In this ppt Rumen Ecology is discussed.

1. MICROBIOLOGY OF THE RUMEN
Microorganisms are found throughout the gut, from mouth to the anus. Wherever suitable
conditions and substrates occurs. They may be found attached to the epithelial surface, deep
in the crypts in the mucosa, or free in the gut lumen.
The rumen provides an environment which is very favourable for microbial growth. The pH of
rumen is normally between 5.5 and 7.0 and the temperature is about 39oC which is near
optimum for many microbial enzyme systems. Substrates is provided in a continuous manner.
Contraction of the stomach helps to bring the microorganisms into contact with freshly
ingested or ruminated feed and the fluid conditions are ideal for many microorganisms
.
Rumen microorganisms consists of bacteria, ciliated protozoa, fungi, and bacteriophages
(viruses).

2. Rumen Bacteria
Rumen bacteria are small cocci and rods like structures. Most classification
schemes of rumen bacteria are based on the type of substrates used as
primary source of energy.

3. A. Cellulolytic Bacteria (Cellulose fermenting)
Widely found in nature. Cellulose constitutes perhaps 70% of all organic carbon
in the biosphere. These bacteria produce cellulase, an enzymes which hydrolyse
β1-4 glycosidic bonds of cellulose, and of the dimer cellobiose. As we know that
no animal produces it own cellulase. Thus any animal which digests cellulose
must rely upon bacteria somewhere in its gut to hydrolyse the β1-4 bonds
between the glucose residues.
Cellulolytic bacteria are found in the highest concentration in the rumen of
animals consuming fibrous diets.
Important cellulolytic species include: Bacteroides succinogenes, Ruminococcus
flavefaciens, Ruminococcus albus and Cillobacterium cellulosolvens.

4. B. Hemicellulose Fermenting Bacteria
Hemicellulose differs from cellulose in containing pentose as well as hexose
sugars and usually uronic acids. Hemicellulose is an important structural
polysaccharide in plant cell walls and organism capable of hydrolyzing cellulose
are usually able to utilize hemicellulose.
Some species which ferment hemicellulose are: Butyrivibrio fibriosolvens and
Bacteroides ruminicola.

5. C. Amylolytic (starch fermenting) bacteria.
A number of cellulolytic organisms can also ferment starch, however,
amylolytic species cannot ferment cellulose.
Amylolytic species are found in greatest numbers when the animal is eating a
diet high in starch such as grains.
Important amylolytic bacteria include: Bacteroides amylophilus, Butyrivibrio
fibriosolvens, Bacteroides ruminicola and streptococcus bovis.

6. D. Sugar Fermenter Bacteria
Most of the bacteria which utilize polysaccharides are also capable of utilizing
disaccharides and monosaccharides. Young plant material contains
considerably readily fermentable carbohydrates which are rapidly fermented
as soon as ingested feed enters the reticulo-rumen. This is one disadvantage
of the ruminant system. It would be more efficient for the sugars to be
digested and absorbed directly by the host animal in the small intestine.
However, it is a small price to pay for the advantage of being able to utilize
polysaccharides as an energy source, for which the host is dependent on the
rumen microbiota.

7. E. Acid Utilizers Bacteria.
A number of rumen microorganisms utilize lactic acid, although it is not
normally present in appreciable amount. Others utilize succinic, malic or
fumaric acids produced as end products by other bacterial species. Formic acid
and acetic acid are also used by some species, although probably not as a
primary energy source. Oxalic acid, which is toxic to mammals, is also
decomposed by rumen microorganisms. This function of the rumen microbiota
enables ruminants to exploit plant materials which would otherwise be
poisonous and therefore not utilize. Some bacterial species which utilize lactic
acid, which may occur in high concentration if the animal has sudden access to
grains or other high-starch food.
Some species of acid utilizers bacteria include: Peptostreptococcus elsdenii,
Propioni bacterium and Selenomonas lactilytica.

8. F. Proteolytic Bacteria
These are the most widespread of bacteria in the gut of mammals, including
carnivores. In the rumen several species are known to utilize amino acids as a
primary energy source. These includes: Bacteroides amylophilus, Clostridium
sporogenes and Bacillus licheniformis.

9. G. Methanogenic Bacteria
About 25% of the gas produces in the rumen is methane. Methane producing
bacteria are slow-growing. Methanogenic bacteria species includes:
Methanobacterium ruminantium and Methanobacterium formicicum.

10. H. Lipolytic Bacteria
Some rumen bacterial species utilize glycerol, and only a few sugars. Others
hydrogenate unsaturated fatty acids and some apparently metabolize long-
chain fatty acids to ketones.

11. I. Ureolytic Bacteria
A large numbers of rumen bacterial species exhibit Ureolytic activity,
hydrolyzing urea to CO2 and ammonia. Many of these species are found
attached to the rumen epithelium and hydrolyse urea diffusing from the blood
into the rumen across the rumen wall. Thus, the concentration of urea in
ruminal fluid is always very low.
The usual range of bacterial numbers in the rumen is 15 to 80 × 109 per ml
contents. However, numbers may be as low as 4 × 109 per ml in animals fed on
wheat straw and as high as 88 × 109 per ml in sheep on good pasture.