12- Animal Microbiology

Question 1

Commensals

Answer 1

microorganism routinely found in healthy individual

Do not cause infection

Question 2

Animals as microbial habitats

Answer 2

Exposure: from the environment, other animals, food, and water.
Animal bodies provide:
- heat
- water
- nutrition for adapted bacteria

Question 3

Factors influencing animal microbiomes

Answer 3

temperature 
pH
nutrient supply 
immune system (genetic factor
and others 
as animals develop their microbiomes develop with them

Question 4

Commensals

Answer 4

use the host for nutrients and shelter without causing harm

may be beneficial or become parasitic

Question 5

beneficial commensals

Answer 5

Provide the host :

• with vitamins and metabolic pathways
• protection from incoming microorganism
• immune system practice

Question 6

parasitic commensals

Answer 6

commensal may become parasitic under specific conditions.

Commensals of one species may be pathogens to another

Question 7

Pathogens

Answer 7

microbial parasites what are able to cause infection

Question 8

Infection

Answer 8

situation in which a microorganism is established and growing in a host, causing damage

Question 9

Disease

Answer 9

damage or injury to the host that impairs host function

infectious disease, autoimmune disease, cancer, ect

Question 10

Pathogenicity

Answer 10

the ability of a parasite to inflict damage to the host

Question 11

Virulence

Answer 11

measure of pathogenicity

Question 12

Opportunistic pathogen

Answer 12

causes disease only in the absence of normal host resistance.
contained within the normal microbiome

Question 13

Gastrointestinal tract of animals

Answer 13

contain the vast majority of the microbiome

Question 14

Cellulose

Answer 14

insoluble polysaccharide

cannot be directly digested by animal due to las of cellulase

Question 15

Cellulase

Answer 15

enzyme which degrades cellulose

Question 16

Herbivores diet

Answer 16

rich in cellulose, lignin, hemicellulose, pectin and other insoluble polysaccharides
-> digested by microorganism in the GI tract (mutualism/symbiotic relationship)

Question 17

Digestive strategies: Cellulose

Answer 17

Foregut fermentation: fermentation chamber proceeds the acidic stomach
Hindgut fermentation: uses cecum and/or large intestine as fermentation chambers

Question 18

the Rumen

Answer 18

Present in ruminant animals
a.k.a. the foregut fermentation chamber
Food is minimally chewed, swallowed -> rumen
- ranges in capacity
-39-40C
- pH: 5-7 maintained by saliva containing sodium bicarbonate and sodium phosphate
- ANAEROBIC

Question 19

Rumen microorganisms

Answer 19

only a small proportion are cellulase producing

Fermentation is regulated by cellulolytic microbes

Question 20

Cellulolytic microbes

Answer 20

hydrolyze cellulose -to-> free glucose and cellobiose
products are now available for other microorganism growth
sugars are then fermented -> volatile fatty acids, CH4 and CO2
Fatty acids : pass through the rumen wall into the blood stream as main energy source

Question 21

Methanogens

Answer 21

strict anaerobes
produce CH4
4H2+CO2->CH4+2H2O + Energy
CH3COOH (acetate)->CH4+CO2+Energy

acetate is not avialable to the host: 10% of feed is lost energy

Question 22

Monensin

Answer 22

inhibits methanogenesis

added to fee to reduce CH4 production

Question 23

Rumens and regurgitation

Answer 23

after a few hours small portions of the rumen contents are regurgitated, chewed, and swallowed
smaller food particles are collected in the reticulum -then-to-> the omasum

Question 24

Omasum

Answer 24

recieves contents of the rumen afte rthe reticulum
collects ecess water
moves next to the abomasum

Question 25

Abomasum

Answer 25

a.k.a. stomach
the mass of microbial calls which gigested cellulose are now in term digested : major source of amino acids and vitamins
contents now move to the intestine

Question 26

Non-ruminent animals

Answer 26

Fermentation of cellulose : in the caecum
the microbial mass that grows on cellulose is not digested: it is excreted
Higher dietary requirement for amino acids and vitamins

Question 27

Caecum

Answer 27

provides organic acids to the animal

location of cellulose fermentation in non-ruminent animals