Microbial growth 2 Flashcards
Growth associated
form simultaneously during microbial growth e.g ethanol
Non-growth associated
Takes place during stationary phase at a constant rate e.g penicillin
Mixed-growth associated
Takes place during slow growth and stationary phase e.g lactic acid
Balanced growth
microbial growth unconstrained by nutrient limitation. Typically associated with the exponential growth phase`
Catabolic by-product
Stuck fermentations, anaerobic fermentations produce organic acids and alcohol by-products. At high concentrations they cause cellular metabolism to shut down
Toxic chemical waste
Cyanide and phenols can be used at catabolic nutrients, but at high concentrations they react with cellular proteins to stop cell growth
Antibiotic resistance
Steals energy (ATP) from growth , efflux pump
Unbalanced growth
unbalanced growth conditions promotes sequestering of resources and the synthesis of intracellular energy reservoirs.
Unbalanced growth cause
occurs when one or more nutrient may be limiting (C,N,O,P) and can result in changes to concentration of various intracellular components.
stationary phase
no growth, but cells are still metabolically active (consume substrate)
cell survival strategies
Changes to cell morphology
• consumption of intracellular energy reservoirs (e.g. glycogen,
PHA)
• expression of scavenging enzymes (e.g. alkaline phosphatase, trace gas consumption (H2, CO))
• sporulation
Death phase
rate of cell growth is less than the rate of cell death so a net decline in cell viability is observed. Occurs at a constant exponential rate
Cell death causes
- entropic decay (energy starvation.
- starved for P,N,S
Sterilization
Destruction or removal of all forms of microbial life +endospores
Disinfection
Destruction of vegetative pathogens
