Safety assessment of potential probiotic lactic acid bacteria strains Pediococcus acidilactici SY21 and Pediococcus acidilactici SY22

Pediococcus acidilactici SY21 and Pediococcus acidilactici SY22 exhibit anti-inflammatory activity; however, their safety has not been evaluated. The suitability as probiotic strains were evaluated by using phenotypic and genotypic analyses. Indole production, urease activity, mucin degradation, bile salt hydrolase activity, β-hemolysis, and gelatin liquefaction activity were not found. The minimum inhibitory concentrations of the nine antibiotics tested were below the cut-off values recommended by the European Food Safety Authority, except for kanamycin and clindamycin in P. acidilactici SY21 and kanamycin in P. acidilactici SY22. After confirming that the genetic basis of antibiotic resistance exceeded the cut-off value, all isolates showed intrinsic resistance. P. acidilactici SY21 and P. acidilactici SY22 did not produce biogenic amine, and β-glucuronidase activity. Neither strain was cytotoxic to Caco-2 cells. Antibiotic resistance or virulence genes were not detected with whole-genome sequencing. This study demonstrated the safety of the P. acidilactici SY21 and P. acidilactici SY22 strains as probiotics.