Electron-Microscopic Investigation of the Flora of Sheep Alimentary Tract

Abstract

SummaryDigesta from different regions of the sheep alimentary tract have been examined using electron microscopy. Direct examination of digesta from the rumen has revealed the presence of a number of phages and of a large variety of bacteria differing considerably in their morphology. An atlas of electron micrographs of these bacteria has been presented. The presence of large numbers of bacterial cell walls ;n the rumen indicates that the breakdown of bacteria commences in this organ. The major sites of digestion of bacteria are in the abomasum and small intestine where there is a substantial removal and modification of bacteria. INTRODUOTIONBacteria appear to undergo lysis in the rumen of sheep as indicated by the presence of large numbers of cell walls in any sample examined (Hoogenraad et al. 1967). Some of the factors responsible for such lysis have been indicated by Jarvis (1968). In addition it has been shown that rumen bacteria, and their cell walls, are susceptible to degradation under conditions similar to those existing in the alimentary tract of sheep and are digested during their passage through it .The present paper arose out of an attempt to follow such digestive processes by examining morphological changes in rumen bacteria as they pass along the alimentary tract. As an initial step, a detailed study of bacteria from rumen contents of sheep was undertaken using the electron microscope.In the studies of Moir and Masson (1952) by visual light microscopy, and of Smiles and Dobson (1955) by ultraviolet microscopy, many of the larger organisms found in the rumen were described. Several electron micrographs of rumen bacteria have also been published by Hungate (1966). However, most of the smaller organisms which form the bulk of the rumen population have not been described. Accordingly, we present electron micrographs of bacteria taken directly from rumen contents. Smiles and Dobson (1955) examined samples from rumen, omasum, and abomasum of sheep using ultraviolet microscopy and found that degenerative changes of various bacteria occur in the omasum and particularly the abomasum. To extend this study, samples from the rumen, omasum, abomasum, and different regions of the small intestine were inspected with the electron microscope to see whether degenerative changes also occur with the smaller bacteria. Parallel to this study, total bacterial counts were made by light microscopy.

The bacteriophages in human- and animal body-associated microbial communities

“…Several other phages of similar but not identical morphology were also observed. Phages with very long tails were also described in ruminal samples (Hoogenraad and Hird 1970; Tarakanov 1971a; Klieve and Bauchop 1988). This morphological feature can confer a particular adaptive advantage in the highly viscous environments of the rumen or gut, allowing the phage to scan for host receptors large volumes of liquid around the capsid, benefiting from rotational movement of the particle.…”

Ecological Basis for Rational Phage Therapy

“…The quantity and variety of phages in animal microflora. the bulk of articles on this subject study bacteriophages inhabiting the digestive tract of mammals (see further), including the colon (and feces), the rumen (for ruminants) and forestomac (for marsupials) microflora [14], where phages are the most abundant free viral particles [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Interestingly, most of the rnA-bearing viruses in human feces are plant viruses particles, which are ingested with food [27].…”