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Chapter 25 : Strategies for Altering the Intestinal Microbiota of Animals
Category: Clinical Microbiology
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In this chapter the term probiotics is used in a broad sense to include the use of various different microbes in veterinary strategies aimed at manipulation or replacement of intestinal microbes. The reduction in the incidence of diarrhea by probiotics has frequently been studied because this problem is of the utmost importance for farm animals. Neonatal farmhouse animals including piglets often have an insufficiency of stomach acid, which is the first line of defense against bacterial invasion. Microbes of all types, including bacteria, viruses, archaea, fungi, and protozoans, colonize and persist in the intestinal tract of farm animals. Genomic analysis of differential gene expression in microbes and higher organisms has been greatly facilitated by the development of DNA microarrays. This technology has been exploited to monitor global intestinal transcriptional responses to the colonization of germ free mice with Bacteroides thetaiotaomicron, a prominent member of the normal murine and human intestinal microbiota. This study showed that this commensal was able to modulate expression of host genes participating in diverse and fundamental physiological functions, including nutrient absorption, mucosal barrier fortification, xenobiotic metabolism, angiogenesis, and postnatal intestinal maturation. Recent in vitro studies have suggested that probiotics can have protective effects on cytokine-induced apoptosis or permeability changes, attenuate epithelial inflammatory responses, and reduce invasion or adherence of pathogens.
Overview of beneficial effects of some microorganisms in different animal species