ABSTRACT
Aims: Five Lactobacillus rhamnosus strains (UBU03, UBU06, UBU09, UBU34 and UBU37) with good in vitro probiotic properties, isolated from breast-fed infants, were evaluated for in vitro adhesion, competitive adhesion and immunomodulatory properties. Knowledge of such properties is important when considering specific circumstances when these strains might be used clinically. Methodology and results: The Caco-2 cell line was used for adhesion assays and for competitive adhesion assays against Escherichia coli O157:H7. Lactobacillus rhamnosus GG was used as the reference strain for adhesion assays. The immunomodulatory activities of the five strains were evaluated by determining the levels of the inflammatory cytokines IL-6, IL-12 and TNF-α, and of the immunoregulatory cytokine IL-10, produced by bacterial-activated THP-1 cells after 6, 12 and 24 h of stimulation. In the cell-adhesion assays, all five strains showed high adhesion properties. For UBU09, UBU34 and UBU37, adhesive capacity was higher than that of the reference strain. All strains except UBU03 showed the ability to inhibit adhesion of E. coli O157:H7 to Caco-2 cells. All strains induced IL-6 production but not IL-12 production. UBU03 and UBU09 could induce only one cytokine IL-6. UBU06 and UBU34 could each induce two (IL-6/IL-10 and IL-6/TNF-α, respectively). UBU37 could induce three cytokines (IL-6/TNF-α /IL-10). Conclusion, significance and impact of study: These five probiotic L. rhamnosus strains with high adhesion properties and with different in vitro cytokine induction profiles should be investigated further in different immunological conditions to identify appropriate circumstances for their clinical use.
ABSTRACT
Aims: In this study, lactic acid bacteria (LAB) were isolated from 42 healthy infants and determined for probiotic properties. Twelve LAB isolates with potential probiotic properties were selected and screened for their feasibility of heterologous protein expression by selection of erythromycin sensitive isolates. Methodology and results: One of eleven erythromycin-sensitive LAB isolates identified and designated as Lactobacillus fermentum 47-7 was able to acquire and stable maintain the Escherichia coli-Lactobacillus shuttle vector, pRCEID-LC13.9. Further electrotransformation of L. fermentum 47-7 with the recombinant pLC13.9:LDH-PRO1:GFPuv containing green fluorescent protein (GFP) gene found that recombinant L. fermentum can express GFP. Conclusion, significance and impact of study: The probiotic L. fermentum isolate can be used as host for expression of heterologous proteins and could possibly be further developed as the alternate oral delivery system for various biomolecules for biotechnological application.