Enteropathogenic Escherichia coli (EPEC) is one of the etiological agents that causes diarrhea in weaning pigs. In this study, we report that mutating both relA and spoT genes in EPEC E2348/69 can promote bacterial clearance in porcine gastrointestinal tract (GIT). Our experimental analyses showed that an E2348/69 ΔrelAΔspoT mutant strain was not detected in porcine feces after 1 day post-infection (dpi), whereas its parental strain was continuously detected in porcine feces within 10 dpi. Histologic assessment revealed that the mutant strain was unable to induce moderate pathologic lesions in porcine GIT when compared to those with the wildtype strain. Taken together, our data suggest that the relA and spoT genes in EPEC play an important role in bacterial survival and pathogenesis in porcine GIT.

The pace of development of Pickering emulsions stabilized by food-derived particles such as starches and proteins has recently soared to replace conventional emulsions using a large amount of chemical emulsifiers. The protein-stabilized emulsions cannot be transported to small intestine due to its degradation in stomach condition. The starch-stabilized emulsions have a low colloidal stability because of their large size, so they cannot be applied to beverages. In this study, to increase the colloidal stability of starch-stabilized emulsions, starch nanocrystals (SNC) obtained by sulfuric acid hydrolysis were used to stabilize emulsions, and ultrasonic treatment was added to further increase the colloidal stability. An oil-soluble dye (Nile Red) was used to visualize changes in the lipid phase during digestion. Lipid-labeled Pickering emulsions were passed through a simulated gastrointestinal tract consisting of mouth, stomach, and intestinal phases, and changes in lipid location and morphology were monitored using confocal laser scanning microscopy. The lipid droplets were slightly enlarged in the mouth condition, highly flocculated in the gastric condition, and completely digested in the small intestine condition. Our results show that the additional ultrasonication to the SNC-stabilized emulsions resulted in enhanced colloidal stability, and the SNC-stabilized emulsions produced by the above process were stable in the mouth and stomach conditions and completely digested in the small intestine condition. So, the SNC-stabilized emulsions produced through this study could be effectively applied to functional beverages as a chemical emulsifier-free delivery systems.