Abstract
Objectives
Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrhea in human infants and young farm animals. Osteopontin (OPN), a glycoprotein present in high concentration in human milk, has immunomodulatory functions, which could indirectly impact the microbiota. Furthermore, a previous study has shown fecal microbiota composition differs between wild-type and OPN knockout mice. Herein, the effects of OPN-enriched algae on the gut microbiota composition and volatile fatty acid (VFA) concentrations of ETEC-infected piglets were assessed.
Methods
Naturally-farrowed piglets were sow-reared for 21 days and then randomized to two weaning diets: WT (formula + 1% wild-type algae) or OPN (formula + 1% OPN-enriched algae). On postnatal day (PND) 31, all piglets were infected orally with a live culture of ETEC (1010 colony-forming unit/3 mL dose) daily for three consecutive days. On PND 41, ascending colon (AC) contents were collected. Gut microbiota was assessed by sequencing V3-V4 regions of 16S rRNA gene and VFAs were determined by gas chromatography. Alpha-diversity and VFAs were analyzed using PROC MIXED procedure of SAS. Beta-diversity was evaluated by permutational multivariate analysis of variance (PERMANOVA) and differential abundance analysis on the bacterial genera was performed using DESeq2 package of R.
Results
Shannon indices were lower in the AC contents of OPN piglets compared to WT piglets. The overall colonic microbiota of OPN piglets differed from that of WT piglets (PERMANOVA P = 0.015). At genus level, OPN-enriched algae increased the abundance of Streptococcus, decreased the abundances of Sutterella, Candidatus Soleaferrea, dga-11 gut group, Rikenellaceae RC9 gut group, Ruminococcaceae UCG-010, unculturedRuminococcaceae, Prevotella 2 and 7 compared to piglets consuming wild-type algae (P < 0. 05). OPN piglets also had higher (P < 0.05) concentrations of acetate, propionate, butyrate and valerate compared to WT.
Conclusions
In ETEC infected piglets, 1% OPN-enriched algae decreased alpha-diversity and modulated the microbiota composition and VFA profiles compared to 1% WT algae. Other studies have shown that OPN inhibits biofilm formation in vitro, but future research is needed to assess in vivo microbiome-modulation mechanisms.
Funding Sources
Triton Algae Innovations.
An Overview of the Elusive Passenger in the Gastrointestinal Tract of Cattle: The Shiga Toxin Producing Escherichia coli