Comparative analysis of the adhesion capacity of lactic acid bacteria and bifidobacteria isolated from traditional dairy products using a Сaco-2/HT29-MTX co-culture model

Abstract

Abstract The aim of the present study was to evaluate the adhesive properties of lactic acid bacteria and bifidobacterial strains isolated from traditional fermented dairy products of Kazakhstan using an in vitro model of the human intestinal epithelium (Сaco-2/HT29-MTX). The investigated strains were isolated from shubat, koumiss, kurt, and raw camel milk. A total of 11 bacterial strains were included in the study, comprising 7 strains of lactic acid bacteria (genera Lactobacillus and Lactococcus) and four strains of Bifidobacterium crudilactis isolated from shubat (fermented camel milk), koumiss (fermented mare’s milk), kurt (dried fermented dairy product), and raw camel milk. Microbial identification was performed by 16S rRNA gene sequencing, revealing sequence similarity levels ranging from 99.71% to 100.0%. Adhesion activity was assessed based on optical density measurements and adhesion index values. The results demonstrated substantial differences in adhesion capacity among the lactic acid bacterial strains. The highest adhesion activity was observed for Lactobacillus crustorum 8-9M and Lactococcus lactis subsp. lactis 7-8M, whereas the lowest was detected in Lactobacillus pontis 6-12M. Among the bifidobacteria, Bifidobacterium crudilactis 7-5C exhibited the greatest adhesion capacity, while strain 7-6C showed no detectable adhesion activity. The obtained results indicate pronounced strain-specificity of the adhesive properties of the investigated microorganisms and allow the identification of promising cultures with high probiotic potential.