Encapsulation of putative probiotic Lactiplantibacillus plantarum Lbio1 in sodium alginate matrix: in vitro assessment of its biofunctional properties and survivability

The increasing demand for functional foods has stimulated research on probiotic strains with health-promoting properties. This study investigated the biofunctional traits of the putative exopolysaccharide (EPS)-producing strain Lactiplantibacillus plantarum Lbio1 and evaluated its survival, both free and encapsulated, under simulated gastrointestinal conditions. Safety assessment indicated the absence of haemolytic and gelatinase activities and susceptibility to most tested antibiotics. The strain tolerated acidic pH (2.0) and bile salts (0.3% w/v) with survival rates of 72 and 83%, respectively, and exhibited bile salt hydrolase activity. The strain also grew in 0.1% (v/v) phenol. Adhesion-related properties included high auto-aggregation (92%) and co-aggregation with pathogenic strains (Escherichia coli ATCC 25522, Staphylococcus aureus ATCC 43300, and Micrococcus luteus ATCC 49732), ranging from 43.9 to 71.5%, as well as a biofilm formation capacity, despite exhibiting low hydrophobicity (16%). Cholesterol assimilation reached 82%. The EPS produced by Lbp. plantarum Lbio1 was a high molecular weight heteropolymer composed of glucose and galactose. The encapsulation of Lbp. plantarum Lbio1 in alginate beads (≈ 3 mm, 91% efficiency) efficiently loaded cells, as observed by scanning electron microscopy, and enhanced their survival under simulated gastrointestinal stress. Encapsulated cells retained viability above 10⁶ CFU/g for 34 days at refrigeration temperature, despite a viability loss of approximately 1 log CFU per week. These findings highlight the probiotic potential of Lbp. plantarum Lbio1 and the efficiency of encapsulation in improving bacterial cell survival.