Microbial Nutrition & Growth

Any nutrient that must be provided to an organism; they can’t create it on their own

essential nutrient

Roles in cell structure and metabolism and needed in large amounts

macronutrients

Roles in enzyme function and needed in small amounts

micronutrients

3 Macronutrients

carbon, hydrogen, oxygen

3 Micronutrients

manganese, zinc, nikel

An organism that must obtain its carbon in an organic form

heterotroph

An organism that must obtain its carbon as CO₂ (inorganic form)

autotroph

Function of macronutrients

cell structure and metabolism

Function of micronutrients

enzyme function

Saprobe

gets nutrients from dead/decaying matter

Parasite

gets nutrients from a living host

Optimum temperature for psychrophiles

4 degrees celsius

Optimum temperature for psychrotrophs/psychrotolerant

25 degrees celsius

Optimum temperature for mesophiles

37 degrees celsius

Thermoduric Microbes

can survive short amounts of time in extreme temperatures

Optimum temperature for thermophiles

70 degrees celsius

Optimum temperature for extreme thermophiles

125 degrees celsius

Cannot grow without oxygen present

obligate aerobes

Harmed by normal atmospheric concentrations of oxygen, but still require small amounts for metabolism

microaerophiles

Does not require oxygen, but use it when present to grow better

facultative anaerobes

does not utilize oxygen to grow, but can still survive in its presence

aerotolerant anaerobes

Lack the enzymes for tolerating oxygen and die in its presence

obligate anaerobes

What are the two enzymes that neutralize reactive oxygen by-products?

superoxide dismutase and catalase

Organisms that grow best with higher CO₂ concentrations than normally present in the atmosphere

capnophiles

Organisms that grow in habitats between a pH of 6 and 8

neutrophiles

Organisms that thrive in acidic environments

acidophiles

Organisms that thrive in alkaline conditions

alkalinophiles

Microorganisms that live in habitats with high solute concentration

osmophiles

Microorganisms that prefer high concentrations of salt

halophiles

Grow optimally at solutions of 25% NaCl, but require at least 9% NaCl

obligate halophiles

Can grow and survive in environments with high salt concentration, but does not require it to live

facultative halophiles

Non photosynthetic microbes tend to be damaged by ___ produced by contact with light

toxic oxygen byproducts

Some microbial species produce ___ to absorb and dismantle toxic oxygen

yellow carotenoid pigments

These microbes exist under pressures that can be up to 1,000 times the pressure of the atmosphere; they rupture in normal atmospheric pressures

barophiles

Both organisms benefit

mutualism

One organism benefits, the other is not harmed

commensalism

One organism benefits, the other is harmed

parasitism

Members cooperate and share nutrients

synergism

Some members are inhibited/destroyed by others

antagonism

Attached cells are stimulated to release chemicals as the cell population grows: monitors the size of the population when forming a biofilm

quorum sensing

What does ‘N’ stand for in the population growth rate equation?

starting number of cells

What does ‘T’ stand for in the population growth rate equation?

time period

What does ‘n’ stand for in the population growth rate equation?

generation number

Phase of adjustment for bacterial cells; cells are not yet multiplying

lag phase

Phase where bacterial cell number increases significantly; continues as long as adequate nutrients and a favorable environment are present

exponential growth phase

Phase where cell growth and death rate are equal; caused by depleted nutrients and oxygen as well as excretion of organic acids and biochemical pollutants

stationary growth phase

Phase where cells begin to die at an exponential rate due to buildup of wastes; speed depends on resistance of the species and how toxic the conditions are

death phase

State where many cells in a culture in the death phase stay alive but are dormant

viable nonculturable state

Used to describe microbe population size based on how cloudy the clear solution becomes

turbidity

Counting cells by looking at them under a microscope

direct cell count

Machine that electronically counts cells by scanning fluid as it passes through a tiny pipette; can only count cells

coulter counter

Machine that works similarly to a coulter counter but can measure cell size and differentiate between live and dead cells

flow cytometry

Uses real-time PCR to quantify bacteria and determine population size

genetic probing

Counts the number of colonies on a petri plate: one dot on the plate represents one colony unit

viable plate count method

What are the 3 types of radiation that can be damaging to microbes?

visible light, ultraviolet light, and ionizing radiation

What is the only way you can analyze microbe population size with culturing?

viable plate count method