As potential probiotic traits of human milk-isolated bacteria have increasingly been recognized, this study aimed to evaluate the probiotic properties of bacteriocin-producing Enterococcus faecium strains isolated from human milk and colostrum. Among 118 human milk- and colostrum-isolated lactic cocci, only 29 were identified as Enterococcus. Of these, only four Enterococcus faecium isolates exhibited bacteriocigenic activity against several pathogenic Gram-positive bacteria, including Listeria monocytogenes. These isolates exhibited high acid (up to pH 3.0) and bile tolerance (0.5% oxgall) in simulated gastrointestinal conditions, demonstrating their ability to survive through the upper gastrointestinal tract. All of the E. faecium strains were shown to be sensitive to most of the antibiotics including vancomycin, tetracycline, rifampicin, and erythromycin, while they were resistant to kanamycin and chloramphenicol. None of the strains showed any virulence (gelE, agg2, clyA, clyB, clyM) and antibiotic resistance genes (vanA, vanB, ermB, tetM, and aac(6')-le-aph(2″)-la). In addition, all the strains were able to assimilate cholesterol, ranging between 25.2-64.1% and they exhibited variable adherence (19-36%) to Caco-2 cells. Based on the overall results of this in vitro study, four of the E. faecium strains isolated from human milk and colostrum can be considered as promising probiotic candidates; however, further in vivo evaluations are required.
- MeSH
- antibakteriální látky farmakologie MeSH
- antibióza MeSH
- bakteriální adheze MeSH
- bakteriální léková rezistence MeSH
- bakteriociny metabolismus MeSH
- Caco-2 buňky MeSH
- cholesterol metabolismus MeSH
- Enterococcus faecium účinky léků genetika izolace a purifikace metabolismus MeSH
- kolostrum mikrobiologie MeSH
- lidé MeSH
- Listeria monocytogenes fyziologie MeSH
- mateřské mléko mikrobiologie MeSH
- mikrobiální testy citlivosti MeSH
- probiotika * MeSH
- žaludeční šťáva MeSH
- žlučové kyseliny a soli farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Some studies report that hormone melatonin can be found in human milk, but the daily variation in colostrum melatonin is not available. This study verified the effects of milk collection time (diurnal/nocturnal) on colostral melatonin levels and the ability of this hormone to modulate colostral phagocyte activity. Colostrum samples were collected from 30 mothers during the day and night, for a total of 60 samples. We determined melatonin levels in colostrum and superoxide release and bacterial killing by colostral phagocytes. Melatonin levels were higher in colostrum samples collected at night. Phagocytes in nocturnal colostrum samples increased spontaneous superoxide release. In diurnal colostrum samples, mononuclear (MN) phagocytes increased superoxide release when exposed to enteropathogenic Escherichia coli (EPEC), but not polymorphonuclear (PMN) phagocytes. Phagocytes exposed to both EPEC and melatonin had higher superoxide release, independent of phagocyte type and colostrum collection period. Phagocytosis rate was higher in colostrum samples collected at night. In diurnal samples, EPEC killing by MN phagocytes was lower than by PMN phagocytes. Phagocytosis increased significantly in the presence of melatonin in both MN and PMN cells, irrespective of colostrum collection period. In response to melatonin, MN phagocytes from both diurnal and nocturnal samples increased bactericidal activity, whereas colostral PMN phagocytes increased it only in diurnal samples. The melatonin increased in the intracellular Ca2+ levels. The highest intracellular Ca2+ release were found in MN phagocytes diurnal samples. These results confirm that melatonin levels in human colostrum follow a day-night variation and increase phagocytic activity of colostral cells against bacteria.
- MeSH
- biomedicínský výzkum MeSH
- cirkadiánní rytmus MeSH
- dospělí MeSH
- Escherichia coli imunologie MeSH
- fagocytóza MeSH
- fagocyty * imunologie MeSH
- intracelulární "calcium-sensing" proteiny MeSH
- kojení MeSH
- kolostrum * cytologie imunologie mikrobiologie MeSH
- lidé MeSH
- melatonin * metabolismus MeSH
- mladý dospělý MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
