Aggregation Substance Research Articles

S. aureus develops biofilms on titanium within 2 weeks in vitro.

The formation of biofilms, characterized by cell aggregation and extracellular polymeric substance (EPS) production, is a common feature of periprosthetic joint infections (PJI). The current study aimed to investigate the development of biofilm features in vitro within less than 3 weeks by Staphylococcus aureus isolated from PJIs. Biofilms were grown on sandblasted titanium discs, and fluorescence spectroscopy and microscopy were used to observe biofilm maturation for 21 days. DNA mass decreased initially, then increased from day 5 onwards, and decreased again after day 7. The proportion of living to dead bacteria oscillated until day 7 and increased at day 10 for strain A and day 14 for strain B. EPS mass decreased initially and then continuously increased. Multilayer bacterial organization was observed at day 7. Cell aggregation occurred during the first week, followed by EPS production in the second week, and characteristic biofilm features were observed within 1 to 2 weeks.

Prevalence and virulence factors of haemolytic Enterococcus faecalis isolated from root filled teeth associated with periradicular lesions: A laboratory investigation in Thailand.

Previous endodontic research has provided limited understanding of the prevalence and roles of haemolytic and non-haemolytic Enterococcus faecalis strains in root filled teeth. This study aimed to determine the prevalence of these strains in root filled teeth with periradicular lesions and investigate their associated virulence factors. A total of 36 root canal samples were collected from 36 subjects. The prevalence of E. faecalis was determined using culture and PCR methods. Antibiotic susceptibility of haemolytic and non-haemolytic E. faecalis strains was assessed using the broth dilution assay. The cytokine stimulation in periodontal ligament (PDL) cells and neutrophil migration were evaluated using real-time PCR and migration assay, respectively. Cell invasion ability of the strains was assessed using a cell culture model. Additionally, the virulence gene expression of the haemolytic and non-haemolytic strains was investigated using real-time PCR. The Mann-Whitney U and Spearman's ρ tests were used to examine the significant difference between the two strains and to analyse the correlation between phenotype and gene expression, respectively. Enterococcus faecalis was detected in 33.3% and 88.9% of samples by culture and real-time PCR, respectively. Haemolytic strains were found in 36.4% of subjects. Non-haemolytic strains exhibited susceptibility to erythromycin and varying susceptibility to tetracycline, while all haemolytic strains were resistant to both antibiotics. Haemolytic strains significantly upregulated the expression of IL-8, OPG and RANKL in PDL cells (p < .05). Notably, the fold increases in these genes were higher: IL-8 (556.1 ± 82.9 vs. 249.6 ± 81.8), OPG (2.2 ± 0.5 vs. 1.3 ± 0.2) and RANKL (1.8 ± 0.3 vs. 1.2 ± 0.1). Furthermore, haemolytic strains had a greater effect on neutrophil migration (68.7 ± 15.2% vs. 46.9 ± 11.4%) and demonstrated a higher level of internalization into oral keratinocyte cells (68.6 ± 0.4% vs. 33.8 ± 0.5%) (p < .05). They also showed enhanced expression of virulence genes associated with haemolysin, surface proteins, collagen-binding and aggregation substances. Gelatinase activity was only detectable in non-haemolytic strains. This study revealed that haemolytic strains E. faecalis possessed enhanced abilities in host invasion and a higher abundance of virulence factors, suggesting their potential contribution to more severe disease manifestations.

Enterococcus Species: A Systemic Review

Enterococci are gram-positive facultative anaerobes, these are commensals in the intestinal system of numerous animals, including humans. They affect hospitalized patients and cause nosocomial infections, respiratory infections, endocarditis, wound infections, UTIs, and other enterococcal infections. This discovery can be explained by hemolysin, gelatinase, aggregation substances, hyaluronidase, capsular polysaccharides, and cell wall carbohydrate. Various enterococcal spp. include Enterococcus avium Vancomycin resistance was acquired by enterococci throughout the antibacterial spectrum, primary antibiotic used regimen based on dual β lactams and aminoglycosides.

Virulence genes and antimicrobial resistance in Enterococcus strains isolated from dogs and cats in Northeast China.

This study aimed to characterize the antimicrobial resistance and virulence of Enterococcus from dogs and cats in Northeast China and evaluate its zoonotic risk based on a total of 469 enterococci strains from 610 samples, including 238 strains of E. faecium and 128 strains of E. faecalis. The isolation rate from police dog samples was 93.79%, pet dog samples was 69.90% and pet cat samples was 76.67%. The differences in the prevalence of E. faecalis among different hosts were statistically significant (P<0.05). The assays showed that most of the virulence genes detected were existed in E. faecalis and police dogs carried the least number of virulence genes. The correlation between enterococcal surface protein (esp) and aggregation substance (asa1) was determined. Enterococci are most resistant to tetracycline and erythromycin, 68.92% of the isolates were classified as multiple drug resistant. Significant differences (P<0.01) were found between E. faecium and E. faecalis in the resistance rates of nine antimicrobials. Four positive and four negative correlations were found between virulence genes and antimicrobial resistance. The results show that Enterococcus colonization and excretion in dogs and cats were related to animal species and living environments. Some correlation between virulence factors and antimicrobial resistance was obtained. This study confirmed the presence of strains carrying multiple virulence factors and antimicrobial resistance at the same time, suggesting a public health risk for dogs and cats as reservoirs of enterococci.

Antimicrobial Resistance and Virulence Genes of Enterococci Isolated from Water Buffalo's Subclinical Mastitis

This study aimed to investigate the antimicrobial resistance and virulence genes of enterococci isolated from water buffalo’s subclinical mastitis cases. The antimicrobial susceptibilities of the isolates were determined by the disc diffusion method. Identification at the species level of enterococci, virulence [aggregation substance (asa1), gelatinase (gelE), cytolysin (cylA), enterococcal surface protein (esp), and hyaluronidase (hyl)] and resistance genes [macrolide (ermA, ermB, mefA/E) and tetracycline (tetK, tetL, tetM, tetO, and tetS)] were investigated by polymerase chain reaction (PCR). Overall, Enterococcus spp. was recovered from 65 of 200 (32.5%) mastitic milk samples, comprising E. faecium (n=26), E. durans (n=22), E. faecalis (n=12), and E. hirae (n=5). Most isolates (56.9%) were susceptible to all tested antibiotics. The rest of the isolates showed various rate of resistance against rifampicin (23.1%), tetracycline (21.5%), quinupristin-dalfopristin (10.8%), ciprofloxacin (7.7%), erythromycin (6.2%), and chloramphenicol (3.1%). Out of 65 enterococci, only 16 (24.6%) were detected to have virulence genes, of which 12 were positive for gelE, seven were positive for esp, two were positive for asa1, and one was positive for hlyA. The gene cylA was not detected in any isolate tested. Resistance to tetracycline was mainly associated with tetM. Two erythromycin-resistant isolates were positive for ermB, and one was positive for mefA/E. This study was the first to report species distribution, antimicrobial susceptibility, and virulence traits of enterococci isolated from subclinical mastitis of water buffaloes in Çorum Province, Türkiye.

Antibacterial and anti-biofilm activity of diarylureas against Enterococcus faecium by suppressing the gene expression of peptidoglycan hydrolases and adherence.

Enterococcus faecium (E. faecium) is a clinical multidrug-resistant pathogen causing life-threatening infection, which makes it important to discover antibacterial agents with novel scaffolds and unique mechanism. In this study, the diarylurea scaffold was found to have potent antibacterial effect on E. faecium. Diarylurea ZJ-2 with benign drug-like property exhibited potent antibacterial and anti-biofilm activity through inhibiting the genes expression of NlpC/p60 hydrolase-secreted antigen A (sagA) and autolysins (atlA), down-regulating the expression of biofilm adherence related genes aggregation substance (agg), enterococcal surface protein (esp) against E. faecium. Moreover, ZJ-2 can be docked into SagA to inhibit daughter cell separation. In a mouse model of abdominal infection, ZJ-2 decreased the bacterial load and the level of IL-6 and TNF-α in a time-dependent manner. Overall, these findings indicated that diarylurea ZJ-2 has the potential to be developed as a therapeutic agent to treat drug-resistant enterococci and biofilm-related infections.

Pheromone Activity after Stimulation with Ampicillin in a Plasmid-Free Enterococcus faecalis Strain.

Enterococci exhibit clumping under the selective pressure of antibiotics. The aim of this study was to analyze the effect of supernatants from a plasmid-free clone (C29) of Enterococcus faecalis subjected to 0.25×, 0.5×, and 0.75× of the minimal inhibitory concentration (MIC) of ampicillin on the expression of an aggregation substance (AS) by a donor plasmid clone (1390R). A clumping assay was performed. The relative expression of prgB (gene that encodes AS) was determined and semiquantified in 1390R, and iad1 expression was determined and semiquantified in C29. AS expression was analyzed in the stimulated 1390R cells by confocal microscopy, flow cytometry, and ELISA. Adherence was also measured. Maximal clumping was observed with the pheromone medium 0.25×. Only the 1390R strain stimulated with the C29 supernatant without ampicillin and with 0.25× was able to express prgB. No expression of prgB was observed at 0.5× and 0.75×. The difference in relative expression (RE) of 1390R without ampicillin and with 0.25× was 0.5-fold. AS expression in 1390R showed the greatest increase upon stimulation with 0.25×. When 1390R was stimulated with 0.5× and 0.75×, AS expression was also observed but was significantly lower. Ampicillin stimulated C29 switch-off pheromone expression in recipient cells, which in turn switched off AS expression in donor cells. We observed that although prgB was switched off after 0.5× stimulation in C29, the supernatants induced expression in certain 1390R strains. In conclusion, ampicillin was able to modulate pheromone expression in free plasmid clones which, in turn, modulated AS expression in plasmid donor cells. The fact that PrgB gene expression was switched off after the ampicillin stimulus at 0.5× MIC, whereas AS proteins were present on the surface of the bacteria, suggested that a mechanism of rescue associated with mechanism pheromone sensing may be involved.

Abetting host immune response by inhibiting rhipicephalus sanguineus Evasin-1: An in silico approach.

The brown dog tick (Rhipicephalus sanguineus) is the most prevalent tick in the world and a well-recognized vector of many pathogens affecting dogs and occasionally humans. Pathogens exploit tick salivary molecules for their survival and multiplication in the vector and transmission to and establishment in the hosts. Tick saliva contains various non-proteinaceous substances and secreted proteins that are differentially produced during feeding and comprise of inhibitors of blood congealing and platelet aggregation, vasodilatory and immunomodulatory substances, and compounds preventing itch and pain. One of these proteins is Evasin-1, which has a high binding affinity to certain types of chemokines. The binding of Evasin-1 to chemokines prevents the detection and immune response of the host to R. sanguineus, which may result in the successful transmission of pathogens. In this study, we screened potential Evasin-1 inhibitor based on the pharmacophore model derived from the binding site residues. Hit ligands were further screened via molecular docking and virtual ADMET prediction, which resulted in ZINC8856727 as the top ligand (binding affinity: -9.1 kcal/mol). Molecular dynamics simulation studies, coupled with MM-GBSA calculations and principal component analysis revealed that ZINC8856727 plays a vital role in the stability of Evasin-1. We recommend continuing the study by developing a formulation that serves as a potential medicine aid immune response during R. sanguineus infestation.

Safety Assessment of Fecal, Bacteriocin-Producing Strains Enterococcus mundtii from Horses

Backround: Knowing and optimizing the host microbiota is important regarding the maintenance of horse`s health. For this approach beneficial bacteria have been usually used. However, to be the most effective in use, their safety, tolerability and efficacy needs to be assessed. Therefore, fecal strains Enterococcus mundtii from horses with promising bacteriocinogenic potential have to be evaluated for their safety. Methodology: E. mundtii strains were isolated from feces of 47 horses (n=47; 40 mares and seven stallions), the Norik breed from Muráň in eastern Slovakia. MALDTI-TOF spectrometry and sequencing were used. Phenotypic characteristics were assessed in accordance with those for the reference strain E. mundtii ATCC43186. Biofilm-forming ability was tested using plate assay. For enzyme production commercial tests were applied and virulence factor genes were tested using PCR and primers. Antibiotic profile was tested with diffusion method. In vivo safety was tested using Balb/c breed mice. Results: E. mundtii strains did not produce the enzyme β-glucuronidase; however, most E. mundtii strains produced β-galactosidase. The strains were absent of virulence factors such as gelatinase, aggregation substance, cytolysin A, enterococcal superficial protein, adhesins, hyaluronidase and IS16 element, except efaAfs gene in the strain EMKD 24/1. Six strains were found with lowgrade (0.1 ≤ A570&lt; 1) biofilm - forming ability. E. mundtii were mostly susceptible to antibiotics. Bacteriocinogenic strain EMKD41/3 reached high counts in feces (5.12 ± 0.26 CFU/g log 10) of Balb/c mice during its 30 days application. No mortality of mice was noted during whole period of EMKD41/3 strain application. Conclusion: Bacteriocin-producing strains E. mundtii should not threaten horses because they were mostly susceptible to antibiotics, they were virulence factor genes absent and with low-grade biofilm formation ability. Bacteriocinproducing strain EMKD41/3 even indicates its sufficient implementation in host organism with any side effect.

Hidden agenda of Enterococcus faecalis lifestyle transition: planktonic to sessile state.

Enterococcus faecalis, a human gastrointestinal tract commensal, is known to cause nosocomial infections. Interestingly, the pathogen's host colonization and persistent infections are possibly linked to its lifestyle changes from planktonic to sessile state. Also, the multidrug resistance and survival fitness acquired in the sessile stage of E. faecalis has challenged treatment regimes. This situation exists because ofthe critical role played by several root genes and their molecular branches, which are part of quorum sensing, aggregation substance, surface adhesions, stress-related response and sex pheromones in the sessile state. It is therefore imperative to decode the hidden agenda of E. faecalis and understand the significant factors influencing biofilm formation. This would, in turn, augment the development of novel strategies to tackle E. faecalis infections.

Dynamics of plasmid-mediated niche invasion, immunity to invasion, and pheromone-inducible conjugation in the murine gastrointestinal tract

Microbial communities provide protection to their hosts by resisting pathogenic invasion. Microbial residents of a host often exclude subsequent colonizers, but this protection is not well understood. The Enterococcus faecalis plasmid pCF10, whose conjugative transfer functions are induced by a peptide pheromone, efficiently transfers in the intestinal tract of mice. Here we show that an invading donor strain established in the gastrointestinal tract of mice harboring resident recipients, resulting in a stable, mixed population comprised of approximately 10% donors and 90% recipients. We also show that the plasmid-encoded surface protein PrgB (Aggregation Substance), enhanced donor invasion of resident recipients, and resistance of resident donors to invasion by recipients. Imaging of the gastrointestinal mucosa of mice infected with differentially labeled recipients and donors revealed pheromone induction within microcolonies harboring both strains in close proximity, suggesting that adherent microcolonies on the mucosal surface of the intestine comprise an important niche for cell-cell signaling and plasmid transfer.

Safety Evaluation of Weissella cibaria JW15 by Phenotypic and Genotypic Property Analysis.

Weissella cibaria is one of the bacteria in charge of the initial fermentation of kimchi and has beneficial effects such as immune-modulating, antagonistic, and antioxidant activities. In our study, we aimed to estimate the safety of W. cibaria JW15 for the use of probiotics according to international standards based on phenotypic (antibiotic resistance, hemolysis, and toxic metabolite production) and genotypic analysis (virulence genes including antibiotic resistance genes). The results of the safety assessment on W. cibaria JW15 were as follows; (1) antibiotic resistance genes (ARGs) (kanamycin and vancomycin etc.) were intrinsic characteristics; (2) There were no acquired virulence genes including Cytolysin (cylA), aggregation substance (asa1), Hyaluronidase (hyl), and Gelatinase (gelE); (3) this strain also lacked β-hemolysis and the production of toxic metabolites (D-lactate and bile salt deconjugation). Consequently, W. cibaria JW15 is expected to be applied as a functional food ingredient in the food market.

VIRULENCE FACTORS, ANTIBIOTIC RESISTANCE, AND ANTIMICROBIAL ACTIVITY OF ENTEROCOCCUS SPP. ISOLATED FROM DIFFERENT SOURCES IN ALGERIA

This study aimed to isolate and identify different Enterococcus spp. from diverse sources including dromedary raw milk, rhizospheric soil and natural saline water samples and to determine their antimicrobial activities and safety aspects. From these sources, distinct strains of E. faecium, E. durans, E. hirae, and E. gallinarum species were detected. No virulence factors were observed for six Enterococcus strains while none of the tested Enterococci harboured the genes encoding cytolysin and aggregation substance. All tested strains showed a high sensitivity to many antibiotics, particularly vancomycin, and exhibited a remarkable antagonist activity toward Salmonella typhimurium, Fusarium graminearum and Penicillium expansum. PCR testing of enterocins revealed the co-presence of entA and entB among all tested Enterococci. No hemolytic reaction was also detected in Enterococci isolates, except for six strains. Based on these findings, potential candidates for use as biocontrol agents or probiotic starters were selected for further studies.

Activity of Selected Group of Monoterpenes in Alzheimer's Disease Symptoms in Experimental Model Studies-A Non-Systematic Review.

Alzheimer’s disease (AD) is the leading cause of dementia and cognitive function impairment. The multi-faced character of AD requires new drug solutions based on substances that incorporate a wide range of activities. Antioxidants, AChE/BChE inhibitors, BACE1, or anti-amyloid platelet aggregation substances are most desirable because they improve cognition with minimal side effects. Plant secondary metabolites, used in traditional medicine and pharmacy, are promising. Among these are the monoterpenes—low-molecular compounds with anti-inflammatory, antioxidant, enzyme inhibitory, analgesic, sedative, as well as other biological properties. The presented review focuses on the pathophysiology of AD and a selected group of anti-neurodegenerative monoterpenes and monoterpenoids for which possible mechanisms of action have been explained. The main body of the article focuses on monoterpenes that have shown improved memory and learning, anxiolytic and sleep-regulating effects as determined by in vitro and in silico tests—followed by validation in in vivo models.

Phenotype-Genotype Correlations and Distribution of Key Virulence Factors in Enterococcus faecalis Isolated from Patients with Urinary Tract Infections.

Background and ObjectiveEnterococcus faecalis can cause different nosocomial infections, especially urinary tract infection (UTI). Pathogenicity of E. faecalis is driven by various virulence factors; however, no specific genetic pattern is restricted to a particular type of infection. The current study aimed to investigate the correlation between different virulence factors in E. faecalis clinical isolates causing UTIs.MethodsWe phenotypically analyzed 60 urinary isolates, identified as E. faecalis, for biofilm formation, gelatinase, protease and hemolytic activities by Crystal Violet assay, gelatin hydrolysis, casein hydrolysis and blood agar hemolysis assays, respectively. Additionally, we detected different genes associated with species identification, virulence phenotypes, adherence and quorum sensing by the polymerase chain reaction (PCR). The detected genes included D-alanine-D-alanine ligase (ddl), cytolysin (cyl), gelatinase (gelE), serine protease (sprE), faecal streptococci regulator locus genes (fsrA, fsrB, fsrC), pili (pil), adhesin to collagen of E. faecalis (ace) and aggregation substance (agg).ResultsAll isolates formed biofilms, mostly with strong to moderate ability. Although gelE was detected in 87% of the isolates, only 22% of the isolates had gelatinase activity. Similar phenotype–genotype incongruities were observed with hemolysis and casein hydrolysis activities, as the isolates that expressed these two phenotypes were fewer than those carrying the genes encoding them.ConclusionA clear variability in virulence gene distribution among the isolates was observed, and no particular pattern was associated with UTI. Whereas all isolates carried at least ace and pil, whose products are involved in adherence, which is a virulence phenotype that is required for urinary colonization, six isolates carried the entire set of investigated genes. Statistical analysis of the results suggests cyl as a biomarker for hemolytic activity, fsrB as a diagnostic biomarker for the gelatinase activity, and gelE-sprE as predictors for biofilm formation strength in E. faecalis.

Enterococcal Species Associated with Slovak Raw Goat Milk, Their Safety and Susceptibility to Lantibiotics and Durancin ED26E/7

Goat milk has become a popular item of human consumption due to its originality. Enterococci are ubiquitous bacteria, and they can also be found in traditional dairy products. This study focuses on the safety of enterococci from Slovak raw goat milk and on their susceptibility to lantibiotic bacteriocins and durancin ED26E/7, which has not previously been studied. Biofilm formation ability in enterococci, virulence factor genes, enzyme production and antibiotic profile were investigated. Samples of raw goat milk (53) were collected from 283 goats in Slovakia. MALDI-TOF mass spectrometry identified three enterococcal species: Enterococcus faecium, E. hirae and E. mundtii, with dominant occurrence of the species E. faecium. Low-grade biofilm formation ability (0.1 ≤ A570 &lt; 1.0) was found in four strains of E. faecium. Gelatinase, hyaluronidase, aggregation substance and enterococcal surface protein genes were absent in these enterococci. Gene efaAfm (adhesin) was detected in five E. faecium strains. However, it was not detected in biofilm-forming strains. Enterococci detected in Slovak raw goat milk were found not to have pathogenic potential; four strains even produced high amounts of useful β-galactosidase. The strains were susceptible to lantibiotic bacteriocin treatment and to durancin ED26E/7 as well, which represents original information in dairy production.

Pathogenic potential of Enterococcus faecalis strains isolated from root canals after unsuccessful endodontic treatment.

To evaluate strains of Enterococcus faecalis isolated from endodontic failures cases for (a) presence of virulence genes, namely, gelatinase production (gelE), surface protein (esp), collagen-binding adhesin (ace), cytolysin activator (cylA), E. faecalis antigen A (efaA) and aggregation substance (asa), all by using PCR; (b) biofilm formation capacity; and (c) activity of gelatinase and β-lactamase. Twenty-five strains of E. faecalis were tested. The DNA extracted from these strains was used for identification of virulence genes by PCR and 1% agarose gel. Biofilm formation was performed on polystyrene microplates by using the violet crystal staining method. For assessment of the gelatinase activity, inoculum of pure cultures was deposited in tubes containing gelatin and a nutrient broth, whereas nitrocefin disks were used to assess the β-lactamase action. The virulence genes efaA and cylA were detected in 100% of the strains, whereas gelE was present in 84%, ace in 68%, esp in 56% and asa in 48%. Four strains had no biofilm formation, 17 had poor formation and four had moderate formation. Gelatinase production was observed in three strains and β-lactamase resistance in five strains of E. faecalis. Diverse patterns of virulence gene detection were observed among the E. faecalis strains, with predominance of those capable of forming biofilm. A few strains have been found to hydrolyze gelatin proteins, whereas β-lactamase resistance was detected in different isolates. To understand the influence of virulence factors in E. faecalis on the host heath status.

In vitro assessment of probiotic and virulence potential of Enterococcus faecium strains derived from artisanal goatskin casing Tulum cheeses produced in central Taurus Mountains of Turkey

In the present study, nine Enterococcus (Ent.) faecium isolates were isolated from Tulum cheese produced traditionally in the central Taurus Mountains of Turkey during ripening period and were characterized to investigate their probiotic potential via gastrointestinal resistance, and adhesion ability, functional properties tests, and safety (haemolytic activity, antibiotic resistance, biogenic amine production, and PCR detection of some virulence factors) analyses. All of these strains proved to be resistant to bile salt and simulated gastric juice. All the isolates displayed good safety assessment regarding vancomycin susceptibility except for isolate 1050. Additionally, the majority of isolates showed high exopolysaccharide production while isolate 12 showed a desirable cholesterol removal rate. Also, five of Ent. faecium isolates indicated antibacterial activity against both Listeria monocytogenes ATCC 7644 and Staphylococcus aureus ATCC 25923. Isolates 394 and 894 were examined based on the presence of virulence genes encoding for aggregation substance (asa1), cytolysin (CylLL, CylLs, CylM, CylB, CylA), gelatinase (gelE), and hyaluronidase (hylefm). Isolate 894 harbored three virulence determinants including asa1, gelE and CylA while the virulence cylLL,S,cylM, Hylefm, gelE, and CylA genes were detected in isolate 394. Overall, isolate 894 was shown to be a potential candidate for further in vivo investigations as a probiotic culture.

Effect of Prostanoids on Human Platelet Function: An Overview.

Prostanoids are bioactive lipid mediators and take part in many physiological and pathophysiological processes in practically every organ, tissue and cell, including the vascular, renal, gastrointestinal and reproductive systems. In this review, we focus on their influence on platelets, which are key elements in thrombosis and hemostasis. The function of platelets is influenced by mediators in the blood and the vascular wall. Activated platelets aggregate and release bioactive substances, thereby activating further neighbored platelets, which finally can lead to the formation of thrombi. Prostanoids regulate the function of blood platelets by both activating or inhibiting and so are involved in hemostasis. Each prostanoid has a unique activity profile and, thus, a specific profile of action. This article reviews the effects of the following prostanoids: prostaglandin-D2 (PGD2), prostaglandin-E1, -E2 and E3 (PGE1, PGE2, PGE3), prostaglandin F2α (PGF2α), prostacyclin (PGI2) and thromboxane-A2 (TXA2) on platelet activation and aggregation via their respective receptors.

Safety evaluation and bacteriocinogenic potential of Pediococcus acidilactici strains isolated from artisanal cheeses

Pediococcus acidilactici ST1607V, ST2104V and ST3105V, isolated from a Brazilian artisanal cheese expressed bacteriocins with high inhibitory activity against several strains of Listeria monocytogenes and Enterococcus spp., but not against most of the other tested lactic acid bacteria (LAB). Bacteriocinogenic activity against L. monocytogenes ATCC7644 was expressed with a high titre of 51200 AU/mL (ST1607V and ST2104V) and 25600 AU/mL (ST3105V), when cultured in MRS. Bacteriocins produced by strains ST1607V, ST2104V and ST3105V presented a bactericidal mode of action against L. monocytogenes ATCC7644 and Enterococcus faecium ATCC19434. DNA of the studied LAB strains was obtained and subjected to PCR assays targeting more than 50 genes related to biogenic amines production (histidine, tyrosine and ornithine decarboxylases), virulence (sex pheromones, gelatinase, cytolysin, hyaluronidase, aggregation substance, enterococcal surface protein, endocarditis antigen, adhesion of collagen, integration factors) and antibiotic resistance (vancomycin, tetracycline, erythromycin, gentamicin, chloramphenicol, bacitracin). A few safety-related genes were detected in some strains, indicating their safety for application in fermented food products. Special attention should be given to the presence of possible virulence factors, in addition to the production of biogenic amines and antibiotic resistance. Additional in vitro and in vivo experiments could be designed for future evaluation of possible expression of detected virulence genes.