Resistance of endospores Flashcards
Mineralization of protoplast
-Calcium and magnese
-Dipicolinic acid (20% of core dry weight)
-water and intercalation
Ca, Magnese and Dip effect
-Bind to water and intercalates DNA to stabilise it which prevents damage to DNA via heat or dessication, especially dry heat
Dehydration of spore protoplast
Process driven by cortex and occurs via osmosis
-Reducing core water will increase wet and dry heat resistance
SASPs
small acid soluble proteins
-Make up to 10% of spore core protein
-Bind to DNA and saturate it (especially alpha and beta type), provides protection against wet heat and radiation
spore coat
-protective enzymes: catalase and superoxide dismutase inactivate toxic chemicals
-Reactive armour: Detoxify damaging chemicals before they reach core
-Block lytic enzymes: Prevents lyases from reaching PG layers
Inner membrane
-low permeability: slows entry of molecules and provides restriction against chemicals
-during germination, it has similar permeability to growing cell
Resistance mechanisms
-Minerilisation
-Dehydration
-SASPs
-Spore coat
-Inner membrane
Transformation to vegetative cell
Can survive millions of years in hibernation state
-Activation
-Germination
-Outgrowth
ACtivation
-Process is reversible
-Activation triggers:
aa, carbohydrates, Heat (comp is killed)
Activation trigger for subtilis
l-alanine
Germination
-1-1.5hr
-Irreversible: degredation of SASPs by endoproteases which serve as a source of metabolites and precursor for protein synthesis
-Cortex PG degraded by cortex lytic enzymes which allows H2O to enter cell core
-Germ cell wall becomes cell wall
-DNA repair enzymes activated
-Spore coat enzymes use 3-Phosphoglyciric acid from core to make ATP
Outgrowth
Remnants of endospore remain while vegetative cell moves out
