NUT 141 Lecture 2 Gut microbiology & fermentation

microbes in ruminants importance

ferment fiber to VFA + lactate (75% of energy metabolized by host)

pass to s intestine to be digested (cells protein rich & make up 50% of protein metabolized by host)

microbes in ruminants major groups

bacteria

protozoa

fungi

methanogens

viruses

bacteria in ruminant

90% of microbial mass

small 0.3 to 50 μm

ferment fiber (cellulose, hemicellulose, pectin), starch, sugar, protein, aa (bad since host can digest protein), lactate

ciliate protozoa in ruminant

3-50% of microbial mass

large 20 to 200 μm

ferment many things

predators of bacteria & other microbes

predation of bacteria by protozoa

supplies protozoa w/ protein, nucleic acids & other things for growth

decrease flow of microbial protein to small intestine

flagellate protozoa in ruminant

not abundant

not cultured in last 60 years so unknown

belong to eukaryota

fungi in ruminant

0.5-8% microbial mass

moderate size 10 μm

>10 species

complex life cycle

ferment fiber (thallus penetrates deeply into cell wall and break them)

belong to eukaryota

life cycle of fungi

fungi begins as zoospores (free swimming)

zoospores attach & burrow into cell walls

thallus develops in cell wall (sporangium & rhizoids)

mature sporangium erupts & releases new zoospores

sporangium

oval structure containing future zoospores

part of thallus which is immotile

releases zoospores

rhizoids

root like structure that anchor the thallus into cell wall

part of thallus

methanogens in ruminant

0.5-3% microbial mass

small 0.8 to 2 μm

produce methane

belong to archaea

viruses in ruminant

bacteriophages (infect bacteria)

very small <1 μm

microbes of horses

grow in cecum & colon

ferment fiber (VFA + lactate) to make up 30% of energy

also in stomach (upper part is non-glandular; ferment start to lactate which cause laminitis - lameness)

groups in stomach of horse

bacteria

groups in caecum/colon

bacteria (most)

methanogens

fungi & protozoa (equal, least)

viruses not reportedre

fermentation in horses

stomach is to lactate

cecum & colon to VFA (acetate, propionate, butyrate)

all animals have gut microbiome

caterpillars are the exception

fiber to VFA energy in animals

ruminant 30-80%

human 6-9%

cecum 6-38%

caecum-colonic & colonic 30%

importance of microbes in other animals

pass to small intestine & digested if:

microbes upstream of small stomach (if microbes in stomach)

copography

microbes in all animals

bacteria

methanogens

viruses