The Rumen Gut Microbe for Life

Introduction

Ruminants diet is rich in fiber (consists of polymers e.g. cellulose) and low in proteins. Almost all animals as well as mammals lack the enzymes for metabolizing cellulose. Only microorganisms possess such enzymes which aid in fermenting cellulose and other polysaccharides consumed by the ruminants.

The microorganisms are in a symbiotic relationship with the host.

Rumen habitat

Rumen, a special digestive organ that harbor billions of microorganisms including bacteria, protozoa, and fungi which exist together. Such habitat has some certain conditions that favors the stay of these microbes.

Rumen anatomy

Characteristics of rumen that maintain microorganisms are:

A capacious rumen

Anaerobic fermenter

Warm and constant temperature (39℃)

Narrow pH range (5.5 to 7.0 depends on diet and saliva production)

Digestive system of the ruminants consists 4 compartments:

Rumen

Reticulum

Omasum

Abomasum

Digestive mechanism- food first passes from esophagus to the reticulum and rumen then to omasum and lastly to acidic abomasum. Among these compartments rumen is considered the main fermenter tank which holds microorganisms

Rumen microbiota

The microorganisms are in a symbiotic relationship in the anoxic rumen.

Microbiota is composed of bacteria, protozoa, and fungi, at concentrations of 1010, 106, and 104 cells/ml, respectively. It is evident that bacterial population is most abundant, and any physicochemical changes are vulnerable to them.

Ruminal bacteria

Rumen contains a diversified bacterial general

As ruminants are herbivorous cellulose is one of the main component of their diet, so the need of degrading cellulose is paramount. Thus, the presence of cellulose degrading bacteria such as Fibrobacter succinogenes, Butyrivibrio fibrisolvens help to break the β 1,4 glycosidic bonds of cellulose providing nutrition to the host.

The ruminant gut also contains amylolytic bacteria such as S. bovis that helps to break starch component of the host diet. In addition, the rumen also contains important degrading bacteria like dose in the form of lactate degrading bacteria, pectin degrading bacteria etc.

The total ruminal bacteria help to produce volatile fatty acids which are fermentation products that helps to maintain the biochemical pathways that are present in its gut.

These abundant bacteria are digested in the acidic abomasum providing vital protein and vitamins to the host.

The abundance of the ruminant bacteria depends on the diet that the ruminant is on.

Ingested forage proteins and polysaccharides are degraded by proteolytic bacteria- Bacteroides amylophilus, Bacteroides rutminicola, and Butyrivibrio fibrisolvens

Lipids are converted into saturated fatty acid in rumen by lipolytic bacteria. Examples- Megasphaera elsdenii, B. fibrisolvens.

Other than ruminal bacteria there is presence of archaea or methanogens. Carbon dioxide and hydrogen formed during fermentation is converted to methane by the methanogens such as methanomicrobium mobile, methanobrevibacter ruminantium also these microorganisms can degrade substrates containing methyl (CH3-) or acetyl (CH3OO-) groups, such as methanol and acetate.

Besides the prokaryotes there are existence of protozoa and fungi (table 2). Both playing roles in metabolism of the ingested food.

Consequences

All the microorganism in the rumen are interdependent on other. The product of one’s fermentation is metabolized by other. The composition or the proportion of these microbes depend on the diet of the ruminant. For example, if a ruminant is feed with food rich in pectin from the earlier cellulose rich food the pectin degrading Bactria will now dominate over the cellulose degrading microbes such abrupt changes may causes illness or even result in death.

One of the health consequence is acidosis occur when there is excess production of lactic acid this happens when sudden change in diet from forage to grain.

Conclusion

In a nutshell, it is modestly comprehensible that the rumen gut has got a complexly integrated microbial community that is of great significance to both, the survivability of those ruminant microbial gut and that of the ruminant digestion. This is due to the fact that the microbial community is performing ruminal fermentation that has a superiority on the ruminant’s nutrition. Thus forms a interdependency between the host and the microbe. However, the modern diet that the rumens are subjected to, tends to jeopardize the survivability of the ruminant gut flora with adverse consequences. To prevent such menacing repercussions, molecular techniques have come into assistance to keep the mutualistic relationship intact by enhancing our knowledge and understanding on the symbiotic relationship that exists among them and the addition of additives that inflates nutrition usage and simultaneously reduces the accumulation of environmentally harmful products. Thus, providing a win-win situation for both the microbes and the rumen.