Bacterial Nutrition Flashcards
The metabolic capacity of bacteria is enormous because
have large SA to volume ratios, close contact with environment, accumulate nutrients quickly, grow rapidly
bacteria can be fulminant, meaning
infection begins suddenly, worsens quickly
Autotrophic metabolism
fix CO2, CO2 is used as building blocks
Chemoautotroph
fixing CO2 from the oxidation/reduction of inorganic ions
Photoautotroph
fixing CO2 from light energy
Heterotrophic bacteria
utilize organic molecules as building blocks via the oxidation of organic compounds
All bacteria that cause disease in humans are
heterotrophs
heterotrophs utilize organic molecules in what order
carbohydrates, proteins, lipids
fastidious
complex growth requirements, will not grow on blood agar
Non-fastidious
will grow on blood agar
optimal growth occurs closer to the __________ temperature
maximum
the minimal temperature growth range for bacteria is defined by
reduced enzyme activity and reduced membrane fluidity
the maximal temperature growth range for bacteria is defined by
protein denaturation
Mesophile
growth occurs between 20 - 55C
Thermophile
growth occurs at >55C
Psychrophile
growth occurs at <20C; a few human pathogens are facultative psychrophiles
Most pathogens are ________ and growth best at __________ temperature
mesophiles; 35-36C
Is refrigeration a good means to obtaining sterile conditions? why?
No, some human pathogens are facultative psychrophiles and grow at <20C
Obligate aerobic organisms
ONLY grow in the presence of O2
Examples of Obligate aerobic organisms
Mycobacterium tuberculosis
Microaeropilic organisms
grow in the presence of reduced concentrations of O2
Examples of Microaeropilic organisms
Campylobacter
Facultative anaerobic organisms
use aerobic respiration when O2 is plentiful (initial infection), switch to fermentation when O2 is unavailable (number of bacteria increase at infection site)
aerotolerant anaerobic organisms
can grow in the presence of O2, but grow best without
Obligate anaerobic organisms
only grow in the absence of O2 and utilizes fermentation
Examples of aerotolerant anaerobic organisms
Lactobacillus
Examples of Obligate anaerobic organisms
Clostridium and Bacteroides
Most human pathogens are
facultative anaerobic organisms
Most human pathogens are
heterotrophic, mesophilic, facultative anaerobes
Th effect of O2 on anaerobes
generation of toxic superoxides and hydrogen peroxides (O2-, H2O2), inhibiting growth or causing death
Oxygen tolerant (aerobes) bacteria
produce enzymes that detoxify superoxides and hydrogen peroxides (superoxide dismutase (SOD), catalase)
Superoxide dismutase
catalyzes the reaction of a superoxide anion + H2 = H2O2 + O2
Catalase
catalyzes the reaction of H2O2 to 2 H2O + O2
Oxygen intolerant (anaerobes) bacteria
toxic by products are produced from growth in O2, but they lack the enzymes to detoxify them
What antibiotics are used to treat anaerobic infections?
metronidazole, tindazole
Inorganic requirements of certain bacteria
inorganic requirements too high or too low can trigger changes in bacterial phenotypes
Low [Fe] induces
C. diptheriae to produce diphtheria toxin
Low [Ca] induces
plague bacterium to produce exotoxins
Low [Mg] induces
S. aureus to produce toxic shock syndrome toxin TSST-1
Heterotrophic metabolism is a __________ pathway
catabolic (oxidation of glucose into simpler carbon compounds)
Glycolysis
partially oxidize organic matter to enter other pathways and generate ATP
TCA cycle
reducing power to oxidize Carbon into CO2 to generate ATP and intermediates for anabolic pathway
fermentation pathway
substrate level phosphorylation to generate ATP, reduces compounds
Respiration
proton motive force that occurs in a membrane vesicle for ATP synthesis during the oxidation of NADH
Electron Transport Chain
transfer of electrons and hydrogen from NADH2 to terminal electron acceptors (O2)