In-vitro antifungal and anticlostridial activity of lyophilized postbiotics from Lactiplantibacillus plantarum, Lacticaseibacillus casei, and Lactobacillus helveticus strains

Molds and Clostridium species are significant microorganisms responsible for food spoilage and are also considered potential threats to public health. The aim of this study is to determine the antifungal and anticlostridial activities of lyophilized postbiotics obtained from Lactobacillus spp. (Lb. plantarum, Lb. casei, and Lb. helveticus) and to evaluate their pH and titratable acidity values. In addition, the in vitro antimicrobial effects against strains of Aspergillus parasiticus, Penicillium crysogenum, Clostridium sporogenes, and Clostridium tepidum were investigated (minimum inhibitory (MIC), minimum bactericidal (MBC)/minimum fungicidal concentration (MFC), and zone of inhibition diameters). The pH values of the postbiotics obtained from Lactobacillus spp. ranged from 3.98 to 4.58, while their titratable acidity values ranged from 1.28 - 9.38 g lactic acid/100 mL. The MIC, MBC/MFC, and inhibition zone values of Lactobacillus spp. against the specified mould and Clostridium strains were found to range from 12.5 mg/mL, 50–100 mg/mL, and 17.36–24.25 mm, respectively. In conclusion, lyophilized postbiotics derived from Lactobacillus strains demonstrated strong antifungal and anticlostridial activities, with their efficacy increasing in a concentration-dependent manner.