The exopolysaccharide (EPS)-producing Lactobacillus plantarum (renamed as Lactiplantibacillus plantarum) LBIO1, LBIO14 and LBIO28 strains, isolated from fermented dairy products typical from Algeria, were characterized to evaluate the impact of the polymers in milk fermentations. Their genomes revealed the presence of two complete eps clusters of the four described for the reference strain WCFS1. Besides, the three strains presented identical sequences of eps3 and eps4 clusters, but LBIO1 and LBIO28 harbour three genes belonging to eps2 which are absent in the LBIO14 genome. The EPS purified from fermented skim-milks manufactured with the strains showed identical nuclear magnetic resonance (¹H-NMR) and size exclusion chromatography coupled with a multiangle laser light scattering detector (SEC-MALLS) profiles for polymers LBIO1 and LBIO28, whereas LBIO14 EPS was different due to the lack of the high-molecular weight (HMW)-EPS and the absence of specific monosaccharide’s peaks in the anomeric region of its proton NMR spectrum. The presence of the HMW-EPS correlated with optimal sensorial-physical characteristics of the fermented skim-milks (ropy phenotype). Their microstructures, studied by confocal scanning laser microscopy (CSLM), also showed differences in the organization of the casein-network and the distribution of the bacteria inside this matrix. Therefore, the strain LBIO1 can be proposed for the manufacture of dairy products that require high whey retention capability, whereas LBIO28 could be applied to increase the viscosity.

Using culture enrichment methods, 100 strains of bacilli of lactic acid bacteria (LAB) were isolated from honeybee Apis mellifera intermissa and fresh honey, collected from apiaries located in the north-east of Algeria. Amongst all of the isolated LAB, 19 selected strains were closely affiliated to four species—Fructobacillus fructosus (10), Apilactobacillus kunkeei (5), Lactobacillus kimbladii and/or Lactobacillus kullabergensis (4)—using phylogenetic and phenotypic approaches. The in vitro probiotic characteristics (simulated gastrointestinal fluids tolerance, autoaggregation and hydrophobicity abilities, antimicrobial activity and cholesterol reduction) and safety properties (hemolytic activity, antibiotic resistance and absence of biogenic amines) were evaluated. The results indicated that some strains showed promising potential probiotic properties. In addition, neither hemolytic activity nor biogenic amines were produced. The carbohydrate fermentation test (API 50 CHL) revealed that the strains could efficiently use a broad range of carbohydrates; additionally, four strains belonging to Apilactobacillus kunkeei and Fructobacillus fructosus were found to be exopolysaccharides (EPS) producers. This study demonstrates the honeybee Apis mellifera intermissa and one of her products as a reservoir for novel LAB with potential probiotic features, suggesting suitability for promoting host health.