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1.
Heliyon ; 9(12): e22979, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38125458

ABSTRACT

The European research area exhibits considerable opacity and fragmentation in food safety research funding and organizational structures, impeding the exploitation of existing research potential across European countries. Given that food safety is inherently linked to the societal challenges of our time, identifying and removing existing barriers to research funding in this area is crucial. Towards investigating this matter, interviews were conducted with funding bodies from six European countries to assess key issues related to research funding in general and food safety in particular. Funding experts were then invited to a workshop to jointly discuss the challenges identified and explore strategies to address them. Evaluation of the food safety research funding situation in selected European countries revealed both convergences and significant differences among national funding bodies. Engaging with funding experts provided invaluable insights into the issues encountered with research funding, such as inadequate call management staff or insufficient research funds, culminating in a set of recommendations for action to remedy the situation.

2.
Front Cell Infect Microbiol ; 13: 1176755, 2023.
Article in English | MEDLINE | ID: mdl-37424779

ABSTRACT

Introduction: Surgical site infection remains a devastating and feared complication of surgery caused mainly by Staphylococcus aureus (S. aureus). More specifically, methicillin-resistant S. aureus (MRSA) infection poses a serious threat to global health. Therefore, developing new antibacterial agents to address drug resistance are urgently needed. Compounds derived from natural berries have shown a strong antimicrobial potential. Methods: This study aimed to evaluate the effect of various extracts from two arctic berries, cloudberry (Rubus chamaemorus) and raspberry (Rubus idaeus), on the development of an MRSA biofilm and as treatment on a mature MRSA biofilm. Furthermore, we evaluated the ability of two cloudberry seed-coat fractions, hydrothermal extract and ethanol extract, and the wet-milled hydrothermal extract of a raspberry press cake to inhibit and treat biofilm development in a wound-like medium. To do so, we used a model strain and two clinical strains isolated from infected patients. Results: All berry extracts prevented biofilm development of the three MRSA strains, except the raspberry press cake hydrothermal extract, which produced a diminished anti-staphylococcal effect. Discussion: The studied arctic berry extracts can be used as a treatment for a mature MRSA biofilm, however some limitations in their use exist.


Subject(s)
Methicillin-Resistant Staphylococcus aureus , Staphylococcal Infections , Humans , Staphylococcus aureus , Fruit , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Staphylococcal Infections/microbiology , Plant Extracts/pharmacology , Plant Extracts/therapeutic use , Biofilms , Growth and Development , Microbial Sensitivity Tests
3.
J Funct Biomater ; 14(4)2023 Mar 27.
Article in English | MEDLINE | ID: mdl-37103276

ABSTRACT

The goal of this study was to develop a sustainable, tannin-based option for silver-based and other current antimicrobial solutions for hospital privacy curtains. Commercial tree-derived tannins were characterized and their in vitro antibacterial properties against Staphylococcus aureus and Escherichia coli were determined. Hydrolysable tannins showed greater antibacterial efficacy than condensed tannins but differences in antibacterial efficacy between any of the tannins could not be attributed to their functional group content or molar mass. Outer membrane disruption was not a significant factor in antibacterial efficacy of tannins against E. coli. In a hospital field study, draw patches coated with hydrolysable tannins and affixed to privacy curtains reduced total bacteria count by 60% over eight weeks compared to their matching uncoated reference sides. In a follow-up laboratory study with S. aureus, very light spraying with water improved contact between bacteria and coating, enhancing the antibacterial effect by several orders of magnitude.

4.
Foods ; 11(4)2022 Feb 09.
Article in English | MEDLINE | ID: mdl-35205969

ABSTRACT

There is growing interest in Baltic herring (Clupea harengus membras) and other undervalued, small-sized fish species for human consumption. Gutting or filleting of small-sized fish is impractical; hence, the aim of this study was to explore the suitability of the whole (ungutted) herring for food use. The microbiological quality of commercially fished whole and gutted herring was analysed with culture-dependent methods combined with identification of bacterial isolates with MALDI-TOF Mass Spectrometry and culture-independent 16S rRNA gene amplicon sequencing. Whole and gutted herring had between 2.8 and 5.3 log10 CFU g-1 aerobic mesophilic and psychrotrophic bacteria and between 2.2 and 5.6 log10 CFU g-1 H2S-producing bacteria. Enterobacteria counts remained low in all the analysed herring batches. The herring microbiota largely comprised the phyla Proteobacteria, Firmicutes, and Actinobacteria (71.7% to 95.0%). Shewanella, Pseudomonas, and Aeromonas were the most frequently isolated genera among the viable population; however, with the culture-independent approach, Shewanella followed by Psychrobacter were the most abundant genera. In some samples, a high relative abundance of the phylum Epsilonbacteraeota, represented by the genus Arcobacter, was detected. This study reports the bacterial diversity present in Baltic herring and shows that the microbiological quality was acceptable in all the analysed fish batches.

5.
Food Chem ; 373(Pt B): 131524, 2022 Mar 30.
Article in English | MEDLINE | ID: mdl-34782215

ABSTRACT

This study aimed to establish the differences between enzymatically extracted hydrolysates and pH shifted protein isolates from whole Baltic herring and roach in terms of polypeptide patterns, functionality, sensory properties, microbial quality, yield, and composition. Alkaline extraction resulted in the highest yields, whereas the hydrolysates showed the highest protein contents. The hydrolysates showed higher protein solubility (86.0-88.5%) than the protein isolates (5.1-14.5%) as well as the higher foam capacity for Baltic herring. However, for roach, alkaline extracted protein isolates exhibited the highest foam capacity. All hydrolysates showed poor foam stability (0-13%) while the protein isolates showed notably higher stability (30-55%). The hydrolysates showed relatively low bitterness, whereas alkaline extracted roach proteins were perceived as bitter. This study demonstrated that it was possible to produce protein isolates and hydrolysates from whole fish with good microbial quality. However, both processes need to be optimised according to the food application and fish species.


Subject(s)
Cyprinidae , Fishes , Animals , Hydrogen-Ion Concentration
6.
Antibiotics (Basel) ; 10(12)2021 Dec 03.
Article in English | MEDLINE | ID: mdl-34943693

ABSTRACT

Staphylococcus aureus is the most common cause of surgical site infections and its treatment is challenging due to the emergence of multi-drug resistant strains such as methicillin-resistant S. aureus (MRSA). Natural berry-derived compounds have shown antimicrobial potential, e.g., ellagitannins such as sanguiin H-6 and lambertianin C, the main phenolic compounds in Rubus seeds, have shown antimicrobial activity. The aim of this study was to evaluate the effect of sanguiin H-6 and lambertianin C fractionated from cloudberry seeds, on the MRSA growth, and as treatment of a MRSA biofilm development in different growth media in vitro and in vivo by using a murine wound infection model where sanguiin H-6 and lambertianin C were used to prevent the MRSA infection. Sanguiin H-6 and lambertianin C inhibited the in vitro biofilm development and growth of MRSA. Furthermore, sanguiin H-6 showed significant anti-MRSA effect in the in vivo wound model. Our study shows the possible use of sanguiin H-6 as a preventive measure in surgical sites to avoid postoperative infections, whilst lambertianin C showed no anti-MRSA activity.

7.
Foods ; 9(11)2020 Oct 26.
Article in English | MEDLINE | ID: mdl-33114534

ABSTRACT

Interest in using undervalued forage fish for human consumption has recently increased due to its environmental benefits. However, feasible strategies to process the undervalued fish species to food use are limited. Therefore, this study investigated the possibility to utilise whole (ungutted) Baltic herring as a raw material for hybrid plant-fish meat analogues produced by high-moisture extrusion cooking. The sample properties were compared with ungutted Baltic herring. Produced meat analogues showed sufficiently high microbial quality, with spoilage microbes showing growth levels of under 1.4 log CFU/g. Whole fish and gutted fish extrudates showed uniform flavour- and odour-related sensory profiles. Colour values of the whole fish (L* 57.8) extrudates were similar to the values of gutted fish extrudates (L* 62.0). The whole and gutted fish extrudates had tensile strength in a cross-cut direction of 25.5 and 46.3 kPa, respectively. This correlated with the tearing force of the extrudates analysed by a trained sensory panel. Furthermore, a more explicit protein network was microscopically observed in gutted fish than in whole fish extrudates. The present study showed that high-moisture extrusion cooking enables the use of whole small-sized fish for human consumption.

8.
Food Res Int ; 113: 115-130, 2018 11.
Article in English | MEDLINE | ID: mdl-30195504

ABSTRACT

In order to assist developing a natural, safe food-preservative, aqueous ethanolic extracts of leaves and berries of eight Finnish berry plants were fractionated with Sephadex LH-20 column chromatography. For each fraction, phenolic compounds were analyzed with NMR, UPLC-DAD-ESI-MS and HPLC-DAD. The antioxidant activities of the fractions were investigated using oxygen radical absorbance capacity (ORAC) assay, and the antibacterial activities were evaluated against foodborne pathogens Staphylococcus aureus and Escherichia coli. Antioxidant activities of the fractions correlated highly with both the total concentration and structural feature of phenolic compounds, including both flavonoids and non-flavonoid phenolics. ORAC value correlated strongly with the concentration of (+)-catechin, (-)-epicatecin, quercetin glycosides, and anthocyanins. Increase in size and number of sugar moieties may reduce the antioxidative activities of quercetin glycosides. Type of sugar moieties may have a significant role in influencing peroxyl-radicals scavenging ability of quercetin glycosides with monosaccharides as a single sugar moieties. Most of the fractions inhibited the target microbes. S. aureus strains expressed a higher sensitivity to phenolic compounds than E. coli strains.


Subject(s)
Chemical Fractionation/methods , Dextrans , Fruit/chemistry , Phenols/isolation & purification , Plant Extracts/chemistry , Plant Leaves/chemistry , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Antioxidants/isolation & purification , Antioxidants/pharmacology , Chromatography/methods , Chromatography, High Pressure Liquid , Escherichia coli/drug effects , Finland , Indicators and Reagents , Magnetic Resonance Spectroscopy , Phenols/pharmacology , Rosaceae/chemistry , Rosales/chemistry , Spectrometry, Mass, Electrospray Ionization , Staphylococcus aureus/drug effects , Vaccinium vitis-idaea/chemistry
9.
Food Res Int ; 106: 291-303, 2018 04.
Article in English | MEDLINE | ID: mdl-29579930

ABSTRACT

Phenolic compounds were extracted with food grade solvent of acidified aqueous ethanol from leaves, berries, berry press cakes, and branches of Finnish berry plants and analyzed with HPLC-DAD, UPLC-DAD-ESI-MS and NMR. In addition, press cakes from two berry species and branches from one species were also extracted and analyzed with the same methods. The antioxidant activities of the extracts were evaluated using Folin-Ciocalteau, oxygen radical absorbance capacity (ORAC), DPPH free radical scavenging, and total radical trapping antioxidant parameter (TRAP) assays. The antibacterial activities were investigated against various Gram-negative and Gram-positive foodborne pathogens. The leaf extracts showed higher antioxidative activities (3-20 fold in ORAC assay, 10-20 fold in TRAP) than the berry extracts, in association with the higher contents of phenolic compounds in the leaf extracts; Strongest anti-bacterial effects was observed in the leaf extracts of lingonberry (Vaccinium vitis-idaea), sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) and saskatoon (Amelanchier alnifolia) on Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. However, the antibacterial efficacy varied with bacterial species and strains. The Folin-Ciocalteu, ORAC, and TRAP values was strongly correlated with the total content of flavonoids with less association shown with the content of total phenolics and flavonol glycosides. The results suggest a major contribution of pranthocyanidins and flavan-3-ols to the antioxidative activities of the extracts. The growth inhibition on Staphylococcus aureus and Bacillus cereus was clearly associated with the content of total phenolics and ellagitannins.


Subject(s)
Anti-Bacterial Agents/pharmacology , Antioxidants/pharmacology , Hippophae/chemistry , Plant Extracts/pharmacology , Rosaceae/chemistry , Vaccinium vitis-idaea/chemistry , Anti-Bacterial Agents/analysis , Antioxidants/analysis , Bacillus cereus/drug effects , Ethanol , Flavonoids/analysis , Flavonoids/pharmacology , Food Microbiology , Fruit/chemistry , Phenols/analysis , Plant Extracts/chemistry , Plant Leaves/chemistry , Plant Stems/chemistry , Proanthocyanidins/analysis , Proanthocyanidins/pharmacology , Staphylococcus aureus/drug effects
10.
Int J Food Microbiol ; 164(1): 99-107, 2013 Jun 03.
Article in English | MEDLINE | ID: mdl-23624538

ABSTRACT

The antimicrobial effects of the wood-associated polyphenolic compounds pinosylvin, pinosylvin monomethyl ether, astringin, piceatannol, isorhapontin, isorhapontigenin, cycloXMe, dHIMP, ArX, and ArXOH were assessed against both Gram-negative (Salmonella) and Gram-positive bacteria (Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus) and yeasts (Candida tropicalis, Saccharomyces cerevisiae). Particularly the stilbenes pinosylvin, its monomethyl ether and piceatannol demonstrated a clear antimicrobial activity, which in the case of pinosylvin was present also in food matrices like sauerkraut, gravlax and berry jam, but not in milk. The destabilization of the outer membrane of Gram-negative microorganisms, as well as interactions with the cell membrane, as indicated by the NPN uptake and LIVE/DEAD viability staining experiments, can be one of the specific mechanisms behind the antibacterial action. L. monocytogenes was particularly sensitive to pinosylvin, and this effect was also seen in L. monocytogenes internalized in intestinal Caco2 cells at non-cytotoxic pinosylvin concentrations. In general, the antimicrobial effects of pinosylvin were even more prominent than those of a related stilbene, resveratrol, well known for its various bioactivities. According to our results, pinosylvin could have potential as a natural disinfectant or biocide in some targeted applications.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Food Microbiology , Polyphenols/pharmacology , Stilbenes/pharmacology , Wood/chemistry , Caco-2 Cells , Cell Membrane/drug effects , Humans , Plant Extracts/pharmacology
11.
Syst Appl Microbiol ; 30(6): 494-508, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17583461

ABSTRACT

Twenty samples were taken from the inner or outer surfaces of stone monuments of six historic Scottish buildings and ruins. Biofilms developing on mineral substrates were analysed by in situ scanning electron microscopy and cultivation. Various methods were used to characterize the isolates including automated ribotyping, RAPD and sequencing of the 16S rRNA gene for bacteria, and stereomicroscopy and sequencing of the Internal Transcribed Spacers (ITS) for fungi. Most samples contained microbes between 10(5) and 10(7)cfug(-1) substrate. Actinobacteria belonging to the genus Streptomyces (17 samples/5 monuments) or Arthrobacter (12/3) and Pseudomonas (9/3) were frequently detected. Most streptomycetes were in terms of their 16S rRNA gene sequence most closely related to S. microflavus (10/3) or to the undescribed species S. "vulgaris" (8/3). Indoor and outdoor biofilms exhibited significant differences in their microbiota, as shown by both microscopy and isolation studies. Pigmented coccoid Arthrobacter species were typical for the outdoor samples, whereas Pseudomonas species were common in the indoor samples. Based on the low phylogenetic relationship to a known species (type strain), potential novel pigmented bacterial species belonging to the genera Arthrobacter, Brevundimonas, Cryseobacterium, Deinococcus and Dyadobacter were detected from the outdoor samples and to Pseudomonas from the indoor samples. Hyaline fungal species of Acremonium (10/4) mainly occurred in indoor samples, whereas pigmented species of Cladosporium (8/3), Penicillium (6/3) and Phialophora (6/2) were found outdoors. Using in situ microscopy diatom algae were also detected.


Subject(s)
Architecture , Bacteria, Aerobic/isolation & purification , Environmental Microbiology , Fungi/isolation & purification , Bacteria, Aerobic/classification , Bacteria, Aerobic/ultrastructure , Biofilms/growth & development , Fungi/classification , Fungi/ultrastructure , Molecular Sequence Data , RNA, Ribosomal, 16S/analysis , RNA, Ribosomal, 16S/genetics , Scotland
12.
J Agric Food Chem ; 55(10): 3905-12, 2007 May 16.
Article in English | MEDLINE | ID: mdl-17439151

ABSTRACT

Gram-negative bacteria are important food spoilage and pathogenic bacteria. Their unique outer membrane (OM) provides them with a hydrophilic surface structure, which makes them inherently resistant to many antimicrobial agents, thus hindering their control. However, with permeabilizers, compounds that disintegrate and weaken the OM, Gram-negative cells can be sensitized to several external agents. Although antimicrobial activity of plant-derived phenolic compounds has been widely reported, their mechanisms of action have not yet been well demonstrated. The aim of our study was to elucidate the role of selected colonic microbial metabolites of berry-derived phenolic compounds in the weakening of the Gram-negative OM. The effect of the agents on the OM permeability of Salmonella was studied utilizing a fluorescence probe uptake assay, sensitization to hydrophobic antibiotics, and lipopolysaccharide (LPS) release. Our results show that 3,4-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 3-(3,4-dihydroxyphenyl)propionic acid (3,4-diHPP), 3-(4-hydroxyphenyl)propionic acid, 3-phenylpropionic acid, and 3-(3-hydroxyphenyl)propionic acid efficiently destabilized the OM of Salmonella enterica subsp. enterica serovar Typhimurium and S. enterica subsp. enterica serovar Infantis as indicated by an increase in the uptake of the fluorescent probe 1-N-phenylnaphthylamine (NPN). The OM-destabilizing activity of the compounds was partially abolished by MgCl2 addition, indicating that part of their activity is based on removal of OM-stabilizing divalent cations. Furthermore, 3,4-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, and 3,4-diHPP increased the susceptibility of S. enterica subsp. enterica serovar Typhimurium strains for novobiocin. In addition, organic acids present in berries, such as malic acid, sorbic acid, and benzoic acid, were shown to be efficient permeabilizers of Salmonella as shown by an increase in the NPN uptake assay and by LPS release.


Subject(s)
Fruit/chemistry , Phenols/metabolism , Phenols/pharmacokinetics , Salmonella enterica/drug effects , 1-Naphthylamine/analogs & derivatives , 1-Naphthylamine/metabolism , Bacteriolysis/drug effects , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Membrane Permeability/drug effects , Fluorescent Dyes/metabolism , Lipopolysaccharides/metabolism , Salmonella enterica/metabolism , Salmonella enterica/ultrastructure
13.
Nutr Cancer ; 54(1): 18-32, 2006.
Article in English | MEDLINE | ID: mdl-16800770

ABSTRACT

Antimicrobial activity and mechanisms of phenolic extracts of 12 Nordic berries were studied against selected human pathogenic microbes. The most sensitive bacteria on berry phenolics were Helicobacter pylori and Bacillus cereus. Campylobacter jejuni and Candida albicans were inhibited only with phenolic extracts of cloudberry, raspberry, and strawberry, which all were rich in ellagitannins. Cloudberry extract gave strong microbicidic effects on the basis of plate count with all studied strains. However, fluorescence staining of liquid cultures of virulent Salmonella showed viable cells not detectable by plate count adhering to cloudberry extract, whereas Staphylococcus aureus cells adhered to berry extracts were dead on the basis of their fluorescence and plate count. Phenolic extracts of cloudberry and raspberry disintegrated the outer membrane of examined Salmonella strains as indicated by 1-N-phenylnaphthylamine (NPN) uptake increase and analysis of liberation of [14C]galactose- lipopolysaccharide. Gallic acid effectively permeabilized the tested Salmonella strains, and significant increase in the NPN uptake was recorded. The stability of berry phenolics and their antimicrobial activity in berries stored frozen for a year were examined using Escherichia coli and nonvirulent Salmonella enterica sv. Typhimurium. The amount of phenolic compounds decreased in all berries, but their antimicrobial activity was not influenced accordingly. Cloudberry, in particular, showed constantly strong antimicrobial activity during the storage.


Subject(s)
Anti-Infective Agents/pharmacology , Fruit/chemistry , Phenols/pharmacology , Plant Extracts/chemistry , 1-Naphthylamine/analogs & derivatives , 1-Naphthylamine/metabolism , Anthocyanins/pharmacology , Bacillus cereus/drug effects , Campylobacter jejuni/drug effects , Candida albicans/drug effects , Coumaric Acids/pharmacology , Escherichia coli/drug effects , Flavonols/pharmacology , Fragaria/chemistry , Helicobacter pylori/drug effects , Hippophae , Hydrolyzable Tannins/pharmacology , Lipopolysaccharides/metabolism , Phytotherapy , Ribes , Rosaceae/chemistry , Salmonella/drug effects , Staphylococcus aureus/drug effects , Vaccinium macrocarpon/chemistry , Vaccinium myrtillus/chemistry , Vaccinium vitis-idaea/chemistry
14.
Biofactors ; 23(4): 243-51, 2005.
Article in English | MEDLINE | ID: mdl-16498212

ABSTRACT

Phenolic compounds present in berries selectively inhibit the growth of human gastrointestinal pathogens. Especially cranberry, cloudberry, raspberry, strawberry and bilberry possess clear antimicrobial effects against e.g. salmonella and staphylococcus. Complex phenolic polymers, such as ellagitannins, are strong antibacterial agents present in cloudberry, raspberry and strawberry. Berry phenolics seem to affect the growth of different bacterial species with different mechanisms. Adherence of bacteria to epithelial surfaces is a prerequisite for colonization and infection of many pathogens. Antimicrobial activity of berries may also be related to anti-adherence activity of the berries. Utilization of enzymes in berry processing increases the amount of phenolics and antimicrobial activity of the berry products. Antimicrobial berry compounds are likely to have many important applications in the future as natural antimicrobial agents for food industry as well as for medicine.


Subject(s)
Anti-Infective Agents/pharmacology , Fruit/chemistry , Intestines/microbiology , Phenols/pharmacology , Cell Membrane/drug effects , Flavonoids/pharmacology , Food Handling , Humans , Lignans/pharmacology , Plant Extracts/pharmacology , Salmonella/drug effects , Staphylococcus/drug effects , Stilbenes/pharmacology , Tannins/pharmacology
15.
Appl Microbiol Biotechnol ; 67(1): 8-18, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15578177

ABSTRACT

Berry fruits are rich sources of bioactive compounds, such as phenolics and organic acids, which have antimicrobial activities against human pathogens. Among different berries and berry phenolics, cranberry, cloudberry, raspberry, strawberry and bilberry especially possess clear antimicrobial effects against, e.g. Salmonella and Staphylococcus. Complex phenolic polymers, like ellagitannins, are strong antibacterial agents present in cloudberry and raspberry. Several mechanisms of action in the growth inhibition of bacteria are involved, such as destabilisation of cytoplasmic membrane, permeabilisation of plasma membrane, inhibition of extracellular microbial enzymes, direct actions on microbial metabolism and deprivation of the substrates required for microbial growth. Antimicrobial activity of berries may also be related to antiadherence of bacteria to epithelial cells, which is a prerequisite for colonisation and infection of many pathogens. Antimicrobial berry compounds may have important applications in the future as natural antimicrobial agents for food industry as well as for medicine. Some of the novel approaches are discussed.


Subject(s)
Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Fruit/chemistry , Plant Extracts/pharmacology , Salmonella/drug effects , Staphylococcus/drug effects , Anti-Bacterial Agents/chemistry , Plant Extracts/chemistry , Plant Extracts/isolation & purification
16.
Microbiology (Reading) ; 143 ( Pt 10): 3193-3199, 1997 Oct.
Article in English | MEDLINE | ID: mdl-9353921

ABSTRACT

The effect of the polycation polyethyleneimine (PEI) on the permeability properties of the Gram-negative bacterial outer membrane was investigated using Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium as target organisms. At concentrations of less than 20 micrograms ml-1, PEI increased the bacterial uptake of 1-N-phenylnaphthylamine, which is a hydrophobic probe whose quantum yield is greatly increased in a lipid environment, indicating increased hydrophobic permeation of the outer membrane by PEI. The effect of PEI was comparable to that brought about by the well-known permeabilizer EDTA. Permeabilization by PEI was retarded but not completely inhibited by millimolar concentrations of MgCl2. PEI also increased the susceptibility of the test species to the hydrophobic antibiotics clindamycin, erythromycin, fucidin, novobiocin and rifampicin, without being directly bactericidal. PEI sensitized the bacteria to the lytic action of the detergent SDS in assays where the bacteria were pretreated with PEI. In assays where PEI and SDS were simultaneously present, no sensitization was observed, indicating that PEI and SDS were inactivating each other. In addition, a sensitizing effect to the nonionic detergent Triton X-100 was observed for P. aeruginosa. In conclusion, PEI was shown to be a potent permeabilizer of the outer membrane of Gram-negative bacteria.


Subject(s)
Gram-Negative Bacteria/drug effects , Polyethyleneimine/pharmacology , 1-Naphthylamine/analogs & derivatives , 1-Naphthylamine/pharmacokinetics , Cell Membrane Permeability/drug effects , Detergents/pharmacology , Drug Resistance, Microbial , Edetic Acid/pharmacology , Escherichia coli/drug effects , Escherichia coli/metabolism , Fluorescent Dyes/pharmacokinetics , Gram-Negative Bacteria/metabolism , Lipopolysaccharides/metabolism , Muramidase/pharmacology , Octoxynol/pharmacology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/metabolism , Salmonella typhimurium/drug effects , Salmonella typhimurium/metabolism
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