Bacterial Growth Metabolism Visser Flashcards
How is bacterial growth Measured ?
Direct Counting
- Microscopy
- Total Numbers
Colony Forming Units
- Serial dilution and plate on agar media
- Viable cell count
Turbidity
- Measure Light absorption
Bacteria require Macronutrients and Micronutrients
Macronutrients
- Large amounts
- Nitrogen, hydrogen, carbon, ect.
- Structural or functional role in cells
Micronutrients
- Trace amounts
- Zinc, Cobalt, Molybdenum
- Used as cofactors in enzymatic reactions
Prototroph
bacteria derives all nutrient requirements from sources contained in a mixture of macronutrients and micronutrients
(E. coli)
Fastidious Bacteria
have complex and specialized nutrient requirement (obligate pathogens)
- Ex need vitamins and A.A’s
(Mycobacterium Tuberculosis and Staphylococcus Aureus)
Most identified bacteria grow on artificial media
5% identified and cultured
Obligate pathogens cannot be (or easily grown) in culture
Treponema pallidum requires growth in mammalian hosts
Some bacteria have to be cultured intracellularly
Rickettsia(R.typhi (typhus), R.Rickettsii (spotted Fever)
Complex growth medium
Undefined mixture
BHI broth for S.aureus
Defined growth medium
defined composition and concentration of nutrients
ex. M9 for E.coli
Bacteria growing in defined media are able to synthesize macromolecules
Bacteria growing in complex media are unable to synthesize macromolecules, and obtains them from the media
Selective media
Encourages growth of some and discourages growth of others
Differential media
Causes an observable change (biochemical change)pH, color.
- Differentiate colonies (species)
Obligate Aerobe
Pseudomonos Aeruginosa
Microaerophile
Campylobacter fetus
Facultative Anaerobe
Streptococcus gordonii
Obligate anaerobe
Porphyromonas gingivalis, oral spirochetes (many dental pathogens)
Halophiles
Extreme Saltwater 3%
human saline concentration (0.85%)
Cheeks, Lips, Palate (Environment)
-Desquamation
-Saliva a major influence
-Microflora has low diversity
-Facultative anaerobes
-Streptococcus spp. predominate.
- Some periodontal pathogens persist by invading buccal cells
Teeth (environment)
- Non shredding surface
- Stagnant Sites; Food impaction possible
- Diverse microfora; Site variation
-Many obligate anaerobes
-Influenced by saliva and GCF - Streptococcus, Actinomyces, Veilonella,Fusobacterium,Prevotella,Treponema, unculturable organisms.
Tongue (environment )
- Highly papillate surface
- Some anaerobic sites
- Desquamation
- Diverse microflora
- Facultative and Obligate anaerobes
- Streptococcus, Actinomyces, Rothia, Neisseria, some gram negative anaerobes
Mouth 35-36C
Healthy gingiva sulcus= 33-36C
Periodontal disease=39C
Palate 7.34 , buccal 6.3
Gingival Crevice 6.9
Disease=7.4 plus
Caries-acidic
Aerobic Respiration
O2 is terminal e- acceptor
Anaerobic Respiration
e- acceptor is NOT O2 (inorganic molecules ex. NO3,NO2)
Fermentation
NO O2 inorganic e- acceptor
- Use organic compounds as e- acceptor
