Hướng Dẫn Is Listeria a bacteria virus parasite or fungi? Mới nhất 2022

Thủ Thuật Hướng dẫn Is Listeria a bacteria virus parasite or fungi? Mới nhất Chi Tiết

Bạn đang tìm kiếm từ khóa Is Listeria a bacteria virus parasite or fungi? Mới nhất được Cập Nhật vào lúc : 2022-12-07 01:40:00 . Với phương châm chia sẻ Kinh Nghiệm Hướng dẫn trong nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi Read nội dung bài viết vẫn ko hiểu thì hoàn toàn có thể lại phản hồi ở cuối bài để Tác giả lý giải và hướng dẫn lại nha.

Thủ Thuật Hướng dẫn Is Listeria a bacteria virus parasite or fungi? Chi Tiết

Quý khách đang tìm kiếm từ khóa Is Listeria a bacteria virus parasite or fungi? được Cập Nhật vào lúc : 2022-12-07 01:40:08 . Với phương châm chia sẻ Bí quyết về trong nội dung nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi Read nội dung nội dung bài viết vẫn ko hiểu thì hoàn toàn hoàn toàn có thể lại phản hồi ở cuối bài để Mình lý giải và hướng dẫn lại nha.

Bioactive Natural Products (Part K)

Takashi Hasegawa, … Yasunobu Yoshikai, in Studies in Natural Products Chemistry, 2005

Nội dung chính

Bioactive Natural Products (Part K)Augmentation of the host defense against Listeria infection with normal or murine leukemia viruses, LP-BM5 MuLV infected-immunocompromissed mice by hot water extracts (CVE) administrationAntibiotics Derived From Marine OrganismsProtein/PolypeptideMilk as a Natural Product: Foreign Natural and Anthropogenic Organic Compounds in ItMicrobial Populations in CheeseChemistry and Bioactivities of Royal JellyAntimicrobial ActivitiesFood Packaging: Surface Engineering and Commercialization11.4.1 Surface Engineering Concept for the Application in Food PackagingNanostructured Multilayer Films6.3.3 Other TechniquesBioactive Components from Leaf Vegetable ProductsNew Perspectives and Potential Applications of Leaf Vegetable ProductsMilk Fat Globule Membrane MaterialHealth-Beneficial Properties of MFGM PLsVideo liên quan

We have shown that oral administration with hot water extracts (CVE) significantly augmented the host defense against infection with Listeria monocytogenes (L.monocytogenes) [10]. L.monocytogenes is one of an intracellular bacteria, as well as Mycobacterium tuberculosis [1112]. The protective mechanism against Listeria infection depends mainly on the immune response mediated by αβ T cells [13].

We have recently reported that γδ T cells precede αβ T cells in appearance in the peritoneal cavity during Listeria infection and play an important role in protection the early stage after listerial infection [1416]. We found that CVE augmented the host defense against Listeria infection by augmenting cell-mediated immunity the early stage after infection.

The FCM analysis using mAbs to Thy1.2 and γδ TCR was carried out on the nonadherent population of the PEC in normal mice and CVE-administered mice the early stage after an i.p… infection with L.monocytogenes (Fig.(2)). Consistent with our previous reports, γδ T cells increased in the PEC of control mice on day 3 and on day 5 after Listeria infection. The increment of the proportion of γδ T cells in the PEC of CVE-administered mice infected with L.monocytogenes was significantly higher than that seen in untreated control mice.

Figure 2. γδ T cells in nonadherent PEC obtained from CVE-administered mice after i.p… inoculation with L.monocytogenes. Nonadherent PEC obtained various times after infection with L.monocytogenes were stained with anti-TCRαβ, anti-PE-Thy1.2, followed by goat anti-hamstar FITC-IgG, or anti-Bio-TCRγδ, anti-PE-Thy1.2, followed by Streptavidin FITC. *: Significantly different from the value for the control group, P<0.05).

In order to compare the development of Listeria-specific cell-mediated immunity between the CVE-administered group and the control group, we examined DTH response using heat-killed L.monocytogenes as the eliciting antigens. As shown in Figure (3), the DTH response of CVE-administered mice in the early stage of infection on day 6 was significantly higher than that of the control mice. Afterward, DTH response of CVE-administered mice maintained a constant level on day 12 after infection. These results suggested that CVE administration effectively augment cell-mediated immunity in correlation with an increase of γδ T cells the early phase of Listeria infection. CVE administration augmented DTH response from the early stage to the late stage after infection.

Figure 3. The kinetics of DTH responses of CVE-administered mice infected with L.monocytogenes. The DTH response was determined 6 or 12 days after an i.p… injection of a sublethal dose (1×104/a) of L.monocytogenes. Mice were injected 1.6×108 heat-killed Listeria cells in 50 μl of pyrogen-không lấy phí PBS into the right footpad. The left footpad of each mouse received an equal volume of PBS. Twenty-four hours later the thickness of each footpad was measured using a dialgauge micrometer. Data values are expressed as means±standard deviation (n=6). *: Significantly different from the value for the control group, P<0.05).

Increase in number of CD4+ T cells in CVE-administered mice the late phase after infection may be due mainly to Th2 cells (data not shown). Alternatively, the increment of DTH response seems to be closely correlated with an increase of γδ T cells in CVE-administered mice the early phase of infection. It is suggested that γδ T cells may be directly or indirectly associated with the strong DTH response appearing the early stage after infection.

CVE has been shown to be a potent host-mediated immuno-modulator by augmenting the production of a cytokine/cell growth factor, such as GM-CSF, and/or the responsiveness of the progenitor to CSF [17]. In conclusion, oral administration of CVE augments the resistance against listerial infection via the early development of cell-mediated immunity to Listeria.

Murine leukemia virus LP-BM5 MuLV is known to induce a remarkable immunodeficiency syndrome in C57BL/6 mice [18]. The syndrome caused by this virus is called murine acquired immunodeficiency syndrome (MAIDS). This virus also causes an early selective defect in CD4+ Th-cell function, and some whose symptoms are similar to those found in AIDS patients [19]. MAIDS mice are a useful model for elucidating the mechanism of depressed resistance to opportunistic pathogens common in AIDS patients [2021].

The therapeutic potential of CVE against Listeria resistance in an immunocompromised host has been evaluated [22]. In this report, we found that the protection against the late phase of Listeria infection is impaired in MAIDS mice, and the numbers of bacteria in target organs in CVE-treated MAIDS mice were lower than those in MAIDS mice the late phase after Listeria infection (Fig. (4)).

Figure 4. Effect of oral administration of CVE on the growth of L.monocytogenes in the spleen of LP-BM5-infected mice. Mice were infected with 0.1ml of LP-BM5 intraperitoneally and were challenged with L.monocytogenes (2×104) on week 4 after LP-BM5 infection. Two percent CVE-containing solid chows were given to the mice infected with LP-BM5 on week 2 and were given until the experiments were over. Data values are representative of two experiments (n=5). *: Significantly different from the value for the control group, P<0.05.

The listerial number in target organs were eliminated completely in CVE-treated MAIDS mice on day 10 after listerial infection, whereas Listeria in the spleen and peritoneal cavity were still detectable in MAIDS mice on day 10 after listerial infection. Thus, the difference between CVE-treated MAIDS mice and MAIDS mice was most noticeable on day 10 after listerial infection.

It has been reported that DTH response results in swelling and a predominantly mononuclear cell infiltration the injection site [23].

Figure 5. The kinetics of DTH responses of CVE-administered mice infected with L.monocytogenes. Mice were infected with 0.1ml of LP-BM5 intraperitoneally and were challenged with L.monocytogenes (2×104) on week 4. Two percent CVE-containing solid chows were given to the mice infected with LP-BM5 on week 2 and were given until the experiments were over. The DTH response was determined on day 7 after an injection of sublethal dose (2×104) of L.monocytogenes. Mice were injected 1.6×108 heat-killed Listeria cells in 50 μl of pyrogen-không lấy phí PBS into right footpad. The left footpad of each mouse received an equal volume of PBS. Twenty-four hours later, the thickness of each footpad was measured using a dialgauge micrometer. Data values are representative of two experiments and are expressed as means±standard deviation (n=8). *: Significantly different from the value for the control group, P<0.05.

The DTH response to Listeria antigen in CVE-treated MAIDS mice was significantly higher than that of MAIDS mice on day 7 after Listeria infection, although the response was much lower than in normal mice.

DTH response can be partially ascribed to the production of IFNγ by Th2 cells in response to the antigen [23]. IL-12 released from macrophages is reported to stimulate NK and Th2 cells to produce IFNγ [24]. We speculated that CVE administration augments IFNγ secretion through the activation of macrophages to produce several monokines including IL-12 and to consequently restore the response to the presentation of Listeria-specific antigens.

Next, in order to elucidate the mechanism whereby CVE augments the immune response against L.monocytogenes, we examined the effects of oral administration of CVE on the expression of mRNA specific for various cytokines in the adherent cells of normal mice and MAIDS mice infected with L.monocytogenes.

Figure 6. RT-PCR analysis of cytokine mRNA expression in the adherent PEC of mice given CVE. Two percent CVE-containing solid chows were given to mice two weeks previously. Total RNAs were extracted from adherent PEC and reverse-transcribed, and the cDNA concentration was adjusted by co-amplification of twofold serially diluted cDNA and constant amounts of control plasmid pMCQ with β-actin-specific primers. Cytokine mRNA expression patterns of IL-1α, TNFα, MIP, IL-12 and GM-CSF were determined by PCR using murine cytokine-specific primers, respectively. The PCR products were separated in 2 % agarose gel and visualized by ethidium bromide staining. Relative quantification of the amounts of the RT-PCR products was performed using a Computing Densitometer and MasterScansoftware. The signal intensity is presented as the relative value to the maximal optical density (OD) of each cytokine. The value the bottom of each column indicates net OD measured by a Computing Densitometer and MasterScan software.

Figure 7. RT-PCR analysis of cytokine mRNA expression in the spleens of normal mice or MAIDS mice infected with L monocytogenes. Two percent of CVE-containing solid chows were given to the normal mice or mice infected with LP-BM5 two weeks previously and 2 weeks later, 2×104 L.monocytogenes were inoculated i.p… into both mice groups. Total RNAs were extracted from spleens of the mice of both groups on day 6 after Listeria infection using RNAzol and reverse-transcribed, and the cDNA concentration was adjusted by co-amplification of twofold serially diluted cDNA and constant amounts of control plasmid pMCQ with β-actin-specific primers. Cytokine expression patterns of IL-12, IFNγ, and IL-10 were determined by PCR using murine cytokine-specific primers, respectively. Relative quantification of the amounts of the RT-PCR products was performed using a Computing Densitometer and MasterScan software. The signal intensity is presented as the relative value to the maximal OD of each cytokine. The value the bottom of each column indicates net OD measured using a Computing Densitometer and MasterScan software.

1, uninfected mice; 2, mice infected with L.monocytogenes; 3, mice given CVE and infected with L.monocytogenes; 4, MAIDS mice infected with L.monocytogenes; 5, MAIDS mice given CVE and infected with L.monocytogenes.

The results were as follows:

(1)

Significant increases in expressions of IL-12 and TNFα mRNAs were detected in the peritoneal adherent cells in normal mice after oral administration of CVE.

(2)

The expression levels of IL-12 and IFNγ mRNAs were augmented in the spleen of normal mice after infection with L.monocytogenes by CVE administration.

(3)

Oral administration of CVE increased the expression levels of IL-12 and IFNγ mRNAs but rather reduced the IL-10 mRNA level in the spleen of MAIDS mice after infection with L.monocytogenes.

In conclusion, we demonstrated that oral administration of CVE was related to the retention of the capacity of MAIDS mice to eliminate L.monocytogenes in association with an improvement in the defective immune response to L.monocytogenes. CVE treatment enhances the host defense against opportunistic Listeria infection in immunodeficient mice. Furthermore, we have obtained evidence that oral administration of CVE augments the levels of IL-1α, TNFα and IL-12 mRNA expressions in macrophages. It also augmented the levels of IFNγ mRNA in the spleen of normal mice and MAIDS mice after infection with Listeria. CVE may induce Th2-biased immune responses via activation of macrophages and enhance the resistance to L.monocytogenes infection in normal and MAIDS mice.

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Antibiotics Derived From Marine Organisms

Bibi Nazia Auckloo, Bin Wu, in Studies in Natural Products Chemistry, 2022

Protein/Polypeptide

The Lactococcus lactis strain PSY2 isolated from the surface of marine yellow perch fish Perca flavescens exhibited antibacterial activities against gram-positive and gram-negative bacteria namely Arthrobacter sp., Acinetobacter sp., Bacillus subtilis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus. It was seen that the shelf-life of the reef cod fillet, Epinephelus diacanthus was extended to greater than 21d 4°C upon spraying 2.0mL of 1600AU/mL bacteriocin on the latter compared to the short lifetime of the control (less than 14d). Therefore, the bacteriocin PSY2 which was confirmed as a protein due to its inactivity against trypsin treatment acted as an antibiotic which could be utilized for the preservation of high-cost seafood [75].

A new compound designated as Hc-cathelicidin (Hc-CATH) comprising of 30 amino acids was the first cathelicidin to be isolated from the sea snake Hydrophis cyanocinctus. It was seen to exhibit powerful antimicrobial activities by dislocating the pathogen’s cell membrane thus killing the bacterial cells. Low cytotoxicity against mammalian cells was also observed making it a good candidate for further development as an antibiotic [76].

Crassostrea madrasensis, an edible oyster found in India, generated a protein with bacterial inhibitory capacities against various human pathogens namely Vibrio parahaemolyticus, Streptococcus sp., and Staphylococcus sp. in the agar well diffusion assay with minimum inhibitory concentration (MIC) being greater than 0.1mL [77].

A new compound namely Myticusin-1 was isolated from hemolymph of adult mussels M.coruscus in Zhoushan, China. Myticusin-1 is an 11kDa peptide (104 amino acids) including 10 cysteines forming five disulfide bonds, and 30 residues N terminal sequence, where its tertiary configuration was principally categorized by alpha-helixes. Myticusin-1 was proven to exhibit resilient antibacterial activities against gram-positive strains namely B.subtilis, S.aureus, Sarcina luteus, and Bacillus megaterium (MIC10mM). This compound was perceived to act on the cell wall of both S.luteus and E.coli where laminar mesosomes were seen to appear followed by cell wall effects including unevenness of its thickness as well as the separation of the cytoplasmic membrane from the cell wall [32].

Hormaomycin B and C (Fig.10.1) from a marine mudflat-derived actinomycete strain (SNM55) were isolated from Mohang, Korea. Hormaomycin B and C were peptide-derived compounds with highly modified amino acid residues. The two cyclic depsipeptides possessed distinctive structural units, namely 4-(Z)-propenylproline, 3-(2-nitrocyclopropyl) alanine, 5-chloro-1-hydroxypyrrol-2-carboxylic acid, and β-methylphenylalanine. Both were shown to possess substantial inhibitory properties against pathogenic bacterial strains Kocuria rhizophila NBRC 12,708 [69].

Figure10.1. Structures of antibiotics in protein/polypeptide class.

Another depsipeptide called etamycin (Fig.10.1) was for the first time isolated from an actinomycete strain (CNS-575) from Nasese shoreline, Viti Levu, Fiji. The structure of etamycin was certified as a three distinct rotamer appearing in the 2D nuclear magnetic resonance spectrum. Etamycin, belonging to the streptogramin antibiotic class, was shown to have potential antibacterial activities against a range of clinically relevant hospital-associated and community-associated methicillin-resistant S.aureus (HA- and CA-MRSA) where the MIC was only 12mg/L. In addition, gram-positive bacteria namely Streptococcus pyogenes and Streptococcus agalactiae as well as Gram-negative bacteria such as coccobacilli and Moraxella catarrhalis were also affected by etamycin which furthermore showed no cytotoxity even 128mg/L. Etamycin exhibited promising time-kill kinetics in comparison to vancomycin (another MRSA antibiotic) as well as exposed its ability to prevent death in a murine model of systemic lethal MRSA infection. Etamycin, alone, was seen to be prominent in the obstruction of protein synthesis in bacterial cells as compared to other streptogramin antibiotic [quinupristin-dalfopristin (Synercid): presently used in complex cutaneous infections] which are only able to act in pairs where quinupristin bind to 50S ribosomal subunit averting polypeptide elongation and dalfopristin enhance the latter’s activity by binding to another site on the 50S ribosomal subunit in order to inhibit protein synthesis [78].

Neamphamide B (Fig.10.1), a cycle depsipeptide, was isolated from the marine sponge Neamphius sp. in Nhật bản. Neamphamide B possessed antimycobacterial abilities against Mycobacterium smegmatis MIC 1.56μg/mL under both aerobic and hypoxic conditions. Furthermore, it was also proven active against Mycobacterium bovis Bacillus Calmette-Guérin (BCG) with MIC values 6.2512.5μg/Ml making it a good antimycobacterial agent [79].

A new cationic compound comprising of three positively charged amino acids (one histidine and two lysine) and one negatively charged amino acid (aspartic acid) having approximately 50% of hydrophobic amino acid content was designated as myxinidin. It was isolated from the acidic epidermal mucus of the hagfish M.glutinosa L. found in Canada. A wide range of pathogenic bacteria such as Salmonella enterica serovar Typhimurium C610, E.coli D31, Aeromonas salmonicida A449, Yersinia ruckeri 96-4, and Listonella anguillarum 0211 was tested against myxinidin where the latter was highly dominant the minimum bactericidal concentration 1.02.5μg/mL. It was further noted that myxinidin was able to preserve its antibacterial capacities in elevated sodium chloride concentration (up to 0.3M) as well as showed no hemolytic activities against mammalian blood cells. Myxinidin was also exposed to be 16 times stronger than pleurocidin NRC-17 (another antimicrobial peptide) against the tested pathogenic microorganisms [33]. Additional studies suggested that this type of compound had the ability to disrupt the cytoplasmic membrane [80] or the restriction of nucleic acid synthesis [81].

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Milk as a Natural Product: Foreign Natural and Anthropogenic Organic Compounds in It

Miguel E. Alonso-Amelot, in Studies in Natural Products Chemistry, 2022

Microbial Populations in Cheese

High moisture cheese (>50% moisture content) may harbor pathogens from milk despite the lactic acid maturation process, with consequences to consumer risk according to the 2022 recollection of Choi and coworkers [163]. Besides occasional infestation with S. aureus and Escherichia coli, Listeria monocytogenes emerges as one of the best studied cheese bacterium [164]. Listeria survives in lactic and enteric truyền thông. Lactic acid starters may retard L. monocytogenes growth but do not inhibit it completely. The bacterium can replicate under low moisture and high salt environments. In cheese making, Listeria is concentrated in the curd leaving only a small fraction in whey. Once in the caseinate curd, bacterial populations expand depending on the ripening process, cheese type, and lactic bacterial community. Listeria is able to multiply in large numbers during the later stages of ripening of soft cheeses including world famous Camembert [165,166]. Prevalence of Listeria in cheese sold in open air markets and stores in western European countries varies from zero (from pasteurized milk) to 65% (from raw milk) averaging 14.2%, according to surveys of 4800 samples [161].

Outbreaks of milk and cheese-borne enterocolitis involving S. aureus, L. monocytogenes, pathogenic E. coli strains, and Salmonella spp. very low doses are reported in many parts of the world, with several deaths in some cases [167170]. In the European Union countries (2006), however, a moderate 0.4% of all food-borne poisoning outbreaks was related to consumption of cheese in substandard conditions, particularly fresh cheeses [161]. While standard pasteurization does not correct this problem [171], novel processing techniques including UHT (ultra-high temperature processing), high pressure, and membrane technologies improve 21st century perspectives of dairy product sanitation [172,173].

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Chemistry and Bioactivities of Royal Jelly

Eleni Melliou, Ioanna Chinou, in Studies in Natural Products Chemistry, 2014

Antimicrobial Activities

A peptide fraction was isolated from RJ, where the N-terminal amino acid sequence of the major peptide within the fraction was VTCDLLSFKG. This sequence corresponded to the honeybee defensin royalisin of MW 5523Da that has been shown to exert antibacterial activity against some Gram-positive bacteria. Diffusion tests on agar plates showed that the peptide fraction had an inhibitory effect against the honeybee pathogen Paenibacillus larvae subsp. larvae, the primary pathogen of American foulbrood disease, as well as against other Gram-positive bacteria such as Bacillus subtilis and Sarcina lutea. Moreover, the peptide fraction was shown also to possess antifungal effect against the model fungus Botrytis cinerea [40]. Peptides isolated from natural fonts have been the object of several studies aimed finding new molecules possessing antibacterial activity. In a recent study on peptides, originally isolated from RJ, the jelleins, and some analogs having a UV reporter the N- or C-terminus, it was find out that they are mainly active against Gram-positive bacteria; interestingly, they act in synergy with peptides belonging to the family of temporins such as temporin A and temporin B against Staphylococcus aureus A170 and Listeria monocytogenes [41]. The antimicrobial activity of RJ’s peptide defensin 1 has been also published in another study where it was determined that it is able to inhibit in vitro growth of the pathogen causing American foulbrood (AFB) (P. larvae subsp. larvae) [42].

Greek RJ extracts of different polarities and their isolated compounds were studied for their antimicrobial activity against six Gram-negative and Gram-positive bacterial strains, two oral pathogens (S. mutans and S. viridans), and three human-pathogen fungi (C. albicans, C. tropicalis, and C. glabrata). The results of these tests showed interesting and promising antimicrobial activity as some of the isolated compounds such as 3-hydroxydodecanedioic acid exhibited very strong antimicrobial activity against all assayed microorganisms (MIC 0.170.36mg/mL). Methylparaben and 9-hydroxy-2-nonanone showed specific activity against S. aureus and S. epidermidis, while the higher activity against all assayed fungi was exhibited by sebacic acid (MIC 0.150.20mg/mL). It was noteworthy that both methanolic and dichloromethane extracts showed distinguished antimicrobial spectrum of activity [9,10].

RJ has been also studied for its in vitro and in vivo antimycotic activity against dermatophytes. The results of the in vivo studies showed an antimycotic activity against Epidermophyton floccosum, Microsporum canis, and Microsporum gypseum; while all tested strains of Trichophyton sp. appeared resistant even with the maximum assayed concentration [43].

Several honeybee products including RJ have been evaluated for their ability to inhibit the growth of 40 yeast strains of Candida albicans, Candida glabrata, Candida krusei, and Trichosporon spp. using the broth microdilution method. MIC values for RJ and fluconazole (used as standard) were 0.061 and 0.0296μg/mL, respectively, demonstrating that RJ could potentially control some fluconazole-resistant fungal strains [44]. 10-hydroxy-2-decenoic acid (10-HDA), main component of RJ, is well known for its antimicrobial properties [9,10]. Streptococcus mutans associated with pathogenesis of oral cavity, gingivoperiodontal diseases, and bacteremia following dental manipulations, while the genes that encode glucosyltransferases (gtfs) especially gtfB and gtfC are important in S. mutans colonization and pathogenesis. In a recent study, it was proved that 10-HDA prevents gtfB and gtfC expression efficiently in the bactericide subconcentrations and it could effectively reduce S. mutans adherence to the cell surfaces [45].

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Food Packaging: Surface Engineering and Commercialization

Sibu C. Padmanabhan, … Michael A. Morris, in Nanomaterials for Food Packaging, 2022

11.4.1 Surface Engineering Concept for the Application in Food Packaging

Recent developments show an increased focus on active food packaging concepts based on surface engineering of polymers or surface coating deposition of AM agents on film surfaces. The main advantage of this concept was the envisaged quick availability of AMs from the direct contact layer inside of the food package. This concept can be particularly useful considering the comparatively higher moisture content and other favorable atmospheric conditions the food product surface that may facilitate AM growth. A provision for on-demand AM delivery by the direct contact surface was proposed to be the ideal technology to address this issue. In an attempt to compare the efficacy of AM surface coating with bulk impregnated AM, Ha et al. prepared grapefruit seed extract (GFSE) incorporated PE films by both coextrusion and a solution coating process and assessed their feasibility against the growth of microorganisms such as Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Mucilaginibacter flavus in ground beef [55]. They found that both types of AM films reduced the growth rates of bacteria on ground beef stored 3°C, as compared with plain PE film; however, the coating resulted in a higher level of AM activity than the coextruded film. The coextruded film (15μm thick) with 1.0% (w/w) grapefruit seed extract showed AM activity against M. flavus only, whereas the coated film (43μm of LDPE with 3μm of coating layer) with 1.0% (w/w) grapefruit seed extract showed activity against E. coli, S. aureus, and B. subtilis.

They prepared the GFSE coating (0.5% or 1%) with the aid of a 40% polyamide binder (Versamid 750) in 2:1 isopropanol/n-propanol by a spread coating method after a corona pretreatment of the LDPE substrate. Cooksey has shown the inhibitory effect of nisin coated onto LDPE film, using a cellulose-based coating method, against the growth of S. aureus and Listeria monocytogenes in a nonfood system [64].

Cerisuelo et al. has prepared carvacrol, citral, marjoram essential oil, or cinnamon bark essential oil incorporated surface coatings on PP and PET substrates by using a polyethyleneimine anchor and ethylene vinyl alcohol (EVOH) matrix [36]. They showed that a corona discharge followed by polyethyleneimine primer coating was effective in depositing AM-incorporated EVOH. They also showed the effectiveness of bentonite nanoclay in improving the physical properties of coated films on incorporation into the EVOH matrix.

AM coatings on plastic substrates were also prepared by chemical vapor deposition from alcoholic solutions of metal nitrates such as silver, copper, and zinc [65]. Another type of AM coating prepared by using zein as the binder and ethanol as carrier and a metal- or nonmetal-doped TiO2 as the active materials was patented [66]. Schroeder and Scales patented charged organic molecule-based AM coatings on plastics [67]. The coating was obtained by covalently bonding quaternary ammonium and phosphonium salts onto a polymeric material.

Though a large number of studies have been reported on surface engineering and surface coating-based methods, their commercialization has been limited by the availability of silver and consequent migration (to the food) related regulatory issues. The direct contact of silver coatings (as films or nanoparticles, etc.) and the food makes these technologies somewhat less preferable by the industry and the technologies are not well developed an industrial level. However, continued research efforts and developments are ongoing to address this shortcoming. Intensive research is focused on maximizing the antimicrobial capacity of surface-coated functionalities with a minimum possible surface concentration.

Recently, Morris, Kerry, and coworkers have demonstrated the in vitro antimicrobial potential of surface-engineered silver-based antimicrobials against Gram-positive (S. aureus) and Gram-negative (Pseudomonas fluorescens) bacteria. They have then demonstrated the in vivo antimicrobial activity of novel packaging materials developed by a surface coating technique and shown shelf life extension of skin packaged chicken breast fillets under chilled (4°C) storage conditions [68]. Their surface engineering concept was based around a block copolymer (BCP) assisted deposition of silver ions in nanocavities formed by self-assembly driven phase separation of the BCP under suitable conditions [69]. This simple technique allows direct deposition of materials and functionalities onto a range of substrates. Self-assembly is a process of self-organization of materials or components into patterns or structures without the assistance of any external forces or manipulation. BCPs are made of two or more chemically distinct polymer blocks within a single molecule. The minimum energy arrangement of blocks within the bulk or a surface film is when the component blocks are separated to their maximum extent and share their interfaces to the minimum possible extent. The presence of the covalent linkage in the middle, however, keeps the blocks still connected restricting their separation, thereby causing them to freeze within a phase-separated nanoscale structure.

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Nanostructured Multilayer Films

Miguel A. Cerqueira, … Jose M. Lagaron, in Nanomaterials for Food Packaging, 2022

6.3.3 Other Techniques

Several strategies have been presented for the formation of mono- or multilayers in a packaging material, being lamination, coating, and coextrusion the most used techniques in packaging industry. So far, it seems that the use of these techniques in their current stage is not able to produce nanostructured multilayer films, but recent developments have showed the possibility of producing multilayer systems with nano-sized layers using coating techniques and coextrusion [94,95].

Several studies the laboratory scale have showed the possibility of using coating techniques for the formation of multilayer systems. One of the simplest process, which is widely used the laboratory, is to add the coating solutions to the surface of interest and leave it to dry. Several devices (e.g., Bird-Type Film Applicators and manual K-Hand Coater) have been developed to control the thickness of this films. Barbaro et al. [96] previously showed the possibility to develop a 7-μm PLA coating onto a biaxially oriented polyethylene terephthalate (BOPET) film, while Cinelli et al. [97] added a 10-μm WPI coating to a film made of a copolyester and PLA blend (BIO-FLEX, FKuR Kunststoff GmbH, Willich, Germany), leading to films with lower values of permeability to oxygen. This coating technique potentially allows the use of bio-based coatings as carriers of antimicrobial compounds and, therefore can be used for the production of active packaging materials. Some examples have been presented using proteins and polysaccharides. WPI-based coatings loaded with nisin have been applied in PP films and exhibited significant activity against the Lactobacillus plantarum growth [98]. Also, several coatings containing EOs have been applied in linear low-density polyethylene (LLDPE) using zein from corn as coating material [99]. Additionally, chitosan has been used as a carrier of EOs and used to coat PP films. These multilayers were tested against Listeria monocytogenes, S. aureus, and E. coli O157:H7 and it was found that the coated films present antimicrobial activity against these three bacteria [100]. Through a lamination process, Gherardi et al. [101] developed an antimicrobial packaging using a multilayer based on polyester, aluminum, and LDPE. In this case, the adhesive, a polyurethane (PU) không lấy phí of isocyanates with a thickness of ~3μm, contained an antimicrobial substance that was released from the packaging and decreased the microbial growth, then acting as an active packaging material. In particular, cinnamon EO showed the best results against Escherichia O157:H7 and Saccharomyces cerevisiae.

Recently, Tera-Barrier Films Pte Ltd. (Singapore, Singapore) presented a technology able to produce a multilayer nanoscale using slot-die coating. Using this technique, a liquid is forced out of a reservoir through a slot by pressure and transferred to the moving substrate, i.e., the film. In a previous study, multilayers were able to reduce the permeability through the deposition of a polymer layer with MNPs [62]. Another promising application of the slot-die coating is the use of a mixture of cellulose nanowhiskers (CNWs) and other nanoparticles as a coating. This technology was presented by Valentis Nanotech (Jerusalem, Israel), showing the possibility of coating different plastic films and improving the tensile elasticity of PE, biaxially oriented polypropylene (BOPP), and PET films in 118%, 22%, and 14%, respectively [102].

Lipids and waxes have been also extensively studied in the formation of coatings and multilayers [103,104]. Due to their hydrophobicity, they have been tested in hydrophilic materials, such as polysaccharide-based films. Recently, Slavutsky and Bertuzzi [94] showed the formation of a nanolayer on starch-based films that can be used to improve the barrier properties and decrease the hydrophobicity of the film. For the formation of the nanolayer, the starch film is dipped in an oil phase and then washed with hexane, resulting in the formation of a lipid-based nanolayer. Recently, in BIO4MAP, a European project that ended in 2022, it was shown the possibility of using candelilla wax in a multilayer system to improve the barrier properties of a multilayer packaging material against water vapor [105].

Another possibility for the production of multilayer systems the nanoscale is the multilayer coextrusion. This processing technique allows producing films with up to thousands of layers with layer thicknesses in both the micro- and nanoscale. Using this technology, polymers with different properties can be combined into multilayer structures with up to 4096 layers and an individual layer thicknesses <20nm [106]. It was possible to improve the barrier and mechanical properties of the polymer materials using this nanostructured multilayer. In 2010 Gupta et al. [95] showed the possibility of producing layers of a poly(propylene-grafted-maleic anhydride) (PP-g-MA) in which a phosphate glass (Pglass) was incorporated into alternating layers of PP-g-MA. The results showed a reduction in gas permeation for those materials with a higher number of layers and also with a higher content of Pglass. In another work, it was also observed that the number of layers had a great effect on the mechanical properties of the multilayer films based on polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Films with the same thickness but with different number of layers and layer thicknesses showed different properties and, as the layer thickness was reduced down to 31nm (4096 layers), the film presented higher stiffness and strength than other similar films with thicker layers [107]. One of the companies that explores this technology is PolymerPlus LLC (Valley View, Ohio, United States). In particular, they offer the possibility of using this technology for commercial packaging for different applications, including food packaging [105].

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Bioactive Components from Leaf Vegetable Products

Francisco J. Barba, … Ana Frígola, in Studies in Natural Products Chemistry, 2014

New Perspectives and Potential Applications of Leaf Vegetable Products

Leaf green vegetables are widely consumed and are prepared using various cooking methods. These products have been eaten for centuries and are classified as GRAS [78]. The use of leaf vegetable products as extracts or their derived forms in food and beverages is becoming an increasing trend in food industry as a potential source of bioactive compounds with antimicrobial and antioxidant properties.

Chemical and microbiological deteriorations are principal causes of quality loss of fish, meat, and their derived products during handling, processing, and storage. Lipid oxidation, microbial growth, changes of color and texture as lowering nutritional value of these products can be reduced by applying antioxidant and antimicrobial agents, leading to a retardation of spoilage, extension of shelf-life, and maintenance of quality and safety [79,80]. Many synthetic preservatives are typically used to protect foods from spoilage, although their use is restricted due to possible carcinogenic effects. Therefore, there has been increasing interest in alternative additives from natural sources, which has gradually provided impetus to eliminating synthetic preservatives in food [81].

Recently, it has been noticed a significant decrease of microbial population from ground beef patties during storage 4°C when natural chamnamul and fatsia leaf extracts were added, as well as with increased concentration of the extracts, and longer storage time [78]. In addition, the lipid oxidation (measured as TBARS, thiobarbituric acid reactive substances) of the ground beef patties with chamnamul and fatsia leaf extracts added was much lower than those of the control and remained almost unchanged over the storage period. Kim and Fung [82] evaluated the antimicrobial activity of water-soluble arrowroot tea extract against Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, Listeria monocytogenes, and Staphylococcus aureus in ground beef and mushroom soup. These authors found that the use of arrowroot tea inhibited the microbial growth of both gram-negative and gram-positive food-borne pathogens in various foods, especially liquid foods. In other research work, it was demonstrated that Majorana syriaca extract (obtained by ethyl acetate, containing polyphenols) added to mince tuna delayed the microbial growth (total viable count, Pseudomonas spp., and lactic acid bacteria) as compared with pure minced tuna. In the same study, it was also found that the antimicrobial effect increased as the concentration increased [83].

Polyphenols from leaf vegetable products can be also used to minimize oxidative reactions in other food products such as dairy products and fruit/vegetable juices. In this line, a research work published in 2012 studied the use of oregano extracts as a healthy alternative to omega-3 fatty acids in dairy beverages formulation, because these fatty acids are susceptible to oxidation. The oregano extract contained 269mg gallic acid equivalents per gram and was shown by the DPPH radical assay to have powerful antioxidant activity. They found that oregano extract can be used for preventing the formation of conjugated dienes, hexanal, and propanal as well as the depletion of oxygen induced by heat or light oxidation during 10 days storage. Moreover, they also found that the addition of oregano extract did not affect dairy beverage physical stability during storage [84].

Blending fruits, underutilized fruits, are vegetables with leaf products in appropriate proportions for the preparation of fruit and vegetable-based nutritive beverages. In this line, some authors have obtained an increase in β-carotene contents of spinach and pineapple juice blended with carrot juice. They also found a minimum (52.0261.41%) loss in β-carotene content during 6 months storage of juice blended with carrotspinach and carrotpineapple juice [85].

Tea, one of the most consumed beverages worldwide, is rich in bioactive compounds (flavonols and flavanols) with healthy properties and can be a useful tool in order to provide new food combinations with enhanced antioxidant, antimicrobial, anticarcinogenic, and anti-inflammatory properties. Numerous authors have concentrated on studies to evaluate the use of green tea extract in various food applications in order to increase healthy benefits of these. In this line, green tea extract was incorporated into bread as a source of tea catechins [86]. In addition, extra virgin olive oil was enriched with green tea polyphenols. This combination improved the beneficial antiatherogenic effects of extra virgin olive oil, leading to the attenuation of atherosclerosis development [87].

Moreover, green tea ( 250ppm) substantially reduced the oxidation process Atlantic mackerel (Scomber scombrus) stored for up to 26 weeks 10 or 80°C [88]. In this line, other research works have demonstrated that green tea extracts were more effective antioxidants in order to improve antioxidant properties of sucuk (Turkish dry-fermented sausage) during the ripening periods than synthetic antioxidants [89], and other authors obtained a strong inhibition of microbial growth and lipid oxidation of fresh pork sausages by using rosemary, borage, green tea, and pu-erh tea extracts during 20 days storage [90]. In addition, green tea extracts have been used in order to improve antioxidant properties of dehydrated apple products [91], to prevent the retrogradation of starch in rice starch products [92] and for slowing down the process of oxidation of fatty acids of biscuits [93].

More recently, other authors analyzed blended broccoli by-products (a good source of nitrogensulfur compounds (glucosinolates and isothiocyanates) and phenolics (chlorogenic and sinapic acid derivatives, and flavonoids), as well as essential nutrients (minerals and vitamins)) with green tea extracts. They found that the combination of green tea enriched with broccoli concentrates showed improved physical quality, phytochemical composition, and antioxidant capacity [94].

S. rebaudiana, an herb native from South America, is used as a natural sweetener and is thought to possess antioxidant, antimicrobial, and antifungal activity [95]. Although Stevia-derived products have been used in different countries for several years, in Europe they have not been used extensively. FDA approved Stevia for commercialization in 2008 (FDA GRAS 275 and 323) and more recently, in November 2011, the European Commission (EU) has approved steviol glycosides as a new food additive (E 960). The recent green light will probably lead to wide-scale use of Stevia-derived products [96]. S. rebaudiana may be used as an alternative of synthetic additives in marketed food products [97,98]. Stevia leaf extracts can be a useful tool in order to provide new food beverages with a high content in antioxidant compounds. In this line, some authors combined cocoa powder [99] and exotic fruit juices [100] with Stevia extracts (as sweetener), obtaining a significant increase in bioactive compounds, mainly total phenolics compounds, in comparison to other samples with traditional sweeteners.

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Milk Fat Globule Membrane Material

Thien Trung Le, … Koen Dewettinck, in Studies in Natural Products Chemistry, 2014

Health-Beneficial Properties of MFGM PLs

Unlike MFGM proteins, for which health effects have been determined mostly via in vitro experiments and in vivo experiments with animal models, several PL components have been used already as therapeutics due to their medicinal properties.

Fat globules from both bovine and goat milk were able to inhibit the adhesion of Salmonella enteritidis to HT-29 human adenocarcinoma cells in a cultured cell experiment [173]. Tellez et al. [174] found that MFGM had an inhibitory effect on the virulence (expression of Shiga toxin gene) of E. coli O157:H7. It is interesting to know from the works of this group that heat treatment of milk did not decrease the antibacterial effect of the isolated MFGM material [173,174]. Sweet buttermilk powder, a material containing high concentration of MFGM, and not skimmed milk powder (containing limited amount of MFGM) was found to protect rats against Listeria monocytogenes infection, probably by preventing adherence of this pathogen to the intestinal mucosa [175]. A clinical study pointed out that regular consumption of formula enriched with a concentrated milk fat membrane product by preschool children was safe, well tolerated, and was associated with a significant decrease in the number of short febrile episodes and leads to improved behavioral regulation [176].

Dietary SM was found to contribute to myelination of the central nervous system (CNS) in developing rats of which serine palmitoyltransferase, a rate-limiting enzyme for sphingolipid biosynthesis, is inhibited [177]. As well, in experiments on rats, sphingolipids were found to inhibit colon carcinogenesis [178,179]. This protective effect against colon carcinogenesis of dietary sphingolipids was confirmed by feeding weanling Fischer-344 rats with MFGM (a mixture) [180]. A possible mechanism of action is that exogenously supplied sphingolipids bypass a sphingolipid signaling defect that is important in cancer (e.g., a loss of cellular SM turnover to produce ceramide and sphingosine) [181]. The role of sphingolipids in relation to colon health has been reviewed recently [182].

Sphingolipids are also involved in the intestinal uptake of cholesterol. SM was found to dose dependently lower the intestinal absorption of cholesterol and fats in rats [183185]. Sphingolipids, therefore, lower plasma cholesterol and TGs and protect the liver from fat- and cholesterol-induced steatosis [186,187]. However, the decreasing effect on plasma concentrations of these components was not evident in humans who were fed with an SM-enriched buttermilk formulation [188]. However, the authors noted that the SM-supplemented food might counteract the trend toward increased blood lipid concentrations caused by increased energy intake, as seen that the control food and not the SM-supplemented food that caused an increase in plasma concentrations of TG, LDL (low-density lipoprotein), and HDL (high-density lipoprotein) cholesterol, and apolipoprotein B after 4 weeks [188]. Digestion products of sphingolipids were shown to have antibacterial activity to various food-borne pathogens and then they can protect against food-borne gastroenteritis [189,190]. Physiological functions and clinical implications of sphingolipids in (and of) the gut have recently been reviewed [191].

PS is mostly concentrated in organs with high metabolic activity, such as the brain, lungs, heart, liver, and skeletal muscle. PS is located mainly in the internal layer of the cell membrane and has a variety of unique regulatory and structural functions, such as modulation of the activity of receptors, ion channels, enzymes and signaling molecules and involvement in governing membrane fluidity [192,193]. PS has been proposed to function as an endogenous regulator of immune and (anti-)inflammatory responses [194197]. Clinical studies have shown that consumption of PS may reduce the risk of dementia and cognitive dysfunction (of the Alzheimer type) in the elderly [192,198200]. Soy-derived PS is a safe nutritional supplement for older persons if taken up to a dosage of 200mg three times daily [201]. Explanation about the pharmacological and clinical effects of PS on the CNS has been reviewed [192]. Recent findings opened an option to use PS alone or in combination with omega-3 in the management of attention-deficit hyperactivity disorder [202,203].

Several randomized, double-blind, placebo-controlled studies have demonstrated that PC and PS may improve sport performance and can be an effective supplement for combating exercise-induced stress and preventing the physiological deterioration that can accompany too much exercise [193,204,205]. Findings related to effects of PS supplementation on exercised humans as well as the mechanisms of action have been reviewed by Kingsley [206].

PC and SM are sources of choline, which is an essential nutrient for humans because, especially, it is involved in brain development [207]. PC is effective in tư vấn of recovery of the liver after toxic or chronic viral damage, as shown in a multicenter, randomized, double-blind, placebo-controlled trial [208]. PC is an important constituent of the gastrointestinal tract. Oral administration of PC may help to maintain the defensive hydrophobic barrier and then protect the gastrointestinal mucosa against the damage caused by anti-inflammation drugs and chemicals [209218] and preventing bile salt toxicity to gastrointestinal epithelia and membranes [212]. PC and LysoPC showed anti-inflammatory effects in ulcerative colitis, a chronic inflammatory disorder of the colon [219222]. With double-blind trial conditions, PC demonstrated potentially lifesaving benefits against pharmaceutical and death cap mushroom poisoning, alcoholic liver damage, and the hepatitis B virus [223]. PC is safe and well tolerated beyond several grams of daily intake, and is highly cost affordable for the manufacture into functional foods [224]. Pharmacological effects of PC along with its mechanisms of action, dosage, and side effects can be seen in the monograph of Kidd [223]. A monograph on PS is also available [225].

Gangliosides are sialic acid-containing glycosphingolipids. These components, although present only in trace amounts, are believed to be very important in the development of brain and gut immune system of infants. From the results obtained from feeding experiments in mice, Vazquez et al. [226], Clandinin et al. [227], and Park et al. [228] suggested that dietary gangliosides accelerate the maturation process of the intestinal immune system that takes place during weaning. Human milk gangliosides were found to be involved in the inhibition of E. coli and Vibrio cholerae enterotoxins [229,230]. Gangliosides were also found to prevent the adhesion of H. pylori to gastric epithelial cells [130,231,232]. All these results may indicate that human milk gangliosides may play an important role in protecting infants against enterotoxin-induced diarrhea. Cell surface gangliosides may function as unintended target receptors for bacterial adhesion in specific tissues [229,233]. The possible main mechanism by which these compounds can prevent the infection is that dietary gangliosides can act as putative decoys, due to its sialic acid groups, that interfere with pathogenic binding in the intestine [234]. Suh et al. [235] also found that feeding mice with gangliosides decreased the infection upon gastric incubation with Giardia muris (a parasite) compared with mice feeding with a control diet [235]. In vitro tests in this work also indicated direct toxicity of gangliosides to parasites [235]. In a clinical study where preterm infants were fed with a gangliosides-supplemented formula, Rueda et al. [236] found that gangliosides concentrations present in human milk significantly modified the fecal flora; increasing the Bifidobacteria content (prebiotic effect) and lowering the content of E. coli. Dietary gangliosides may promote intestinal immunity development in the neonate, and consequently in the prevention of infections during early infancy [234].

In mammals including humans, brain contains the highest relative ganglioside content in the body toàn thân toàn thân, particularly in neuronal cell membranes concentrated in the area of the synaptic membrane. The human brain contains two- to fourfold higher concentration of sialic acid than the brain of other mammals, including chimpanzees [237]. Gangliosides are known to be an essential nutrient for neuronal growth, migration and maturation, neuritogenesis, synaptogenesis, and myelination [238240]. Because the liver, where sialic acid can be synthesized from simple sugar precursors, of newborn infants is relatively immature and due to the rapid growth and development of the brain, dietary sources of sialic acid may play a role in determining the final concentration of sialic acid in the brain and may possibly influence the learning ability of human infants [241]. There has been evidence from animal studies that sialic acid supplementation is associated with increases of gangliosides in the brain and improved learning and memorial ability [242,243]. For learning more about potential uses of gangliosides as therapeutic intervention, readers are referred to some of the review papers [234,239,244]. Methods for determination of sialic acid and gangliosides in biological samples and dairy products have recently reviewed by Lacomba et al. [245]. Other health-relating effects of PLs are described in the review of Dewettinck et al. [48].

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