Ruminant 2 Flashcards by Jessica Swanson

What is an example of true symbiosis?

Between the ruminant and its rumen microbes

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How does symbiosis work in the ruminant?

-microbes of the rumen depend on the ruminant essential conditions
-ruminant provides habitat and microbes provide end products of fermentation

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What are microbes essential for?

-Digestion and fermentation of fibrous feedstuffs that could not otherwise be used for nutrients.

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What are some characteristics of the rumen?

-low oxygen environment
-very fluid: facilitates microbial interactions and enzymes with feed
-open and continuous ecosystem maintaining a stable microbial population
-carbohydrate rich
-a little is going to come out at a time

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What gases are in the rumen?

-65% CO2, 7% N2, and 0.6% O2 in the rumen

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What is the dry matter content in the rumen?

-varies from 6-18% depending on area in the rumen

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Do fractalated or obliques like oxygen?

-Fractalated use oxygen
-Oblique don’t like oxygen

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What type of environment favors lack of oxygen?

-lack of oxygen favors anaerobic microbes

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What is the rumen support by?

-a constant supply of substrates (eating food) and a large holding capacity
-capacity aids in retention of complex diet components allowing degradation and fermentation

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Since the rumen is carbohydrate rich what makes up most of the feed?

-cellulose and other polysaccharides

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Are small or large particles retained until sufficient degradation has occurred?

-Large

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What is the rate of passage (Kp)

-amount of liquid and particulates that flow out of the rumen per unit time
-typically expressed as a percentage 8%/h

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What type of microbe diversity is in the rumen?

-Bacteria
-Protozoa
-Fungi

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Characteristics of rumen bacteria

-digestion and fermentation of feed
-10^10 -10^11 / mL bacteria
-0.3-50 um

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Characteristics of rumen protoza

-slow rate of pH decline
-majority are ciliated, but some flagellates
-contribute to fermentation
-predators of bacteria

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What is rumen protozoa estimated to be comprised of?

-40% of microbial N
-60% of fermentation products

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How does rumen protozoa contribute to fermentation?

-starch
-sugars
-pectin
-hemicellulose

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Why are rumen protozoa predators of bacteria?

bacteria consumed for protein

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Characteristics of rumen Fungi

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-attachment site for bacteria
-10^2 - 10^4 / mL fungal zoospores

Classification of rumen bacteria by substrate:
cellulolytic, Hemicellulolytic and Pectinolytic, Amylolytic, Proteolytic, Ammonia producing, Lipolytic, Intermediate acid utilizers, and Simple sugar users

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-cellulolytic = cellulose
-Hemicellulolytic and Pectinolytic = hemicellulose and pectin
-Amylolytic = starch
-Proteolytic = proteins
-Ammonia producing = amino acid deaminators
-Lipolytic = lipase producers
-Intermediate acid utilizers = lactate, succinate, formate
-Simple sugar users

Characteristics of anaerobic fungi

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-attach to and found within plant fragments
-contribute to the degradation of cellulose and other polysaccharides

What makes up microbial interdependence?

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-Intermediate cross feeding
-VFA requirements
-Interspecies hydrogen transfer

What is intermediate cross feeding?

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-Intermediates being metabolites produced through cell processes
-sharing of intermediates between species
-end products of one become the substrate of another

Explain how B. succinogenes and S. ruminantium is an examples of intermediate cross feeding?

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-Selenomonas ruminantium cannot use cellulose, but Bacteroides succinogenes does
-B. succinogenes produces succinate and S. ruminantium can use the produce succinate

Explain how lactate and Megashaera is an examples of intermediate cross feeding?

-lactate production, sometimes associated with starch feeding, can be used by Megashaera elsdenii to produce propionate

What can rumen bacteria not use?

-cellulose

What are VFA requirements in microbial interdependence?

-Sharing some VFA among non-cellulolytic and cellulolytic bacteria -production of branched chain VFA like n-valeric or 2-methbutyric acids from deamination of branched chain amino acids by non-cellulolytic bacteria -provides carbon skeletons

What does providing carbon skeletons do?

-for synthesis of amino acids -also for synthesis of microbial fatty acids with branched or odd numbered chains -found in the cell membranes of bacteria

What is interspecies hydrogen transfer relating to microbial interdependence?

-in the rumen there are H2 producing and H2 utilizing species -much of the H2 is used to produce methane (CH4) from CO2 -Transfer of H2 to methane producers encourages more H2 production -H2 producing pathways are associated with greater energy production

What does higher ATP yield by bacteria support?

-more bacterial growth -more microbial protein production

What are the substrates of fermentation?

-Not lipids: hydrolyzed to free fatty acids and glycerol backbones, but not fermented in appreciable quantities -some protein/amino acids utilization -carbohydrates: structural and non-structural

Characteristics of carbohydrate substrates of fermentation

-several sugars are found in hemicellulose -sugars: in feed or produced by polysaccharides hydrolysis -starch -pectin: early structural polysaccharides of developing plant cell walls

How does variable fermentation rates work?

-soluble CHO fermented first: sugars, some starch -pectin next -structural CHO, cellulose last -easier to attack or hydrolyze substrates earlier and faster than harder to attack substrates

What does fermentation always follow?

Hydrolysis

What is pyruvate converted through a pathway?

VFA

What occurs in acetate production?

-pyruvate is first converted to acetyl-CoA -Acetyl-CoA can then be converted to acetate propionate production

What are the three main pathways for propionate production?

-succinate pathway -acrylate pathway -propanediol pathway

What occurs on the butyrate production?

-butyrate is typically produced from butyryl-CoA which is derived from two molecules of acetyl-CoA

Examples of short chain fatty acids

-butyrate -propionate -acetate

What does 2 hexose produce?

-2 butyrate -4 H2 -4 CO2

What does 3 hexose produce?

-4 propionate -2 acetate 2 CO2 -2 H2O

What does Hexose + 2 H2O produce?

-2 acetate -4 H2 -2 CO2

What is the molar ratio?

-acetate: propionate: butyrate -70:20:10 (60:30:8)

What does hydrogen and carbon dioxide production do?

-Hydrogen inhibits higher energy yielding pathways (hydrogen transfer)

What does hexose produce from methane?

-2 acetate -CO2 -CH4

What does acetate from CO2 produce? (4 H2 +2 CO2)

-1 acetate -2 H2O

What does hexose from acetate from CO2 produce?

3 acetate

Ruminant 2 Flashcards

(47 cards)