Replication And Lifestyle Flashcards
Heterotrophic
Req organic substrates for e production and a wide substrate variety are used
Metabolism of most pathogenic bact
Take up and catabolise sugars
Peptides/aas
And nucleic acids to gen basic building blocks of anabolic process
Strict aerobes
Grow at atm O2 tensions
Strict anaerobes
Req O2 abscence for growth
Facuktative anaerobes
Can handle both presence and absence
Factors influencing bacterial griwth
Nutrients Temp pH Ion concs Atm Hydration
What may cause commensal bact pop alteration
Nutritional status Stress Age Antiobiotics (Pops are stable but not static)
Lag phase of growth
Bact adjust to enviro conditions
Log phase
Bact prolif exponentially by binary fission
Stationary phase
Nutrients become exhausted so growth arrest
Decline or death phasr
Bact number falls as incr hostility of enviro
What occurs during binary fission
A new CM and CW are formed
Chromosome duplicates and segregates
Septum spilts bact cell into 2 compartments
Separate into 2 cells
Growth phases
Lag
Log
Stationary
Decline/death
When sporulation Occurs
Stationary phase usually
In response to stress or nutrient limitation
Spore producing bacteria
Clostridium
Bacillus
What are spores
Dormant struct res to adverse cond of heat dehydration freezing and many chem that would kill most vegetative bact
Conditions to kill vegetative bact v spores
V: 50-70 degree C
S: most resist boiling but not autoclave (121 degree C 15min)
Changes during sporulation
Many components of vegetative cell disappear and thick wall formed to protect genetic material and transcription translation machinery
Spore germination
Under appropriate conditions
Can persist for 50+ yrs in poor enviro so source of infection fir long time periods
Septicaemia growth eg
Can have Rapid multiplication in blood and host resp to high bact product (LPS and peptidoglycan) level lead to septic shock and organ failure
Mycobacterium growth rate eg
Take long time to manifest, can be harder for host ti tackle
Other factors affecting growth rate
Site of infection
Niche specialisation IC eg
Diff IC bact use diff C source in infected cell, may alter cell metabolism in favour of these products
Niche specialisation skin eg
Can survive lower temp and can take advantage if sebaceous gland secretion (cont TG) or may degrade skin and pro with enz and proteases to give substrates for growth
Mech to obtain Fe if conc is low
EC hydrolytic enz
Transferrin and lactoferrin bind pros
Siderophores and spec recs
Niche specialisation GIT eg
Can kill related bact with colicins and bacteriophages (compete for nutrients)
Invasion
Community formation to BD complex substrates
Eg of niche bact
Mycobact leprae (schwann cell) E coli (end of bovine GIT) Salmonella (gall bladder persistance) Strep (horse guttyral pouch) Staph (bone joint infections)
Technique to ID bact not easily cultured
PCR amplification and immunodiagnostic tachniques (same as virus diagnostics)
