The effect of immobilization of probiotic Lactobacillus reuteri DPC16 in sub-100 μm microcapsule on food-borne pathogens.

The aim of this study was to evaluate whether immobilizing a probiotic strain Lactobacillus reuteri DPC16 in chitosan-coated alginate microcapsules affected their inhibitory performance against food-borne pathogens. The probiotic strain was encapsulated in sub-100 μm alginate microspheres which were further coated with chitosan. This type of probiotic microcapsules was investigated in a co-culture model for its effect against two food-borne pathogenic bacteria. The results confirmed the comparable inhibitory performances between the planktonic and the microencapsulated DPC16 in terms of the medium acidification and the reuterin production in the presence of sufficient nutrients. However, if an infertile condition was present, in which energy source was limited, the planktonic DPC16 tended to instantly accumulate a higher concentration of reuterin but at the cost of substantial viability loss, whereas immobilization in the chitosan-coated alginate microcapsules extended the survival of DPC16, albeit with a significantly lower reuterin production. In conclusion, no attenuated antimicrobial effect was observed for the immobilized DPC16 in the co-culture model. Microencapsulation rendered an enhanced protection on the embedded probiotics, but it may also induce an altered availability of substrates to those microorganisms.