Microbiology & Parasitology M2

Microbial Growth

Increase in the number of cells, not the size of the cells

Growth

the orderly increase in the sum of all the components of an organism

Budding

how some bacteria reproduce

True growth

increase in population/number of cells

Binary Fission

Asexual reproduction in bacteria where one cell divides into two

Generation Time

The time required for a cell to divide and its population to double

E. coli

shortest generation time, divides at 15 minutes

Mycotuberculosis

slow generation time

Lag Phase

Little or no cell division occurs, bacteria adapt to new environment

Log Phase

Exponential growth phase where cells are metabolically active

Stationary Phase

Period of equilibrium where cell division equals cell death

Death Phase

Decline in number of living cells as death rate exceeds growth rate

Exponential Growth

Bacterial population doubles at a constant rate

Incubation Period

Time between acquisition of microorganism and first symptoms

Cultivation

process of propagating microorganisms by providing the proper environmental conditions.

Incubator

proper environmental condition for microorganism to grow, optimal for growth

Fermentation

Energy production without oxygen by substrate phosphorylation

Respiration

Energy production involving electron transport and proton motive force

Photosynthesis

Energy production using light to generate reductants and oxidants

Carbon Source

Structural backbone of living matter autotrophs use CO2, heterotrophs use organic compounds

Nitrogen Source

Component of proteins and nucleic acids obtained from NO3, NH3, amino acids

Sulfur Source

Found in coenzymes and amino acids (cysteine, methionine)

Phosphorus Source

Component of ATP, nucleic acids, phospholipids

Magnesium & Potassium

Essential for ribosome function and enzyme activity

Calcium

Required for Gram

Sodium

Required by marine organisms for growth

Siderophores

Compounds that chelate iron and promote transport

Growth Factor

Organic compound required for growth but cannot be synthesized by the cell

Neutralophiles

Microbes that grow at pH 6.0–8.0

Acidophiles

Microbes that grow at very low pH (around 3.0)

Alkaliphiles

Microbes that grow at very high pH (up to 10.5)

Psychrophiles

Grow at -5 to 15°C,

Psychrotrophs

Grow at 20 to 30°C, cause food spoilage

Mesophiles

Grow at 30 to 37°C, includes most pathogens

Thermophiles

Grow at 50 to 60°C

Hyperthermophiles

Grow above 80°C, near boiling water under pressure

Heat Shock Response

Bacteria synthesize heat

Cold Shock

Rapid cooling that kills many bacteria

Obligate Aerobes

Require oxygen for growth

Facultative Anaerobes

Can grow with or without oxygen

Microaerophiles

Require small amounts of oxygen (2–10%)

Obligate Anaerobes

Cannot tolerate oxygen

Aerotolerant Anaerobes

Do not use oxygen but tolerate its presence

Catalase

Enzyme that breaks down hydrogen peroxide into water and oxygen

Superoxide Dismutase

Enzyme that detoxifies superoxide radicals

Halophiles

Grow in high salt concentrations

Osmophiles

Grow in high sugar concentrations