Degree

Doctor of Philosophy (PhD)

Department

Nutrition and Food Sciences

Document Type

Dissertation

Abstract

Diarrhea remains the second leading cause of death among children under five globally, about one in five children’s deaths are attributable to it. In recent years,’ probiotics have been used as an alternative therapy measure to manage the situation. A promising delivery method that entraps probiotics in infant formula may help prevent or reduce diarrhea. The overall objectives of this study were to deliver entrapped Lactobacillus Plantarum NCIMB 8826 with maize-legume fortified complementary weaning food to reduce diarrhea and improve the gut microbiota. Both in vitro and in vivo models were used in this study and a mouse (C57BL/6 mice pups) model used for in vivo study was used to model gut health in children. Three different weanimix blends, (1) MCPPm (Maize: Cowpea: Peanut: Powdered milk), (2) MCP (Maize: Cowpea: Peanut), and (3) MC (Maize: Cowpea), were used for the in vitro study. LP were entrapped on all three blends and tested for survival and viability under simulated gastrointestinal fluid (SGF) conditions. Free cells were the control. The three weaning blends offered a protective shield to entrapped LP with less than 1 log cycle reduction of viable cells, while the control (free LP cells) had a reduction of 5.15 log cycle after 180 min of exposure to SGF (pH 2.5) conditions. MCPPm was selected for the animal study because it contains milk protein, which is known as a complete protein source and has all essential amino acids. Weanling C57BL/6 mice were gavage with Citrobacter rodentium and fed with entrapped LP (MCPPm-LP) either 3 days before (prevention) or 3 day after (cure) the infection. The control was mice infected with the same level of C. rodentium and fed the same diet without LP. The mice were euthanized 10-day post infection and their colonic tissues, spleen and cecal content were evaluated. Control mice had mucosal and submucosal inflammation with thickening of the mucosa. The colonic epithelium, of LP treated mice were covered with a gel forming mucus layer, which restricted access of C. rodentium ability to attach and efface. Mice fed with entrapped LP showed unremarkable findings. For example, there was a numerical elevation in short-chain fatty acids with both entrapped LP groups. The operational taxonomic units (OTUs) had an abundance of Bacteroidetes and Firmicutes compared with other phyla such as Proteobacteria, Tenericutes, and Verrucomicrobia in the LP group. There was a significant difference in microbial diversity within prevention and cure treatments. In summary, MCPPm weanimix could serve as a protective material to LP. Its performance in the mouse model indicates that it may potentially modulate the gastrointestinal microbiota in children experiencing diarrhea.

Date

5-23-2018

Committee Chair

Sathivel, Subramaniam

Available for download on Wednesday, May 21, 2025

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