Microbial fermentation Flashcards Preview

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Flashcards in Microbial fermentation Deck (25):
1

Fermentation is ...?

Anaerobic digestion of substrates by bacteria & other microorganisms

2

Fermentative digestion enzymes are ___ in origin

microbial

3

Difference between fermentative & glandular digestion

Fermentative = SLOWER

4

Requirements for proper fermentation?

Temp = 37 degrees
pH buffered
Osmolality optimum
Suitable substrate (CHO)
Indigestible material removed
Rate of removal = regeneration time of favourable microbes
VFAs removed or buffered

5

Major food sources for fermentation for large herbivores?

Forages/foliage of plants

6

Glue cellulose together?

Hemicellulose, lignin, pectin

7

CHO digestion involves which 3 plant CHOs?

Insoluble structural polysaccharides (cellulose, hemicellulose)
Soluble structural polysaccharides (gels - pectins)
Storage mono-, oligo-, polysaccharides (starch)

8

Function of the rumen?

Large, anaerobic fermentation vat
Soluble products mostly absorbed thru wall
Material leaving RR = food residues, bacteria, protozoa, (+soluble fermentation end products)

9

Fermentation microbes are mainly?

Fungi
Bacteria
Methanogens
Mycoplasms
Phages (viruses)
At least 28 important spp

10

A bit about fungi...?

Anaerobes
Survive completely on ingested feed
Able to digest cellulose, starch etc
1st organism to attack & start digesting structural plant components
Not numerous, but take 1st bite

11

A bit on rumen bacteria..?

Most are strict anaerobes
10^10 bacteria/g ingesta
Synthesis microbial protein
Wide range >200 spp.
Pop. needs time to adapt to change in diet

12

Rate of bacterial population depends on?

Available energy
Bacterial turnover time
Limited by cellulose digestion
Limited by starch storage by protozoa

13

Bacterial growth requires...?

Fermentable CHOs
N for protein synthesis (ie ammonia, AAs, urea or peptides)
Other micronutrients (sulphur)

14

Rumen bacteria & substrates are...? Give egs

Widely adapted (Lactobacilli/butyrivibrio)
Digest cellulose & hemicellulose (Ruminococcus)
Digest starch (streptococcus bovis)

15

Properties of methanogens...?

CH4 (methane) producing archea
Similar to bacteria
Produce methane as end product of feed in rumen

16

Example of methanogens?

Methanobrevibacter

17

Protozoa properties?

Much larger than bacteria
Fewer in number
Increase with [starch]
Feed on bacteria

18

Define defaunation

removal of protozoa -> increase bacteria -> increase bacterial protein-N -> decrease ruminal [NH3]

19

Most important protozoa?

Anaerobic ciliates

20

2 families of protozoa & apperance?

Holotrich - 'hairy' covered by cilia
Entodiniomorphid - 'tufted' most of body naked except tufts/patches of cilia

21

Holotrichs properties...?

Use starch & sugars
Associated with feed particles
Do not readily pass from rumen
Store sugars

22

Fermentation end products of holotrichs?

Acetic acid
Butyric acid
Lactic acid
H2 gas

23

Entodiniomorphs properties...?

10 genera
Ingest starch, plant material, bacteria
Digest cellulose/hemicellulose
Increase in no. when animal eats grain diet

24

Mycoplasms properties...?

Smallest bacteria
Cell membrane NOT cell wall
~10^6/g ruminal contents (sheep/cattle)
Important in maintaining balanced ecosystem
Provide energy for ruminants

25

Bacteriophages (viruses) properties...?

Can burst open other microbes
Lyse bacterial hosts
Involved in protein recycling
Possibly beneficial