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The importance of Gut microbes (Rumen microbes display specialisation for…
The importance of Gut microbes
Rumen - Large and complex populations of micro-organisms, essential for energy and protein requirements. Community must be in balance to ensure health.
The eating and rumination patterns vary among species according to the feeding habit and on the type of nutrients from the plants on which they rely - this will affect microbial population.
Rumen microbes display specialisation for specific substrates.
Structural carbohydrate fermenters
- Cellulose, hemicelulose. Some will digest starch and proteins
Pectinolytic species
focused on pectin but some may also digest cellulose and hemicelullose
Non-Structural carbohydrate fermenters
- starch and sugars with some also being able to digest other substrates (wide mix)
Lipolytic species
- Sugars, lipids, protein and acids
Proteolytic species
- Proteins and sugars
Multiple group of bacteria in the Rumen
Free-living in the liquid phase, Loosely associated with feed particles, firmly adhered to feed particles, associated with rumen epithelium and attached to surface of protozoa and fungi.
Fibre digestion
Commonly considered the rumens primary functions, many of the rumens organisms degrade cellulose faculatively, they also require B vitamins, ammonia, CO2 and organic acids to grown
Example = Ruminococcus albus
Protein breakdown
Protein breakdown is carried out by proteolytic species
Most dietary protein is broken down into ammonia which is required by some primary fermenters. Some ammonia gets incorporated into bacterial cell walls - major source of protein for the host
Pectinolytic species
Pectin is a starch found naturally in varying quantities in organic matter. Grasses contain 3 to 4% pectin. They are fermented to glucose in the rumen
Lipolytic Species
Lipids are a byproduct of the fermentation of structural carbohydrates and in the form of VFAs are an important source of nutrients for the ruminant
Fatty acids get converted from polyunsaturated fatty acids to saturated fatty adics in a process called biohydrogenation
Hydrogen utilisers
Methanogens - utilise Co2 and hydrogen in their metabolism and produce methane as a by product
Only constitutes about 5% of all the microbes in the rumen but soley responsible for all methane production in the rumen
Forms close relationships with other organisms that produce hydrogen
Rumen protozoa
Entodinomorphids- engulf large pieces of plant for internal digestion
Holotrichs - Produce exocellular enzymes which release soluble sugars which are then absorbed
Protozoa may actually have negative effects- causing 80% of protein breakdown - defaunation increases microbial protein flow
Rumen Fungi
Zoospores quickly attach to feed material and actively degrade plant cell walls. They are better able to colonise and degrade lignin-containing tissues than bacteria. The only microbe that can penetrate the plant cuticle
Bacteriophages
Interest in the use of using rumen phages to control the microbiome for example redcuing the methanogen population to reduce methane emissions