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Pediococci are lactic acid bacteria widely used as starter cultures in the food industry, which produce lactic acid and bacteriocins (pediocins) possessing significant antilisterial potential. This research aimed to investigate the antimicrobial activity of three Pediococcus strains (Pediococcus pentosaceus, Pediococcus acidilactici and Pediococcus damnosus) against three Listeria strains (Listeria monocytogenes, Listeria innocua and Listeria ivanovii) to determine the growth characteristics and kinetic parameters during the process of co-cultivation at 37 ± 1°C. The results demonstrated that P. pentosaceus possessed a bacteriostatic effect on L. monocytogenes, but a bactericidal effect on L. innocua and L. ivanovii, and on the 60-th h no viable cells of both pathogens were detected. P. acidilactici demonstrated a strong bactericidal effect on the three Listeria strains, as L. monocytogenes was completely inhibited on the 48-th h and L. innocua and L. ivanovii were inhibited on the 60-th h of co-cultivation. In contrast, P. damnosus showed only a bacteriostatic effect on the three pathogens tested. Therefore, the strains P. pentosaceus and P. acidilactici can be successfully applied in the food industry as biopreservatives and as means to improve the food safety by inhibition of Listeria spp., which are among the most common pathogens in food products of animal origin. [ABSTRACT FROM AUTHOR]

An important step in the development of successful technological schemes for production of yogurt and other functional foods is the selection of appropriate Lactobacillus strains with useful properties that are resistant to antibiotics and bacteriocins. In the present study eleven Lactobacillus strains were isolated from fourteen homemade Bulgarian and Italian yogurts. The isolates were identified as Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) by 16S rDNA sequence analysis. The results from comparative 16S rRNA gene sequence-based phylogenetic analysis revealed 92-99% pairwise similarity of the isolates to the reference L. bulgaricus strains. The antimicrobial activity, antibiotic susceptibility and nisin resistance of the isolated L. bulgaricus strains were examined. Bulgarian L. bulgaricus strains 3-BG, 5-BG and 8-BG were characterized by highest antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus ATCC 25923, Listeria monocytogenes NBIMCC 8632, Listeria ivanovii ATCC 19119, Listeria innocua ATCC 33090, Enterococcus faecalis ATCC 19433 and Enterococcus faecuim ATCC 19434. L. bulgaricus 8-BG was active also against the Gram-negative bacteria Pseudomonas aeruginosa ATCC 9027, Proteus vulgaris ATCC 6380, Salmonella enteritidis ATCC 13076, Salmonella abony NTCC 6017 and Escherichia coli ATCC 25922. In contrast, Italian L. bulgaricus strains demonstrated low antimicrobial activity. Bulgarian L. bulgaricus strains showed moderate sensitivity or resistance to most of the antibiotics used in the screening, while Italian L. bulgaricus strains were sensitive. Bulgarian L. bulgaricus strains 1-BG and 6-BG were resistant to 10 and 13 of a total of 24 antibiotics tested, respectively. Nisin resistance test showed that 10 of a total of 11 L. bulgaricus strains were highly sensitive to nisin (MIC values varying from 0.078 mg/mL to 0.156 mg/mL), except of Italian strain L. bulgaricus 6-IT which was resistant to nisin. [ABSTRACT FROM AUTHOR]

This study aims to investigate the chemical composition, antioxidant, and antimicrobial activity of Citrus aurantium L zest essential oil. The identification of the chemical compounds was done using chromatography analysis. The antioxidant activity was studied by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Results showed that the main components of the essential oil were limonene (85.22%), β-myrcene (4.3%), and α-pinene (1.29%). Regarding the DPPH radical scavenging ability, the zest essential oil showed higher activity than limonene. The antimicrobial activity of the essential oil against pathogenic [Staphylococcus aureus NBIMCC 3703, Salmonella sp. (clinical isolate), Pseudomonas aeruginosa NBIMCC 1390, Bacillus subtilis NBIMCC 1208, Escherichia coli NBIMCC 3702] microorganisms by disc-diffusion method was examined. Gram-positive bacteria were more sensitive to the oil (inhibition zones being between 9 and 12.5 mm) and the minimum inhibitory concentration was more than 600 ppm; Gram-negative bacteria were less sensitive. The obtained essential oil displayed promising results for its application as a biopreservative agent. [ABSTRACT FROM AUTHOR]

• Mayonnaise was preserved by dill and basil essential oils, and L. plantarum. • Dill and basil essential oils exhibited potent antimicrobial activity. • Undesired microflora in mayonnaise was suppressed by essential oils and L. plantarum. • L. plantarum , dill and basil oils could serve as bio preservative agents in foods. In this study, different variants of egg-free mayonnaise containing free and immobilized Lactobacillus plantarum LBRZ12 cells and essential oils taken from basil and dill were prepared. The composition and antimicrobial properties of essential oils were investigated. The main constituents of basil oil were methyl chavicol (36.81%), methyl eugenol (20.40%), β -linanool (14.35%), eugenol (10.55%), and L(-)-carvone (39.05%), whereas dill oil contained mostly d -limonene (21.11%) and α -phellandrene (22.68%). The essential oils exhibited strong antimicrobial activity against all test-microorganisms. The mayonnaise variants were kept refrigerated for 40 days and changes in pH, concentration of viable cells of lactobacilli, microbiological, and organoleptic characteristics were monitored. The pH decreased from 6.5 to 4.5 over the period of storage. The number of undesired microflora in mayonnaise preserved with lactobacilli and essential oils decreased significantly (0 after the 20th day) indicating their effectiveness as biological preservatives. The mayonnaise variants demonstrated pleasant organoleptic characteristics, thus meet customers' requirements. [ABSTRACT FROM AUTHOR]