week 11 Flashcards
bottling process
preserve food by holding it at high temperatures and pressures for 10-15 minutes to kill microorganisms
Clostridium botulinum is a gram……soil bacterium
positive
Clostridium botulinum produces…….which blocks the release of neurotransmitters
botulinum toxin
botulinum toxin causes…….
flaccid paralysis
endospores
highly-resistant structures formed during harsh environmental conditions
3 parts of endospores
core
cortex
coat
core of an endospore
DNA, proteins
cortex of endospore
thick cell-wall layer to protect the core
coat of endospore
rigid protein structure to protect cortex and core from environmental damage
endospore formation sequence
- DNA replicates (septum forms at one cell end)
- membranes from around the DNA
- forespore forms additional membranes
- protective cortex forms around the spore
- protein coat forms around the cortex
- spore is released
3 mechanisms spores protect DNA
- small acid-soluble proteins in the core saturate the DNA and protect it from heat, drying, chemicals, radiation
- dehydration contributes to heat and radiation resistance
- DNA repair enzymes are present in the core, which help repair any DNA damage during germination
endospore germination 3 stages
Activation
-Endospore receptors detect nutrients available in the medium
Initiation
-Activated endospore receptors trigger autolysins to degrade the cortex peptidoglycan.
-Water is absorbed and the spore cortex and coat are degraded by hydrolytic enzymes.
Outgrowth
-DNA, RNA, and proteins are synthesized
-a new germ cell emerges, breaking the spore coat and becomes a vegetative cell
Preventing food spoilage requires us to prevent microbial growth using………
Shelford’s Law of Tolerance
intrinsic factors
water availability
osmolarity
nutrient content
pH and buffering capacity
antimicrobial constituents
biological structures (rinds/shells)
extrinsic factors
temperature
humidity
presence and concentration of gasses
