Microbial fermentation Flashcards
Fermentation is …?
Anaerobic digestion of substrates by bacteria & other microorganisms
Fermentative digestion enzymes are ___ in origin
microbial
Difference between fermentative & glandular digestion
Fermentative = SLOWER
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
Major food sources for fermentation for large herbivores?
Forages/foliage of plants
Glue cellulose together?
Hemicellulose, lignin, pectin
CHO digestion involves which 3 plant CHOs?
Insoluble structural polysaccharides (cellulose, hemicellulose)
Soluble structural polysaccharides (gels - pectins)
Storage mono-, oligo-, polysaccharides (starch)
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)
Fermentation microbes are mainly?
Fungi Bacteria Methanogens Mycoplasms Phages (viruses) At least 28 important spp
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
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
Rate of bacterial population depends on?
Available energy
Bacterial turnover time
Limited by cellulose digestion
Limited by starch storage by protozoa
Bacterial growth requires…?
Fermentable CHOs
N for protein synthesis (ie ammonia, AAs, urea or peptides)
Other micronutrients (sulphur)
Rumen bacteria & substrates are…? Give egs
Widely adapted (Lactobacilli/butyrivibrio) Digest cellulose & hemicellulose (Ruminococcus) Digest starch (streptococcus bovis)
Properties of methanogens…?
CH4 (methane) producing archea
Similar to bacteria
Produce methane as end product of feed in rumen
Example of methanogens?
Methanobrevibacter
Protozoa properties?
Much larger than bacteria
Fewer in number
Increase with [starch]
Feed on bacteria
Define defaunation
removal of protozoa -> increase bacteria -> increase bacterial protein-N -> decrease ruminal [NH3]
Most important protozoa?
Anaerobic ciliates
2 families of protozoa & apperance?
Holotrich - ‘hairy’ covered by cilia
Entodiniomorphid - ‘tufted’ most of body naked except tufts/patches of cilia
Holotrichs properties…?
Use starch & sugars
Associated with feed particles
Do not readily pass from rumen
Store sugars
Fermentation end products of holotrichs?
Acetic acid
Butyric acid
Lactic acid
H2 gas
Entodiniomorphs properties…?
10 genera
Ingest starch, plant material, bacteria
Digest cellulose/hemicellulose
Increase in no. when animal eats grain diet
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
Bacteriophages (viruses) properties…?
Can burst open other microbes
Lyse bacterial hosts
Involved in protein recycling
Possibly beneficial
