Determination of the Antimicrobial Effects of Synbiotic Kefir Produced from Buffalo Milk Enriched with Galactooligosaccharides and Inulin

In this study, the effects of fat content (0.5 and 3.5%), prebiotics (galactooligosaccharides [GOS] and inulin), production method (traditional and commercial), and storage period (21 days at 3 ± 1 °C) on the antimicrobial activity of synbiotic kefirs produced using buffalo milk against certain pathogenic microorganisms (<i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i>, <i>Enterococcus faecalis</i>, <i>Listeria monocytogenes</i>, <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli</i>, and <i>Candida albicans</i>) were determined. Variations in fat content significantly affected antimicrobial activity against <i>E. faecalis</i> (<i>p</i> < 0.01), <i>L. monocytogenes</i> (<i>p</i> < 0.01), and <i>E. coli</i> (<i>p</i> < 0.01); the production method influenced <i>S. aureus</i> (<i>p</i> < 0.01), <i>B. subtilis</i> (<i>p</i> < 0.05), <i>E. faecalis</i> (<i>p</i> < 0.01), <i>E. coli</i> (<i>p</i> < 0.01), and <i>C. albicans</i> (<i>p</i> < 0.01), while prebiotic addition affected <i>S. aureus</i> (<i>p</i> < 0.01), <i>L. monocytogenes</i> (<i>p</i> < 0.05), <i>E. coli</i> (<i>p</i> < 0.05), and <i>C. albicans</i> (<i>p</i> < 0.01). The storage period had a significant effect (<i>p</i> < 0.01) on all examined pathogens, and antimicrobial activity increased as storage time progressed. In general, the use of commercial culture and prebiotics in kefir production enhanced antimicrobial activity. The effects of inulin (on <i>S. aureus</i>, <i>C. albicans</i>) and GOS (on <i>L. monocytogenes</i>, <i>E. coli</i>, <i>C. albicans</i>) varied across microorganisms. Based on the average zone diameters produced by the kefir samples: The highest activity against <i>S. aureus</i> was observed in inulin-containing and cultured samples, against <i>B. subtilis</i>, it was observed on the seventh day in cultured samples, against <i>C. albicans</i>, in inulin-containing and cultured samples (on day 21), against <i>L. monocytogenes</i>, in GOS-enriched and 0.5% fat samples, as well as in inulin-added samples (on day 21), against <i>E. faecalis</i>, in 0.5% fat and cultured samples (on day 21), against <i>E. coli</i>, in 3.5% fat, GOS-added, and cultured samples, and against <i>P. aeruginosa</i>, activity was detected on the seventh and 14^th days of storage.