Assessing the growth-inhibitory activity of postbiotics of Lactobacillus spp. against Staphylococcus aureus under in vitro circumstances and food model

Postbiotics are soluble metabolites that are liberated from the structure of lysing bacteria or are produced by live bacteria; these byproducts give the host increased biological activity and certain physiological effects. In the current study, the anti-Staphylococcus properties of postbiotics isolated from Lactobacillus acidophilus,L.paracasei,and L.plantarum were investigated in vitro, and pasteurized milk. Potential activity of postbiotics was performed via agar-disk diffusion method. Besides, the effect of heat and pH on the postbiotics antibacterial activity was measured via the agar-well diffusion method. To determine the antioxidant effect and the free radical scavenging potential of the postbiotics, 1,1-Diphenyl-2-picrylhydrazyl (DPPH) method was utilized. The postbiotics chemical composition was identified via gas chromatography-mass spectrometry. The antibacterial activity was mainly associated with lactic acid, laurostearic acid, and isopropylidene-3,3-dimethyl. Also, postbiotics showed strong antioxidant activity. Postbiotics derived from L.plantarum showed the highest antioxidant properties compared to L.paracasei and L.acidophilus. Lower minimum effective concentrations of postbiotic were altered in food model, and substantially, a low minimum effective( MEC) concentrations index (15 mg/mL) was identified for postbiotic of L.plantarum. The Lactobacillus spp. postbiotic, in particular L.plantarum, may have useful functional characteristics (possible antibacterial and antioxidant) in in vitro and food model.