Effect of microencapsulation on the viability of probiotic bacteria under storage and simulated gastrointestinal conditions

Abstract

Nowadays, microencapsulation through different techniques and within different polymers gets a lot of attention as a promising technology for lactic acid bacteria protection. The emphasis itself comes firstly from the advantages of these later, including production of nutrients and co-factors, competition with pathogens and stimulating the host immune response, and secondly from its ability to cover these living cells, giving them more chances to exert their health benefits, since they remain far from the deleterious environmental factors during both processing and digestion, thus remaining viable till reaching colon where they act. In this context, we underlined our aims throughout this study by isolation of lactic acid bacteria from the Algerian traditional cheese “Klila”, then selection of bacteria with the best probiotic and technological properties. The selected bacteria were encapsulated in sodium alginate mixed to different polymers and viability under storage at 4°C and under gastrointestinal conditions was tested. Our results indicated that “Klila” contains different species of lactic acid bacteria, as confirmed by genetic identification through 16S rRNA sequencing, namely Lb. plantarum as a dominant species, Lb. pentosus, Lb. casei and Lb. brevis. Few isolates are considered to have some technological traits principally acidifying activity and proteolytic activity. No isolate exhibited lipolysis or exopolysaccharide production. Antagonism was tested against E. coli ATCC 25422, S. aureus, B. subtilis, L. monocytogenes, and Salmonella sp. All our bacteria showed antagonist activity against at least one pathogen, while two of the isolates displayed inhibition activity against all tested organisms (Lb. plantarum Q18 and Lb. casei B1). In addition, resistance was tested against two antibiotic groups: cell wall inhibitors (Penicillin G, Amoxicillin) and protein synthesis inhibitors (Streptomycin, Gentamycin), and Colistin sulfate. Most of our isolates were sensitive to the five antibiotics used with almost equal diameters, where the largest one (27.75 ± 0.35 mm) was obtained with Q28 against Gentamycin and the smallest one (6 mm) with Q8 against Colistin sulfate. Results also showed that Lb. casei B1 and Lb. plantarum Q18 as selected strains exhibited good auto-aggregation and adhesion properties in addition to their tolerance to gastrointestinal simulated conditions and bile salts.