Characterization of Lactiplantibacillus plantarum strains isolated from Algerian fruits for probiotic and biotechnological applications

Abstract

Twenty-one lactic acid bacteria (LAB) strains were isolated from Algerian fruits such as white mulberry (Morus alba L.), prickly pear (Opuntia ficus-indica), date (Phoenix dactylifera L.), grape (Vitis vinifera) and fig (Ficus carica). The initial screening showed that ten out of twenty-one strains were tolerant to acid pH and bile salts and were further identified as Lactiplantibacillus (L.) plantarum strains by MALDI-TOF mass spectrometry and 16S rDNA sequencing. The identified strains were then characterized for their surface properties such as self-aggregation, hydrophobicity and biofilm formation. The resulting data were then statistically processed using Principal Component Analysis (PCA), after which only 5 strains were selected for further analysis. These five strains, designated L. plantarum F8, F13, FB23, D21 and M1, were found to be safe and able to adhere to human epithelial colorectal adenocarcinoma Caco-2 cells. In particular, all these strains were active against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 through the production of lactic acid (up to 12 g.l⁻¹) or bacteriocins, namely plantaricins, or their combination. In addition, these strains showed high antioxidant activity against the synthetic free radicals 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis: 3-ethyl-benzothiazoline-6-sulphonic acid (ABTS +) radical. These results demonstrate the importance of these L. plantarum strains for the development of new functional foods and probiotics and as biopreservatives. This study deepens and enriches the knowledge of lactobacilli from plant raw materials by focusing on the functional properties of new strains of L. plantarum isolated from Algerian fruits. In fact, with the growing interest in natural preservatives and probiotics, the results of this study could contribute to the development of new biotechnological products aimed at improving gut health, reducing food-borne illnesses and extending the shelf life of food by preventing spoilage.