Probiotic Spores of Shouchella clausii SF174 and Displayed Bromelain Show Beneficial Additive Potential

Probiotics have health-beneficial properties mainly due to either a direct action on the host or the modulation of the host microbiota. Health-beneficial properties have also been associated with a variety of plant-derived molecules, widely used as dietary supplements. This study explores the possibility of combining the actions of probiotics and of plant-derived molecules by developing beneficial, probiotic-carrying, heterologous molecules. To this extent, spores of SF174, a well-characterized probiotic strain of Shouchella clausii (formerly Bacillus clausii), were used to bind bromelain, a plant-derived mixture of endopeptidases with beneficial effects. Probiotic spores displaying bromelain maintained their antioxidant activity and acquired the endopeptidase activity of the heterologous molecule. The endopeptidase activity was stabilized by the interaction with the spore and largely preserved from degradation at simulated gastric conditions. Under conditions mimicking those encountered in the intestine, as well as upon spore germination, active bromelain was released from the spore surface. The in vitro results reported in this study support the idea that probiotics carrying beneficial heterologous molecules combine the health properties of the probiotic with those of the delivered molecule and pave the way for the development of a novel class of functional probiotics.