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Due to the alarming spread of resistance to classic antimicrobial agents, innovative therapeutic methods to combat antibiotic-resistant bacterial pathogens are urgently required. This minireview examines the enhancement of antibiotic efficacy by their combination with new antimicrobials, such as plant-derived compounds, metal ions and nanoparticles and bacteriophage lytic enzymes. The mechanisms of the observed synergy are also described. The promising results of basic research indicate that in future, combined therapy may be applied in human and veterinary medicine, agriculture and the food industry to combat bacterial pathogens.
The study has provided data on two Lactobacillus salivarius strains of poultry origin. The strains were investigated for the presence of genes encoding a bacteriocin: salivaricin B, and their localisation in chromosome or plasmid DNA. Specific primers were used to amplify a 224 bp fragment of salivaricin B gene (salB). RFLP analysis of PCR products revealed two DNA fragments of the predicted sizes upon digestion with Ndel and Xapl. Analysis with SspI allowed obtaining variability in two fragments in comparison to computer analysis of both strains, suggesting their divergency. It may be assumed that the amplified DNA fragments of salB gene share great, but not complete similarity to the previously described sequence of salB gene. Two examined strains showed different plasmid profiles; however bands of similar sizes were seen in both profiles. Genes responsible for salivaricin production are located on chromosomal DNA. Properties of these strains, in particular the presence of genes encoding bacteriocin production, imply that they may be used as potential probiotics for poultry.
Success in creating a synbiotic depends on compatibility between the chosen components – prebiotic and probiotic. In this work the interactions between Lactobacillus sp. strains isolated from yogurts and type strains of Lactobacillus sp. and Lactococcus sp., and the dependence of their growth and antibacterial activity on three oligosaccharides (OS) – palatinose, inulin and α-cyclodextrin were investigated. All isolated lactobacilli produce antibacterial compounds, which possibly are the bacteriocins of Lactobacillus casei ATCC334 strain. Results of growth analysis with different OS revealed that part of lactobacilli isolated from yogurts can effectively ferment inulin and may be used for the development of synbiotics. Palatinose and Lactobacillus acidophilus could be used as symbiotics with effective antibacterial activity. One of the types of Lactococcus sp. strains can assimilate palatinose and α-cyclodextrin, so they both can be used as components of synbiotics with the investigated lactococci. Results of this analysis suggest that the investigated isolated and type strains of Lactobacillus sp. and Lactoccocus sp. can be useful as probiotics in the development of synbiotics. Together with prebiotics – palatinose, inulin and α-cyclodextrin, the synbiotics, which could regulate not only the growth of beneficial bacteria in the gastrointestinal tract, but also their antibacterial activity, can be created.
The present study was undertaken to evaluate the effects of divercin, a bacteriocin produced by lactobacilli strain Carnobacterium divergens AS7, on the microflora status under in vitro conditions and on nutrient retention and nitrogen-corrected apparent metabolizable energy (AMEN ) of divercin in an in vivo trial on broiler chickens. Low (DL) 200 AU·ml1 (0.05% of the liquid divercin prepatation), and high (DH) 1600 AU·ml-1(0.4% of the liquid divercin prepatation) doses of divercin were used in both trials. In the in vitro trial divercin at concentration, 1600AU ml-1 of divercin had stronger antibacterial effects as compared with 200 AU·ml-1. In the crop and ileal digesta, the DH treatment was characterized by the lowest lactic acid bacteria (LAB) and coliform bacteria counts (0.4-0.8 log cycle reduction). There were no differences in nutrient retention between treatments. Salinomycin and divercin supplementation tended to increase fat digestibility and N retention. However, the highest AMEN were obtained in the DL treatment. The results of both studies show positive effects of divercin in terms of reduction of microbial populations isolated from the gastrointestinal tract (GIT) of broiler chickens as well as improvement in AMEN. The presented data may suggest that bacteriocin derived from Carnobacterium divergens AS7 could play a role in controlling the microbial ecosystem in the broiler chicken GIT.
The purpose of this research was to evaluate the probiotic potential of an capsulated Streptococcus thermophilus CHCC 3534 strain. The strain tolerates 0.4% oxgall (bile) and was sufficiently resistant to pH as low as 2.5 for 3 hours of exposure. The strain demonstrated high adherence to human intestinal mucus, and showed unique resistance to different antibiotics. Crude extracts of S. thermophilus CHCC 3534 contained a diffusible antimicrobial compound "bacteriocin" with a broad spectrum that inhibited the growth of closely related lactic acid bacteria and a number of food spoilage bacteria including Salmonella typhimurium and Staphylococcus aureus. The bacteriocin was heat stable, resistant to pH, inactivated by proteolytic enzymes, and resistant to á-amylase and lipase. A SDS-PAGE analysis of the partially purified bacteriocin revealed one component with a molecular weight ranging from 14.4 to 18.4 kDa. The strain may have industrial significance and represents an interesting candidate for use in biopreservation, probiotic food formulations and in the control of spoilage caused by food borne pathogens.
The aim of the present paper was to determine the effect of bacteriocins produced by Lactobacillus strains isolated from pickled vegetables on Gram-negative pathogenic rods. The antibacterial effect of bacteriocins was determined with the diffusion method, employing the well technique. Incubation was carried out for 24 hours, under the optimum conditions for test strains, and then growth inhibition zones around wells were observed. The results obtained show that individual Lactobacillus strains produce antibacterial substances - bacteriocins, characterized by different activity towards selected strains of Yersinia enterocolitica, Salmonella E. coli O 157.H7 and E. coli K88. Test strains were more sensitive to bacteriocins synthesized by Lactobacillus plantarum, as their growth was inhibited at the activity level 4-32 AU/mL. Bacteriocins of Lactobacillus brevis strains inhibited their growth at 128 and 256 AU/mL.
The work describes purification and biochemical characterization of two inducible antimicrobial peptides from the hemolymph of Galleria mellonella. The peptides were isolated by a sequence of reversed-phase chromatography steps from the hemolymph of larvae immunized with viable bacteria. The first peptide is a member of the cecropin family while the second one is rich in proline residues and has a unique se­quence.
A bacteriocin divercin was produced in batch cultures by Carnobacterium divergens. The bacteria were grown in the liquid MRS media containing enzymatic hydrolysates of whey, casein or malt roots as organic nitrogen sources. The divercin production was greatly affected by the medium composition. The highest divercin activity (12,800 AU/mL), measured by the critical dilution assay using C. piscicola as an indicatory microorganism, was obtained in the medium containing whey, casein hydrolysates, and glucose. Omission of glucose in this medium delayed the divercin biosynthesis only for 5 h. The medium developed was more efficient than the MRS medium used commonly for the bacteriocin production.
The reference strain Yersinia enterocolitica 0:3 - 44 as well as 12 other strains isolated From swine at the Veterinary Hygiene Research Station (VHRS) in Łomża were studied. At 25°C for 24 h the reference strain produced an antibiotic-like substance - bacteriocin. Its amount contained in 4.2 ml in TSB broth medium inhibits the growth of sensitive tested strains, while a concentration of 4,5 ml inhibits also the resistant ones. The bacteriocin synthesized by the reference strain is sensitive to proteolytic enzymes- papain and trypsin when undiluted or only at concentration of 10-1.
Background. Enteroccocci occur and may compete well in fermented sausages and Enterococcus faecium represents that species of the lactic acid bacteria which can be found in the fermented sausages. The representatives of this species can produce bacteriocins with predominant anti-listerial effect. Therefore, the effect of enterocin (Ent) 4231 produced by Enterococcus faecium CCM 4231 strain with probiotic properties was tested in a dry fermented salami Puchov (Slovak product) experimentally inoculated with L. innocua Li1 strain (107 cfu/ml). Material and methods. The bulk salami mixture was prepared in the pilot plant and 2.5 kg for each of three trials were transferred to the laboratory for the experiments. Three independent trials were conducted, each comprising then five salami samples (0.500 g). Trial A (reference control) involved only untreated salami mixture. Trial B represented salami mixture inoculated with Listeria innocua Li1 (107 cfu/ml). For trial C, Ent 4231 possessing activity 6400 AU/ml was added into the salami mixture inoculated with L. innocua Li1 (LilEnt). The mixtures were stuffed into collagen casings and the fiat shape salamis were transferred back to the pilot plant and treated according to conditions typical for this product and stored for 4 weeks. Results. The initial number of L. innocua Li1 in the inoculated salami mixture was 104 cfu/ml. Aft er Ent 4231 addition, the count of Listeria detected in the salami samples inoculated with Li1 and treated with Ent 4231 was 3.64 ±0.14 cfu/ml; difference 0.40 logarithmic cycles was noted between Li samples and Li /Ent samples. On day 2, the difference 1.86 log cycles was noted between Li1 and IM Ent samples. Although, in weeks 3 and 4, slight increase in Li1 cells was determined in Li salamis, the difference in the detection of Li1 cells in Li salamis and Li/Ent samples was even higher than that immedially after Ent addition (difference 2.30; 2.48 log cycles). Bacteriocin activity itself was not recovered from Li/Ent salamis. The pH of the all salamis was almost at the same level. Water activity and water content were not influenced. Conclusion. Addition of Ent 4231 during processing of salami Puchov experimentally inoculated with L. innocua Li1 has lead to decrease of Li1 cell growth, although the bacteriocin activity of Ent itself was not possible to detect in salami samples. The pH value, water activity, as well as sensory character of the final products were not negatively influenced.
This article is an overview of literature addressing edible fi lms and substances introduced to fi lms in order to impart them the antimicrobial activity. It describes natural polymers applied for the production of food packages and active substances of natural origin added to them, including: bacteriocins, enzymes, oils, and plant extracts. Further discussion refers to chitosan – a polysaccharide used for fi lm formation and characterised by strong antibacterial and antimycotic properties.
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