MICROBIAL GROWTH Flashcards
Increase in the population of cells is called a
culture
Cell division is by an asexual process called
binary fission
the time it takes to divide
(double) is called
generation time
Organisms are adjusting to the environment
(little or no division).
Lag Phase
They are synthesizing DNA, ribosomes and
enzymes to breakdown nutrients, and to be
used for growth
Lag Phase
Division is at a constant rate (generation time)
but varies with species, temperature and media.
Log or Logarithmic phase
In Logarithmic Phase, cells are most susceptible to
inhibitors
Dying and dividing organisms are at an
equilibrium.
Stationary phase
Stationary phase
Death is due to _______. Cells are
smaller and have fewer ribosomes
reduced nutrients, pH changes,
toxic waste and reduced oxygen
Stationary Phase
In some cases cells do not die but they are not
Multiplying
The population is dying in a geometric fashion
so there are more deaths than new cells.
Death or Decline phase
Deaths are due to the factors in ______in addition to lytic enzymes that are
released when bacteria lyse.
stationary
phase
Population doubles every 20 minutes
Exponential Phase/Log Phase
Factors That Affect Microbial Growth
- Availability of
Nutrients - Moisture
- Temperature
- pH
- Osmotic
Pressure - Barometric
Pressure - Gaseous
Atmosphere
Components of Carbohydrates
C, O, H
Components of Protein
C, O, H, N
Electrolytes include
Na, K, Cl, Mg, Ca, Fe, I, Zn
Other growth factors are organized into three
categories:
Purines and Pyrimidines
Amino Acids
Vitamins
required for
synthesis of nucleic acids (DNA and RNA)
Purines and pyrimidines
Five membered ring:
Six membered ring:
Purine
Pyrimidine
required for the synthesis of
proteins
Amino Acids
Amino acids produced by the body, and do not need exogenous source
Non-essential Amino Acid
Amino Acids which are not produced in the body and are acquired through an external source
Essential Amino Acids
Vitamins: co____
Minerals: co____
enzymes
factors
needed as coenzymes and
functional groups of certain enzymes
Vitamins
(organisms that use
CO2 as a carbon
source)
Autotrophs
(organisms that use
organic compounds
as a carbon source)
Heterotrophs
(organisms that use
light as an energy
source)
Phototrophs
(organisms that use
chemical as energy
source)
Chemotrophs
(organisms that use
CO2 as a carbon
source) and (organisms that use
light as an energy
source)
Photoautotrophs
(organisms that use
organic compounds
as a carbon source) and (organisms that use
light as an energy
source)
Photoheterotrophs
(organisms that use
CO2 as a carbon
source) and (organisms that use
chemical as energy
source)
Chemoautotrophs
(organisms that use
organic compounds
as a carbon source) and (organisms that use
chemical as energy
source)
Chemoheterotrophs
is essential to all life on Earth.
water
Cells are composed of between______% water
70—95
All living organisms require water to carry out
their normal ____, and most will
die in environments containing too little
moisture.
metabolic processes
complete drying process
Desiccation
the
temperature at which the microorganisms grows
best
Optimum growth temperature
– below
this, the microorganisms cease to grow
Minimum growth temperature
above
this, the microorganisms die
Maximum growth temperature
Range in between the MIN. GT and MAX. GT
Temperature range
microorganisms that grows at
temperature of 50-60°C
Thermophiles
microorganisms that grow best at
moderate temperature of 20-40°C
Mesophiles
Pathogenic infections are considered and categorized as
Mesophiles
– prefer cold temperature of 10-
20°C
Psychrophiles
OGT is 4°C (refrigerator
temperature
Psychrotrophs
can tolerate or endure
very cold temperature of less than –4°C
Psychrodurics
refers to the hydrogen ion
concentration of a solution and, thus, the acidity
or alkalinity of the solution.
pH
Most microorganisms prefer a pH of
neutral or slightly
alkaline growth medium (pH 7.0–7.4)
is the pressure that is exerted
on a cell membrane by solutions both inside
and outside the cell.
Osmotic Pressure
Normal salt conc.
Isotonic
Diluted salt conc.
Hypotonic
Saturated salt conc.
Hypertonic
(shrinkage of plasma membrane away from the cell wall) in hypertonic
plasmolysis
(leakage of cytoplasm from the cell)
plasmotypsis
thrives at high salt concentration such as V. cholerae
Halophilic
survive at high salt concentration such as S. aureus
Haloduric
Atmospheric pressure=
Barometric Pressure
serves as electron acceptor in aerobic
respiration.
Oxygen
Bacteria can be divided into the
following groups based on their oxygen
requirements:
Obligate Aerobe
Microaerophilic
Facultative Anaerobe
Obligate Anaerobe
Capnophile
Glucose is completely oxidized to CO2 and
H2O, requiring 21% oxygen.
Obligate aerobe
The metabolic process is comparable to
obligate aerobes but requires 1-15 % oxygen.
Microaerophilic
In the absence of O2, glucose undergoes
glycolysis to pyruvic acid, and then fermentation
takes place.
Facultative anaerobe
Glucose undergoes glycolysis to pyruvic acid,
then fermentation or anaerobic respiration in
which oxygen is not the final electron acceptor.
Obligate anaerobe
Some organisms use ___, ____, ____, as their final electron acceptor.
nitrate, sulfate or
carbonate
Requires carbon dioxide to survive.
Capnophile
