174 The effect of a microbial Muramidase on peptidoglycan content in the gut of swine using in-vitro and in-vivo measures

Abstract Bacterial debris in the gastrointestinal tract (GIT) are continuously being produced by the microbiota present upon bacterial division and death. One of the most abundant components in bacterial debris are peptidoglycans (PGN), a structural cell wall component in gram- positive and negative bacteria. The objective of this work was to investigate if addition of a novel microbial muramidase (Muramidase 007; MUR) that hydrolyzes PGN, would reduce PGN adhesion to porcine intestinal cells in-vitro and hydrolyze PGN in the GIT of swine. Adhesion efficacy of intact and MUR hydrolyzed fluorescein-isothiocyanate (FITC)-labelled PGN were compared using fluorescence-microscopy (3 wells/condition). Catalytic performance of MUR on intact FITC-labelled PGN adhered to intestinal cells were also tested. In-vivo MUR-supplementation at 50,000 LSU/kg diet to gestating and lactating sows and/or their subsequent offspring for 42-d post-weaning was investigated. Mass-spectroscopy was used to quantify soluble and total muramic acid, which is only found in PGN, in the ileal and cecal digesta (8 piglets/treatment) to calculate percentage soluble-PGN. Cell-culture data were analyzed using GraphPad-Prism 8.0 and in-vivo data using mixed-models in JMP 14.0. MUR hydrolyzed PGN adhered 10x less to the IPEC-J2 cell line culture compared to intact-PGN (P< 0.05). In addition, data show that MUR hydrolyzed PGN attached to cell surfaces by 2x, as attached PGN were also reduced by 50% following MUR incubation (P< 0.05). Offering sows MUR-diets had no carryover effect on the percentage soluble PGN in their piglets’ digesta, and there were no interactions observed for sow x piglet x tract neither (P >0.05). Percentage soluble-PGN increased in piglets fed MUR compared to control-piglets (47.18 vs. 29.84% SEM:1.624; P< 0.001) and was higher in cecal digesta compared to ileal digesta (49.91 vs. 27.11%; SEM:1.634; P< 0.001), irrespective of MUR-supplementation. These results suggest that MUR may reduce PGN adhesion to intestinal cells and may hydrolyze PGN found in the GIT.