Effect of microencapsulated Lactobacillus reuteri under simulated gastric conditions and its inhibition on Listeria monocytogenes

Food-borne diseases (FDB) are responsible for causing approximately 600 million illnesses and 420,000 deaths per year. Biologically related FBDs are typically associated with ubiquitous microorganisms, with bacteria such as Li. monocytogenes, Escherichia coli, Salmonella and Staphylococcus aureus being frequently implicated. The use of probiotics is limited by adverse conditions, that can impair the stability of La. reuteri and the evaluation of its probiotic properties and effects on pathogenic bacteria. Therefore, it is crucial to develop effective strategies to protect probiotics during their use. This study was conducted aiming to determine the effect of microencapsulation by spray drying technique on the probiotic viability of La. reuteri on Li. monocytogenes under simulated gastric conditions. The research involved reconstituting, planting, and inoculating La. reuteri and Li. monocytogenes; determining fermentation kinetics; conducting spray drying microencapsulation; studying and characterizing of microencapsulation; testing for exopolysaccharides production; conducting temperature tests; assessing exposure to gastric conditions; and conducting antibiotic susceptibility and inhibition tests. Such investigations allowed the establishment of the exponential phase in Probiotic (PRO) culture medium at 18 h and in De Man, Rogosa and Sharpe agar (MRS) medium at 12 h, exopolysaccharide production positive and growth at different temperatures (1.95x1013 CFU/ml and 2.16x1012 CFU/ml), survival against gastric conditions (greater than 108 CFU/ml) and inhibitory effect of La. reuteri on Li. monocytogenes (halos larger than 2 mm). The probiotic La. reuteri microencapsulated in a binary matrix composed of inulin and maltodextrin expresses probiotic properties against Li. monocytogenes, which is responsible for FBD and great stability after undergoing simulated gastric conditions.