Purpose: To evaluate the probiotic potential of strains isolated from olives to be used as starters for the improvement of the traditional fermentation and the production of a new functional food.
Methods: Seventy-one lactic acid bacterial strains (isolated from olives) were screened for their probiotic potential, following a series of in vitro tests. 17 strains were Leuconostoc mesenteroides, 1 Ln. pseudomesenteroides, 13 Lactobacillus plantarum, 37 Lb. pentosus, 1 Lb. paraplantarum, and 2 Lb. paracasei subsp. paracasei. Lb. rhamnosus GG and Lb. casei Shirota were used as reference strains. All isolates were tested for their survival in simulated gastrointestinal tract conditions, antimicrobial activity (against Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli O157:H7), resistance to 9 antibiotics, Caco-2 surface adhesion and hemolytic activity.
Results: Three Lb. pentosus strains, 4 Lb. plantarum strains and 2 Lb. paracasei subsp. paracasei demonstrated the highest populations (≥ 8 log CFU/ml) after 3 h of exposure at low pH. The majority of the tested strains were resistant to bile salts even after 4 h of exposure. 5 Lb. plantarum and 7 Lb. pentosus strains exhibited partial bile salt hydrolase activity. None of the examined strains exhibited β-hemolytic activity. Variable susceptibility of the strains towards the different antibiotics and their efficiency to adhere to Caco-2 cells was observed. None of the tested strains inhibited the growth of the pathogens.
Significance: The fact that some of the tested strains possess probiotic properties enhances their potential of being used as starter cultures to produce a traditional product with desirable fermentation characteristics and added value.