Microbial nutrition and growth Flashcards
How can organisms be classified?
by nutrient pattern
What is the carbon source for autotrophs (producers)?
CO2
What is the carbon source for heterotrophs (consumers)?
organic compounds
What are examples of autotrophs?
plants, algae, some bacteria, phytoplankton
What are examples of heterotrophs?
animals, fungi, most protozoa, most bacteria
What is the energy source for phototrophs?
light
What is the energy source for chemotrophs?
redox of organic/inorganic molecules
What is the carbon source for photoautotrophs?
CO2
What is the energy source for photoautotrophs?
light
What are examples of photoautotrophs?
photosynthetic bacteria
plants
What is the carbon source for chemoautotrophs?
CO2
includes some bacteria
What is the energy source for chemoautotrophs?
inorganic compounds
What is the carbon source for photoheterotrophs?
organic compounds
What is the energy source for photoheterotrophs?
light
What is an example of a photoheterotroph?
some bacteria
What is the carbon source for chemoheterotrophs?
organic compounds
What is the energy source for chemoheterotrophs?
organic compounds
What are examples of chemoheterotrophs?
animals, most bacteria, many protists, parasitic plants
What are psychrophiles?
cold-loving
exist in polar regions
What are mesophiles?
moderate temp loving
disease-causing microbes
like human body temp
What are thermophiles?
heat loving
hot compost piles
What are hyperthermophiles?
extreme thermophiles
archaea
volcanic hot springs
What are neutrophiles?
like pH 6.5-7.5
most bacteria
What are acidophiles?
like pH below 2
sulfur bacteria in coal mines
What is osmotic pressure?
the pressure required to stop water from diffusing through membrane by osmosis
What happens in a hypotonic environment?
low solute=low pressure
water goes into the cell
cell bursts (lysis)
What happens in a hypertonic environment?
high solute=high pressure
water goes out of cell
cell shrivels
What are hypertonic solutions the basis for?
food preservation
What are obligate halophiles?
require high osmotic pressure (high salt)
up to 30%
Dead Sea
What are facultative halophiles?
tolerate high osmotic pressure but don’t require it
2-15%
exist on human skin
What is carbon needed for?
organic macromolecules
What is nitrogen needed for?
nucleic acids and proteins
What is phosphorus needed for?
nucleic acids
phospholipids
What is oxygen needed for?
aerobic respiration
What is an obligate aerobe?
need oxygen to grow
growth at the top
What is an obligate anaerobe?
uses no oxygen to grow
growth at the bottom
What is a facultative anaerobe?
can grow with no oxygen but prefers it
higher concentration of growth at top but spread out everywhere else
What is a micro-aerophile?
require low amount of oxygen to grow
growth somewhere in the middle
What are aerotolerant anaerobes?
tolerate air but don’t use it
fermentation
What is autoxidation?
oxygen in environment is converted into oxygen free radicals in the cell
What happens in aerobic respiration?
uses oxygen
additional oxygen free radicals are produced as a consequence of aerobic respiration
How oxygen free radicals get electrons?
oxidize molecules which results in cell damage
What is the 2 type process to eliminate oxygen free radicals?
superoxide dismutase
catalase/peroxidase
What happens in superoxide dismutase?
converts radicals to hydrogen peroxide
What happens in catalase/peroxidase?
neutralizes H202
catalase- H202 to H20 and 02
peroxidase- H202 to H20
What ions are found naturally in water and media components?
iron
copper
zinc
function as inorganic cofactor for enzyme
How do bacteria divide?
binary fission
What is generation time?
time it takes for a cell population to double
What happens during the lag phase?
intense activity preparing for population growth
What happens during log (exponential) phase?
exponential increase in population
What happens during stationary phase?
period of equilibrium
microbial deaths balance production of new cells
What happens during death (decline) phase?
population is decreasing at a logarithmic rate
How do you measure bacterial growth directly?
plate counts
membrane filtration
microscopic counts
What is plate counting?
count CFUs on solid culture medium
What is membrane filtration?
small quantities of bacteria
bacteria trapped on filter, filter transferred to culture medium; count CFUs
Describe microscopic counting
bacteria mixed w/ dye
load volume on cell counter
living cells counted under scope
cells/mL
What are indirect ways to measure bacteria?
turbidity (cloudiness)
dry weight
metabolic activity
Describe the turbidity method
Light absorbance increases with cloudiness
Describe the dry weight method
weigh out powdered form of bacteria
more weight=more growth
Describe metabolic activity method
metabolic product measured (lactic acid)
more acid=more growth
