MODULE 4.1 Flashcards
increase in the number of cells or microbial population rather than in the size of individual cells
Microbial Growth
To increase the population of
microorganisms, their _____ and
_____ requirements must be provided.
nutritional and physical
Factors Affecting Microbial Growth
biochemical factors (nutrition)
physical factors
generation time
it is supplying cells with chemical tools (nutrients) they need to make monomers of macromolecules that mainly comprise microbial cells
Microbial Nutrition
- made up of chemical elements
- extracellular substances that provide the microbial cell with materials
Nutrients
Nutrients are extracellular substances that provide the microbial cell
with materials to (2)
Build protoplasm
Generate energy
Biochemical factors (nutrition)
Macronutrients
Micronutrients
Vitamins
Macronutrients
Protein, lipid, polysaccharide, LPS DNA, and RNA
Micronutrients
C, H, O, N, P, S, K, Na, Ca, Mg, Fe
Vitamins
B1 (Thiamine), B2 (Riboflavin), B6 , B12 (Cobalamine), K, Biotin, Folic acid
any nutrient material prepared/used for the growth and cultivation of microorganisms in the laboratory
Culture Medium
What are Culture Media for?
- for the growth and maintenance of microbial cultures
- to favor the production of particular compounds
- to study microbial action on some constituents of the medium
Types of Culture Media (physical composition)
Liquid
Semi-solid
Solid
Types of Culture Media (chemical composition)
Synthetic or chemically-defined
Complex
Types of Culture Media (principal purpose, function, or application)
General Purpose
Differential
Selective
Enrichment
Assay
Nutrient Agar
Tryptic Soy Agar
Brain Heart Infusion Agar
General purpose culture media
Eosin Methylene Blue
Mannitol Salt Agar
Blood agar (Streptococcus species)
Mac-Conkey agar (E. coli and lactose fermenters)
Differential
contains general nutrients and 5% sheep blood.
It is useful for cultivating fastidious
organisms and for determining the hemolytic capabilities of an organism.
Blood agar
Some bacteria produce different types of exoenzymes that lyse red blood cells
and degrade hemoglobin;
hemolysins
different types of hemolysins - result in blood agar
beta hemolysis - clear zone
Alpha-hemolysin - greenish color
gamma hemolysis - no clearing
Thayer-Martin agar (Neisseria gonorrhoeae)
NA with penicillin (Gram-negative bacteria)
Thiosulfate Citrate Bile Salts Sucrose (TCBS) Agar;
Selective culture medium
Cellulose agar (for cellulolytic microorganisms)
Petroleum broth (for petroleum-utilizers)
Blood agar (hemolytic bacteria)
Enrichment culture medium
fermentation media
TSI agar
Vitamin B12 assay medium
Assay culture medium
Other Types of Culture Media
Indicator Medium
Sugar Medium
Transport Medium
Biochemical Reaction Medium
Aerobic Media and Anaerobic Media
medium with no solidifying agent,
used for inoculum preparation, fermentation test
Nutrient Broth; Lactose Broth
liquid culture media
medium with 0.1- 0.5% solidifying agent,
used for motility test,
Sulfur Indole Motility (SIM) Medium
semi-solid culture media
medium with 1.5-2.0% solidifying agent,
used for Colony morphology observation, hemolysis and pigmentation characterization
Nutrient Agar; Blood Agar
solid culture media
types of agar solid culture medium
agar plate
agar slate
agar deep
complex polysaccharide (usually derived from red algae)
used as solidifying agent for culture media in Petri plates, slants, and deeps
Agar
T or F. Agar is affected by growth of bacteria and has nutritive value.
F.
Agar has no nutritive value; generally not metabolized by microbes and is not affected by growth of bacteria.
Agar
* Liquefies at _____
* Solidifies at _____
100°C
~40°C
medium where all components are chemically-defined (precise nutrient composition and amounts)
prepared from pure chemicals
uses: important for genetic and specific or precise studies
Glucose, Inorganic Salt, Phosphate
Synthetic or chemically- defined medium
disadvantages of synthetic medium (3)
– preparation is time-consuming
– microorganisms grow relatively slow
– prepared only for microorganisms with known nutritional requirements
medium where not all components are chemically-defined
made from extracts from natural materials (beef, blood, casein, yeast, soybeans)
use: routine purposes
Nutrient Agar, yeast extract
Complex medium
advantages of complex medium
– easy to prepare
– support rapid growth of most microorganisms
medium that can support most or almost all types of species
general purpose
medium that can distinguish visually one type of bacterium from another
exploits the ability of a particular microorganism to change the appearance of the medium
with special reagents like pH indicators and dyes
differential
medium that allows growth of a specific type of microorganism only
contains selective agents/additives/toxic chemicals (salts, dyes, antibiotics, and other inhibitors)
extreme pH value or unusual carbon source to favor growth of a particular organism
selective
selective medium used for Neisseria gonorrhoeae
Thayer-Martin Selective Agar
medium that is used to increase the number of microorganisms with unusual physiological characteristics; contains special nutrients for microorganisms of interest
contains special nutrients for microbes of interest and inhibitory substances to suppress unwanted microorganisms
enrichment
Enrichment medium for hemolytic bacteria
Blood Agar
medium that is used for assay of vitamins, amino acids, antibiotics; may be used for qualitative or quantitative production of a compound by a microorganism
assay
medium contains an indicator which
changes its color when a bacterium grows in them
Blood agar, Mac Conkey’s medium
indicator medium
medium containing any fermentable substances
consists of 1% of the sugar in peptone water
Sugar Medium
a small tube in sugar medium for the detection of gas by bacteria
Durham tube
is a differential and sugar medium that contains 1% lactose, 1% sucrose, 0.1% glucose, ferrous sulfate , pH indicator PHENOL RED
Used to determine the ability to:
1. Reduce sulfur to H2S
2. Lactose &/or Sucrose fermentation
3. Glucose fermentation and Gas production
Triple Sugar Iron Test (TSI)
medium used for transporting samples (prevent microbial proliferation; maintain viability of microorganisms)
Stuart’s medium, Cary-Blair, Amies
Transport medium
medium that is recommended for the preservation and transportation of Neisseria species and other fastidious organisms from the clinic to laboratory.
Transport Medium Stuart
medium used to provide additional information for the identification of the bacterium
Triple sugar iron agar (sugar fermentation); SIM Medium (Indole test); Citrate utilization; Christensens urease medium (Urease test)
Biochemical Reaction Medium
medium for SUGAR FERMENTATION
Triple sugar iron agar
- Lactose fermenters - E.coli, Klebsiella
- Non Lactose fermenters - Salmonella, Shigella
- H2S - Proteus
Used to detect indole production by
the organism.
Motility Test
Kovac’s Reagent
SIM Medium (Indole test, motility test)
(+) pink ring - E.coli
(-) yellow ring - Klebsiella, Salmonella
medium used in CITRATE UTILIZATION TEST
Test used to detect the ability of certain
bacteria to utilize citrate as the
sole source of carbon.
Sodium citrate and bromothymol blue as the indicator
Simmon’s Citrate medium
(+) blue color: Klebsiella
(-) green color: E.coli
medium used in UREASE TEST
test is used to detect organisms that produce urease.
Christensen’s urease medium
(+) pink color: Proteus, Klebsiella
(-) yellow color: E.coli, Salmonella
medium that is used to grow aerobes
- Mannitol salt agar
Aerobic medium
medium that are used to grow anaerobes
- Robertson’s cooked meat medium
- Thioglycolate medium
Anaerobic medium
anaerobic medium that uses cooked meat particles as a reducing agent that absorbs O.
most species produce gas in this medium
Robertson’s cooked meat medium
Saccharolytic species turn meat pink
Proteolytic species turn meat black with foul smell
Anaerobes that attack meat and turns meat into pink in Robertson’s cooked meat medium
Saccharolytic species
Anaerobes that attack carbohydrates in meat and turns meat into black with foul smell
Robertson’s cooked meat medium
Proteolytic species
