How can we help?

You can also find more resources in our Help Center.

168 terms

Microbial Growth and Ecology

Unit 2, SJRState, Kempke, Micro
STUDY
PLAY
What are three physical factors affecting bacterial growth?
Temperature, pH, and Osmotic pressure
Psychrophiles thrive at which temperatures?
≤15
Mesophiles thrive at which temperatures?
25-40 C
Thermophiles thrive at which temperatures?
≥40
Psychrotrophs thrive at which temperatures?
0-30 C
An example of a psychrotroph is:
Pseudomonas
Most bacteria thrive at in a narrow pH range near __________.
Neutrality
Acidophiles thrive at which pH?
<5
Alkaliphiles thrive at which pH?
>9
Neutrophiles thrive at which pH?
5.4-8.0
An example of an acidophile is:
H. pylori
An example of a mesophiles is:
E. coli, Salmonella
Most human pathogens are:
Mesophiles
Hyperthermophiles thrive at which temperatures?
>80
An example of a hyperthermophile is:
T. acidophilum
An example of a hypoacidophile is:
T. acidophilum
Define facultative:
can adapt to
Osmotic pressures have to do with which compound?
NaCl
Define facultative halophile:
an organism that can adapt to higher salt concentrations
Halophiles thrive in which environment:
salt
An example of a facultative halophile is:
S. aureus
Which of the properties can be used to differentiate bacteria?
Halophile or not
Do the cells of halophiles shrink when placed in an osmotic solution?
No
Define plasmolysis:
shrinkage of the cell membrane due to high osmolarity
Define obligate halophile:
must have salt to live
What type of agar is best suited for S. aureus?
Mannitol
What is the carbon source for autotrophs?
CO2
An example of a photo-autotroph is:
photosynthesizing bacteria
What is the energy source of chemo-heterotrophs and chemo-autotrophs?
Glucose
What is the carbon source of heterotrophs?
Organic Compounds/Glucose
What is the energy source of photo-heterotrophs and photo-autotrophs?
Light
Most bacteria have which energy/carbon source combination?
Chemo-heterotroph
Most humans have which energy/carbon source combination?
Chemo-heterotroph
T or F Carbon is a chemical requirement for growth
T
T or F Sodium is a chemical requirement for growth
F
T or F Nitrogen is a chemical requirement for growth
T
T or F Hydrogen is a chemical requirement for growth
F
T or F Oxygen is a chemical requirement for growth
T
T or F Sulfur and Phosphorus can be chemical requirements for growth
T
What is a component of proteins, nucleic acids, coenzymes, and cell walls?
Nitrogen
Nitrogen accounts for 12-15% of ___________ of a bacterial cell
Dry weight
Bacteria obtain Nitrogen from inorganic/organic/both sources?
Both
Define Nitrogen fixation
the conversion of Nitrogen to a usable form
What is an important component of amino acids?
Sulfur
What type of sulfur is used directly by bacteria?
Inorganic sulfate
What is an important component of nucleic acids and phospholipids?
Phosphorus
What type of phosphorus is used directly by bacteria?
Inorganic phosphate
Normal molecular oxygen that has been boosted into a higher energy state:
singlet oxygen
Toxic to cellular components, need SOD to neutralize it:
Superoxide free radical
Toxic to cells, need catalase to neutralize it:
Hydrogen peroxide
No known enzymatic system to deal with this, but has a very short half-life:
Hydroxyl radical
In obligate aerobes oxygen is:
required
In facultative aerobes oxygen is:
not required
In micoraerophiles oxygen is:
required but at levels lower than in atmosphere
In obligate anaerobes oxygen is:
toxic
Enzymes used by obligate aerobes:
SOD+, Catalase +
Enzymes used by facultative aerobes:
SOD+, Catalase +
Enzymes used by micoraerophiles:
SOD-, Catalase -
Enzymes used by obligate anaerobes:
SOD-, Catalase -
An example of an obligate aerobe:
Bacillus
An example of a facultative aerobe:
E. coli
An example of a microaerophile:
Helicobacter
An example of an obligate anaerobe:
Clostridium
A complex polysaccharide derived from red algae:
Agar
Can Agar be degraded by microorganisms?
No
At what temp does Agar liquefy?
100C
At what temp should a water bath be for Agar?
50C
The highest incubation temperature for Agar:
near 100C
A medium whose exact chemical composition is known is called a:
chemically defined medium
Chemically defined mediums are good for organisms that require:
many growth factors
Define fastidious organism:
An organism that has complex nutritional requirements
An example of a fastidious organism:
N. gonorrhoeae
You should culture fastidious organisms on which type of medium?
Chemically defined
In what type of media are the requirements for energy, carbon, nitrogen, and sulfur primarily provided by protein?
Complex media
Define peptone
small, soluble protein fragments that can be digested by most bacteria
A nutrient broth is an example of what type of media?
Complex
What is a nutrient broth called if you add agar to it?
Nutrient Agar
T or F Nutrient broth and Nutrient Agar are the same thing?
F
T or F Many bacteria have never been grown successfully on laboratory media?
T
Two examples of bacteria that have never been grown successfully in the lab?
M. leprae and T. pallidum
Which types of bacteria have not been grown successfully on laboratory media?
Obligate intracellular
What do capnophiles require for growth?
Higher concentrations of CO2
This media inhibits the growth of one type of bacteria while permitting the growth of another.
Selective media
This media does not inhibit one type of bacteria over another but allows different bacteria to display different characteristics
Differential media
An example of a differential media is
blood agar
An example of a selective and differential media at the same time is:
Mannitol
Mannitol is selective for
halophiles
A differential medium that differentiates lipase producing bacteria
Spirit Blue Agar
This selective and differential media is selective to gram negative coliforms:
EMB
This selective and differential media is used to differentiate lactose vs. sucrose fermentation:
EMB
Which bacteria is negative on Spirit blue (non-lipase producing)?
E.coli
Which bacteria is positive on Spirit blue (lipase-producing)?
Serrata
Is Mannitol selective, differential, or both?
Both
Mannitol is selective for:
Staph
Mannitol is differential for:
Mannitol fermenters
An example of a non-Mannitol fermenter:
S. epidermidis
An example of a Mannitol fermenter is:
S. aureus
Is Spirit Blue Agar selective, differential, or both?
Differential
Spirit Blue is differential for:
lipase producing bacteria
An example of a lipase producing bacteria:
Serratia
An example of a non-lipase producing bacteria:
E. coli
Is EMB selective, differential, or both?
Both
EMB is selective for:
gram - microbes
EMB is differential for:
lactose vs. sucrose fermentation
Lactose fermenters form _____ colonies on EMB.
Colored
Non-lactose fermenters form ______ colonies on EMB.
Non-colored
Is MacConkey Agar selective, differential, or both?
Both
MacConkey is selective for:
gram - enterics
MacConkey is differential for:
lactose vs. non-lactose fermenting
What in MacConkey agar inhibits the growth of gram + bacteria?
Crystal violet and bile salts
What is the pH indicator in MacConkey?
Neutral Red
Strong lactic acid colonies form what on MacConkey?
A pink halo
If a bacterium produces lactic acid what color is it on MacConkey?
Pink
An example of a lactic acid producer via MacConkey:
E. coli
This type of culture is designed to increase very small numbers of desired organisms to detectable amounts.
Enrichment Cultures
An example of substances to be tested using enrichment cultures include:
soil or fecal samples, drinking water txt facilities
An increase in bacterial numbers is called:
growth
A simple splitting of a parent cell into two daughter cells is called:
binary fission
When a cell forms a small initial outgrowth that enlarges until its size approaches that of the parent cell, and then separates is called:
budding
The time required for a bacterial cell to divide is called:
generation time
What is the relative generation time for most bacteria?
30 - 60 minutes
Do pathogens generally have a short or long doubling time?
Short
Which pathogen has a generation time of 10 - 30 days?
M. leprae
Bacteria in a free-floating state are said to be:
planktonic
The phase in which there is little to no cell division and the microbial population is undergoing intense metabolic activity:
Lag
The phase in which exponential growth occurs and cellular reproduction is most active:
Log
The phase in which the number of deaths equals the number of new cells:
Stationary
The phase in which the number of deaths exceeds the number of new cells:
Death
Microbes are most sensitive to antibiotics during which phase?
Log
Bacterial growth can be measured either ___________ or __________.
Directly/Indirectly
Tell whether the following is an indirect or direct measure: Serial dilution and standard plate counts.
Direct
Tell whether the following is an indirect or direct measure: Direct microscopic counts.
Direct
Tell whether the following is an indirect or direct measure: Most probable number.
Direct
Tell whether the following is an indirect or direct measure: Filtration.
Direct
Tell whether the following is an indirect or direct measure: Turbidity
Indirect
Tell whether the following is an indirect or direct measure: Spectrophotometry
Indirect
Tell whether the following is an indirect or direct measure: Metabolic Activity
Indirect
Tell whether the following is an indirect or direct measure: Dry Weight
Indirect
How many colonies fall constitute a "countable" range?
30-300
What measures the number of viable cells?
Plate counts
What is done to ensure that colony counts are in a countable range?
Serial dilution
A series of small dilutions is called
Serial dilution
Which type of count requires no incubation time?
Direct Microscopic Count
Which type of count requires the use of a microscope and slides?
Direct Microscopic Count
Which type of count incorporates statistical estimating?
MPN
Which type of count is used when microbes will not grow on solid media?
MPN
Which type of count is used when the quantity of bacteria is extremely small?
Filtration
Which type of count estimates bacterial numbers by measuring a population's metabolic activity?
Metabolic Activity
Obligate Anaerobe:
Clostridium
Living together:
symbiosis
These microbes carry out complete lysis of red blood cells when grown on blood agar:
beta
A facultative anaerobe:
E.coli
A relationship in which both partners benefit:
mutualism
Requires oxygen, but at lower levels than those found in the atmosphere:
microaerophile
Neutralizes free radicals
SOD
Requires higher concentration of Co2 for growth:
capnophile
Nitrogen fixing bacterium
Rhizobium
Breaks down hydrogen peroxide
catalase
Conversion of atmospheric Nitrogen to a usable form:
fixation
Microbe that grows on Mannitol Salt Agar:
Staphylococcus
Medium that inhibits the growth of one type of bacteria but permits the growth of another:
selective
Uses carbon dioxide as its carbon source:
autotroph
An acid loving microbe:
acidophile
A differential medium:
blood agar
A fastidious microbe:
Neisseria
Optimum temperature for growth is 25C:
psychrotroph
A photosynthetic bacteria:
photo-autotroph
Obligate Aerobe:
Pseudomonas