S. aureus and Gram negative P. aeruginosa, which has previously been difficult to achieve with single polymer fiber systems. Mammalian cell culture of the nisin coated fibers with L-929 mouse fibroblasts and human epidermal keratinocytes (HEKa) showed that the nisin did not have a significant effect on the biocompatibility of the PCL fibers. The results presented here demonstrate that the physical adsorption, which is a post-treatment, overcomes the potential limitations of harsh chemicals and fabrication conditions of electrospinning from organic solvents and provides a drug loading system having effective antibacterial properties in wound dressings.

Enhanced viability and improved in situ antibacterial activity of the probiotic LAB microencapsulated layer-by-layer in alginate beads coated with nisin

In the present study, a layer-by-layer technique was used to prepare alginate-nisin (Alg-N) as coating layer to encapsulate a potential probiotic-protective lactic acid bacteria (LAB) isolate in order to improve its both survival and antibacterial activities in situ. The isolate was identified as Pediococcus acidilactici according to the sequencing results of the PCR products. The mean size of Alg and Alg-N microcapsules was also equal to 762.63 and 501.77 μm, respectively based on the results of field emission scanning electron microscopy. In accordance with the zeta potential data, the Alg-N surrounding layer was confirmed. Furthermore, the Fourier transform infrared findings revealed the adsorption of nisin on the Alg beads. The antibacterial activity of the produced microcapsule on Staphylococcus aureus (100% inhibition) was significantly (P < 0.05) higher than that of the other foodborne bacteria studied. In addition, enhanced viability of the microencapsulated LAB in simulated gastrointestinal conditions and flavored milk, as well as its improved in situ inhibitory effect on S. aureus were verified.

Functionalization of a chemically treated Ti6Al4V-ELI alloy with nisin for antibacterial purposes

This research aims to define a protocol for nisin adsorption onto Ti6Al4V- Extra Low Interstitial content (ELI) alloy to reduce the risk of peri-implant infections. The substrate is, first, etched to get a nanotextured surface with a high density of acidic hydroxyl groups and then functionalized with the antimicrobial peptide nisin. Nisin adsorption is performed at different pH values, in the range of 5–7. The nisin release in inorganic solutions mimicking physiological or pro-inflammatory conditions is tested. The surfaces are characterized by profilometry, SEM/EDS, contact angle and surface free energy measurements, zeta potential titrations, DLS, XPS, and UV–visible spectroscopy. Effective surface adsorption was achieved and maximized at pH 6. The coated surface has high surface energy suitable for tissue integration and it releases nisin in a time longer than 1 day. As a confirmation of the antibacterial properties due to the nisin adsorption, specimens were incubated with Staphylococcus aureus, whose metabolic activity was reduced by ≈ 70% in comparison to the untreated control, and the number of viable adhered colonies was ≈ 6 times reduced. In conclusion, coupling of nisin to a chemically treated titanium surface is promising for a bioactive and antibacterial surface for tissue integration.

Efficient Production of Nisin A from Low-Value Dairy Side Streams Using a Nonengineered Dairy Lactococcus lactis Strain with Low Lactate Dehydrogenase Activity.

Nisin is commonly used as a biopreservative in foods. For industrial production, nisin-producing Lactococcus lactis strains are usually grown to high cell densities to achieve the highest possible nisin titer. However, accumulation of lactic acid eventually halts production, even in pH-controlled fermentations. Here, we describe a nisin-producing L. lactis strain Ge001, which was obtained after transferring the nisin gene cluster from L. lactis ATCC 11454, by conjugation, into the natural mutant L. lactis RD1M5, with low lactate dehydrogenase activity. The ability of Ge001 to produce nisin was tested using dairy waste as the fermentation substrate. To accommodate redox cofactor regeneration, respiration conditions were used, and to alleviate oxidative stress and to reduce adsorption of nisin onto the producing cells, we found it to be beneficial to add 1 mM Mn2+ and 100 mM Ca2+, respectively. A high titer of 12 084 IU/mL nisin could be reached, which is comparable to the highest titers reported using expensive, rich media. Summing up, we here present a 100% natural, robust, and sustainable approach for producing food-grade nisin and acetoin from readily available dairy waste.

Effective adsorption of nisin on the surface of polystyrene using hydrophobin HGFI

Herein, a new method was demonstrated for effective immobilization of the antibacterial peptide nisin on Grifola frondosa hydrophobin (HGFI), without the need of any additional complex reaction. Hydrophobin can self-assemble as a monolayer to form continuous negative-charged surfaces with enhanced wettability and biocompatibility. Adding nisin solution to such hydrophobin surface created antibacterial surfaces. The quantification analysis revealed that more nisin could be adsorbed on the HGFI-coated than to control polystyrene surfaces at different pH values. This suggested that electronic attraction and wettability may play important roles in this process. The transmission electron microscopy, atomic force microscopy and fourier transform infrared (FTIR) analysis indicated the adsorption mode of nisin on the HGFI film, i.e., hydrophobins served as an adhesive layer for binding charged peptides to interfaces. The antibacterial activity of the treated surface was investigated via counting, a nucleic acid release test, scanning electron microscopy, and biofilm detection. These results indicated the excellent antibacterial activity of nisin adsorbed on the HGFI-coated surfaces. The activity retention of adsorbed nisin was demonstrated by immersing the modified substrates in a flowed liquid condition.

Mesoporous matrices for the delivery of the broad spectrum bacteriocin, nisin A

Mesoporous matrices of different pore size and chemical composition were explored as potential delivery matrices for the broad spectrum bacteriocin, nisin A. The adsorption of nisin A onto two mesoporous silicates (MPS - SBA-15, MCM-41) and two periodic mesoporous organosilanes (PMO - MSE, PMO-PA) was examined. It was found that hydrophobic interactions dominated in the adsorption of this peptide to the matrices, lending the highest adsorption to MCM-41 with a small pore size of 2.8 nm. The hydrophobic ethylene-bridged MSE (6 nm pore) improved the loading and protection of nisin A from degradation by a non-specific protease pepsin, over un-functionalised SBA-15 which had a slightly larger pore size and less hydrophobic moieties. Nisin A did not adsorb onto an amine-functionalised PMO. Upon suspension in modified fasted state simulated gastric fluid (pH 1.6), the highest release of nisin A was observed from MCM-41, with a lower release from SBA-15 and MSE, with release following Higuchi release kinetics. No release was detected into modified fasted state simulated intestinal fluid (pH 6.5) but despite this, the suspended matrices loaded with nisin A remained active against Staphylococcus aureus.

The increase of O-acetylation and N-deacetylation in cell wall promotes acid resistance and nisin production through improving cell wall integrity in Lactococcus lactis.

Cell wall is closely related to bacterial robustness and adsorption capacity, playing crucial roles in nisin production in Lactococcus lactis. Peptidoglycan (PG), the essential component of cell wall, is usually modified with MurNAc O-acetylation and GlcNAc N-deacetylation, catalyzed by YvhB and XynD, respectively. In this study, increasing the two modifications in L. lactis F44 improved autolysis resistance by decreasing the susceptibility to PG hydrolases. Furthermore, both modifications were positively associated with overall cross-linkage, contributing to cell wall integrity. The robust cell wall rendered the yvhB/xynD-overexpression strains more acid resistant, leading to the increase of nisin production in fed-batch fermentations by 63.7 and 62.9%, respectively. Importantly, the structural alterations also reduced nisin adsorption capacity, resulting in reduction of nisin loss. More strikingly, the co-overexpression strain displayed the highest nisin production (76.3% higher than F44). Our work provides a novel approach for achieving nisin overproduction via extensive cell wall remodeling.

Stability and Antimicrobial Activity of Nisin-Loaded Mesoporous Silica Nanoparticles: A Game-Changer in the War against Maleficent Microbes.

Antimicrobial agents, such as nisin, are used extensively in the food industry. Here, we investigated various approaches to load nisin onto mesoporous silica nanoparticles (MSNs, 92 ± 10 nm in diameter), to enhance its stability and sustained release. The morphology, size, and surface charge of the as-prepared nanoparticles were analyzed using scanning transmission electron microscopy, dynamic light scattering, and ζ potential measurement. Nisin was either physically adsorbed or covalently attached to the variously functionalized MSNs, with high loading capacities (>600 mg of nisin g-1 of nanoparticles). The results of antibacterial activity analysis of nisin against Staphylococcus aureus showed that, despite the very low antibacterial activity of nisin covalently conjugated onto MSNs, the physical adsorption of nisin onto the unfunctionalized nanoparticles enhances its antimicrobial activities under various conditions, with no significant cytotoxicity effects on mouse fibroblast L929 cells. In conclusion, MSNs can be recommended as suitable carriers for nisin under various conditions.

Promoting acid resistance and nisin yield of Lactococcus lactis F44 by genetically increasing D-Asp amidation level inside cell wall.

Nisin fermentation by Lactococcus lactis requires a low pH to maintain a relatively higher nisin activity. However, the acidic environment will result in cell arrest, and eventually decrease the relative nisin production. Hence, constructing an acid-resistant L. lactis is crucial for nisin harvest in acidic nisin fermentation. In this paper, the first discovery of the relationship between D-Asp amidation-associated gene (asnH) and acid resistance was reported. Overexpression of asnH in L. lactis F44 (F44A) resulted in a sevenfold increase in survival capacity during acid shift (pH3) and enhanced nisin desorption capacity compared to F44 (wild type), which subsequently contributed to higher nisin production, reaching 5346IU/mL, 57.0% more than that of F44 in the fed-batch fermentation. Furthermore, the engineered F44A showed a moderate increase in D-Asp amidation level (from 82 to 92%) compared to F44. The concomitant decrease of the negative charge inside the cell wall was detected by a newly developed method based on the nisin adsorption amount onto cell surface. Meanwhile, peptidoglycan cross-linkage increased from 36.8% (F44) to 41.9% (F44A), and intracellular pH can be better maintained by blocking extracellular H+ due to the maintenance of peptidoglycan integrity, which probably resulted from the action of inhibiting hydrolases activity. The inference was further supported by the acmC-overexpression strain F44C, which was characterized by uncontrolled peptidoglycan hydrolase activity. Our results provided a novel strategy for enhancing nisin yield through cell wall remodeling, which contributed to both continuous nisin synthesis and less nisin adsorption in acidic fermentation (dual enhancement).

Adsorption of nisin into layered double hydroxide nanohybrids and in-vitro controlled release

Layered double hydroxide (LDH) nanohybrid intercalated biomolecules, including oligonecluotides, genes and peptides/proteins, have attracted particular attention since they exhibit improved safety and effectiveness as successful delivery biosystems. The current study specifically investigated the adsorption of nisin peptide and precisely the control of the release of the payload. Adsorption occurred from peptide solution in contact with zinc-aluminum LDH at room temperature, looking out over the influence of the Zn2+/Al3+ ratio, the anion exchange capacity, the nature of the intercalated anion, the host matrix, and the host morphology. Higher adsorption was obtained, around 80% of the loaded nisin and successful intercalation was verified by X-ray diffraction. The in-vitro release tests of the nisin from the biohybrid formulation was held over 25days in PBS medium (0.01M, pH7,4) and showed that no burst release phenomenon occurred at the beginning step, in addition, a sustained-time release of nisin was obtained compared with the free nisin. Therefore, these preliminary results are encouraging for the development of bioprotectors based on nisin intercalated LDH and being implemented in the food and medical industries.

Improving ham shelf life with a polyhydroxybutyrate/polycaprolactone biodegradable film activated with nisin

Abstract Environmental polution and food shelf life extension are issues of global concern. In this work, biodegradable Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) films and organo-clays (Cloisite ® 30 B and 10A) based nanocomposites were prepared. Tensile and thermal properties, water vapor barrier and activation with nisin were studied. Organo-clays addition promoted a reinforcement effect of the polymer blend, increasing barrier properties and degradation temperature. The optimal parameters for nisin adsorption to PHB/PCL film were 4000 IU cm −3 , 40 °C and 10 min. Organo-clays exerted antimicrobial activity against Lactobacillus plantarum CRL691; nevertheless, their inclusion into the polymer blend did not lead to antimicrobial films. Nisin adsorption to PHB/PCL film was not afected by clays presence. PHB/PCL nisin activated film was effective against L. plantarum CRL691 (used as processed meat spoilage bacterium model) inoculated on sliced ham, thus extending its shelf life. PHB/PCL blend and its nanocomposites activated with nisin showed potential for their application in processed meat packaging.

Emulsion Stabilized with Starch Octenyl Succinate Prolongs Nisin Activity Against Listeria Monocytogenes in a Cantaloupe Juice Model.

Food safety related to fresh and fresh-cut produce, such as cantaloupe, is a great challenge in the food industry. Various processing technologies, including the use of antimicrobial materials, have been applied to reduce pathogens. Nisin, an antimicrobial peptide, shows strong inhibitory activity against Listeria monocytogenes (LM); however, it suffers from quick depletion in foods. In this study, the protective effect of starch octenyl succinate (starch-OS) stabilized emulsion on nisin was evaluated in a cantaloupe juice model. Results showed that the proteolytic enzyme in cantaloupe juice caused nisin depletion, and the adsorption of nisin in emulsion led to considerable protection of antimicrobial activity. After 1, 3, and 6 d of incorporation with cantaloupe juice, the size of LM inhibitory ring were 7.64, 7.60, and 2.97 mm, respectively for emulsion formulations, whereas it reduced from 3.60 mm to a negligible level for nisin-alone. This study showed the potential of using carbohydrate colloidal systems to prolong the efficacy of antimicrobial materials.

Nisin Adsorption in Colloidal Systems Formed with Phytoglycogen Octenyl Succinate

While antimicrobial compounds are often used against food pathogens, they are liable to quick degradations in foods. One way to achieve their sustained efficacy is through the use of protective delivery systems. The overall goal of this study was to understand the interactions between nisin, an antimicrobial peptide, and phytoglycogen octenyl succinate (PG-OS), a dendrimer-like amphiphilic carbohydrate polymer in aqueous (non-emulsion) and emulsion based colloidal systems. Nisin interacts with PG-OS particulates following a Langmuir monolayer adsorption pattern in both systems. The monolayer adsorption capacity (Qm) ranged from 37.6 to 106.4 μg/mL in non-emulsion, and was 181.8 μg/mL in PG-OS stabilized emulsion. At the same doses of PG-OS (5.0 mg/mL) and nisin (200 μg/mL), the concentration of adsorbed nisin in emulsion and non-emulsion were 157 and 22 μg/mL, respectively. This study showed that both the chemical nature and physical distribution of PG-OS particulates would affect nisin adsorption, which may provide a method for designing carbohydrate colloidal systems to achieve effective protection of antimicrobial compounds for foods.

Adsorption of Nisin on Montmorillonite: A Concentration Strategy

The adsorption of a commercial form of nisin, Nisaplin® (Npl) (Danisco), on montmorillonite (Mt), a natural inexpensive clay mineral accepted as food additive, was assayed. The intention was to develop food grade materials capable of releasing the peptide and avoiding negative interactions that affect nisin antimicrobial activity in food environments. A set of different Mt-Npl relation samples was prepared. The antimicrobial activity and the total organic carbon/total nitrogen (TOC/TN) content measured in nisin solutions after contact with the clay decreased as the amount of solid increased; thus, indicating the adsorption of the peptide on the support. Also, the Mt-Npl solids presented inhibitory activity against Enterococcus faecium C1. Additionally, Fourier Transform-Infrared Attenuated Total Reflectance spectroscopy (FT-IR-ATR) analysis of the Mt-Npl lyophilised systems showed that nisin was preferably adsorbed on Mt among Nisaplin® ingredients, suggesting a unique concentration and immobilization method for this antimicrobial peptide that could be applied in food preservation. Practical Applications Montmorillonite (Mt) is an inexpensive abundant natural clay characterized by a moderate cation exchange capacity with high surface area. Nisaplin® is a commercial form of nisin, a polypeptide bacteriocin active against several Gram-positive food spoilage and pathogen microorganisms. The increasing demand for fresh and natural food favors the application of biopreservatives such as nisin. However, the interaction of these antimicrobials with other food components reduces their inhibitory effect when directly introduced into food systems. Thus, alternatives for the inclusion of active biomolecules in foods are necessary. Since Mt is a potential food additive, its use as a nisin immobilization agent provides a strategy to protect and optimize the gradual peptide liberation. This immobilization approach does not only offer a simple, rapid, and low cost method for the concentration of nisin, but also provides a feasible alternative procedure for the introduction of this antimicrobial peptide in food complex systems.

Optimization of cold nitrogen plasma surface modification process for setting up antimicrobial low density polyethylene films

In order to prevent microbial contamination and food-borne illnesses, antimicrobial active packaging represents an innovative option. The aim of this paper was to optimize the experimental parameters of the plasma treatment. Such pre-treatment can be used to develop an active packaging film by adsorbing a natural antimicrobial peptide “Nisin” on the surface of a commonly used polymer in the agro-food sector “low density polyethylene (LDPE)”. Cold nitrogen (N2) plasma treatment was used to functionalize LDPE and generate a hydrophilic polymer suitable for the adsorption of the peptide. The experimental design technique allowed determining the optimal conditions of the plasma treatment. The lowest contact angle and highest hydrophilic character were obtained for a gas flow rate of 500cm3/min, a generator power of 300W and an exposure time of 300s. The surface characterization techniques X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), contact angle and surface free energy measurements were used to confirm the surface modification after cold plasma treatment. The antimicrobial tests permitted to validate the efficiency of the active packaging films. The plasma treated films showed higher antimicrobial activity after nisin adsorption as compared to the native ones.

Adsorption of nisin and pediocin on nanoclays

Three different nanoclays (bentonite, octadecylamine-modified montmorillonite and halloysite) were studied as potential carriers for the antimicrobial peptides nisin and pediocin. Adsorption occurred from peptide solutions in contact with nanoclays at room temperature. Higher adsorption of nisin and pediocin was obtained on bentonite. The antimicrobial activity of the resultant bacteriocin-nanoclay systems was analyzed using skimmed milk agar as food simulant and the largest inhibition zones were observed against Gram-positive bacteria for halloysite samples. Bacteriocins were intercalated into the interlayer space of montmorillonites as deduced from the increase of the basal spacing measured by X-ray diffraction (XRD) assay. Infrared spectroscopy suggested non-electrostatic interactions, such as hydrogen bonding between siloxane groups from clays and peptide molecules. Transmission electron microscopy did not show any alteration in morphologies after adsorption of antimicrobial peptides on bentonite and halloysite. These results indicate that nanoclays, especially halloysite, are suitable nanocarriers for nisin and pediocin adsorption.

Antimicrobial nanocomposite films made of poly(lactic acid)-cellulose nanocrystals (PLA-CNC) in food applications: part A—effect of nisin release on the inactivation of Listeria monocytogenes in ham

New bioactive nanocomposite films were prepared by compression molding method for food applications. Film matrix was composed of poly(lactic acid) containing cellulose nanocrystals (PLA-CNC). Nanocomposite films were converted to bioactive films using nisin as an antimicrobial agent by an adsorption coating method. Resulting antimicrobial films were then introduced in packages containing sliced cooked ham as a food model and stored for 14 days at 4 °C to determine their inhibiting capacity against Listeria monocytogenes and their physicochemical and structural properties. The study also focused on the nisin release from the films by using an agar diffusion bioassay. It was observed that mechanical properties such as tensile strength, tensile modulus, elongation at break and water vapor permeability values of the bioactive films were stable after 14 days of storage. Fourier transform infrared spectroscopy analysis allowed characterizing the adsorption of nisin onto PLA-CNC surface. Microbiological analysis of sliced cooked ham inoculated with L. monocytogenes (3 log CFU/g) allowed determining the potentiality of nisin as a strong antimicrobial agent in PLA-CNC-based films. Bioactive PLA-CNC-nisin films showed a significant reduction of L. monocytogenes in ham from day 1 and a total inhibition from day 3. The percentage of nisin release increased continuously from day 0 to day 14, up to 21 % at day 14. These results demonstrated the potential application of PLA-CNC-nisin films on controlling the growth of food pathogens in meat products.

Study on the process of fermentation coupling with foam fractionation and membrane module for nisin production

ABSTRACTNisin, an antimicrobial peptide, is commercially used as a food preservative and a promising alternative in medical applications for inhibiting bacterial infection in both humans and livestock. It is produced by fermentation using certain strains of Lactococcus lactis ssp. lactis. In traditional fermentation, the yield of nisin has always been limited by adsorption of nisin onto its producer, enzymatic degradation and product inhibition. This limitation can be solved by fast removal of the product from the broth during fermentation. In the current work, a technology of fermentation coupling with foam fractionation and membrane module was developed to achieve in situ removal of nisin produced by L. lactis ssp. lactis ATCC 11454 from the broth. The effects of air flow rate, the initial aeration time and interval time on the performance of the technology were studied to increase the yield of nisin. The results showed that under the optimal conditions of air flow rate 60 mL/min, the initial aeration time of the fourth hour and regular 30‐min interval, the total nisin titer reached 3946 IU/mL, increased by 24.2%, compared with the control group (3177 IU/mL). Therefore the coupling technology can effectively weaken the feedback inhibition and thus increase the yield of nisin by in situ fast removal of the product from broth during fermentation. © 2014 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Adsorption of nisin on raw montmorillonite

The aim of the present work was to develop food-grade materials capable of releasing antimicrobial agents. Montmorillonite (Mt), a raw, abundant inexpensive clay mineral approved as a food additive, was used as support material. The immobilized antimicrobial agent was pure nisin (Danisco, UK). A series of antibacterial compounds were prepared, and the antimicrobial activity of the resultant montmorillonite–nisin (MtNis) immobilized systems was determined against Enterococcus faecium C1. The characterization of the antimicrobial powders showed evidences of nisin adsorption on by means of a “frustrated intercalation” model with a nisin loading (NL) saturation value close to 0.24CEC (cation exchange capacity) of Mt. The antibacterial powders with NL above this value completely inhibited E. faecium C1 during 24h of contact. These results are encouraging for the development of nisin-based bioprotectors immobilized on raw Mt.