Selection of lactic acid bacteria from dairy matrices with antifungal activity to be used as biopreservative adjunct cultures

Abstract

This study aimed to assess the technological, safety, antibiotic resistance, and antifungal properties of 35 lactic acid bacteria (LAB) from Sicilian dairy products. Sixteen Lactiplantibacillus plantarum isolates produced diacetyl, and 30 LAB isolates showed proteolytic activity, suggesting technological potential. All isolates presented weak milk acidification capacity. Aminopeptidase activity varied, with PepX (5/35) and PepN (2/35) showing better activity on Lactiplantibacillus fermentum, Lactobacillus sp. and L. plantarum strains, indicating species-specificity. None of the isolates showed hemolytic, gelatinase, DNase, or coagulase activity. Most were resistant to oxacillin, tetracycline, rifampicin, and vancomycin. Regarding antifungal activity, L. plantarum (n = 10) and Lactiplantibacillus sp. (n = 1) isolates inhibited Aspergillus niger and Penicillium chrysogenum, while L. rhamnosus (n = 5) strains were active against P. chrysogenum. Overall, Lactiplantibacillus isolates, particularly L. plantarum from donkey milk, showed promising technological traits, safety, and potential as bioprotective cultures. These findings support the search for new strains with improved characteristics and technological applications.