Lecture 4 - Microbial Growth Requirements Flashcards
___ is the 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; physical
What are the factors affecting microbial growth? (3)
- Biochemical Factors (Nutrition)
- Generation Time
- Physical Factors
What are the biochemical factors (nutrition) affecting microbial growth? (3)
- Macronutrients
- Micronutrients
- Vitamins
____ supplies cells with chemical tools (nutrients) that they need to make monomers of the macromolecules that mainly comprise microbial cells.
Microbial Nutrition
____ are made up of chemical elements; they are extracellular substances that provide a microbial cell with materials to (1) build protoplasm and (2) generate energy.
Nutrients
____ are nutrients required in relatively larger amounts.
Macronutrients
____ are nutrients required in lesser quantities.
Micronutrients
A ____ is any nutrient material prepared/used for the growth and cultivation of microorganisms in the laboratory.
Culture Medium
What is Culture Media for? (3)
- 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
What are the types of culture media (based on physical state or consistency)? (3)
- Liquid
- Semi-solid
- Solid
___ is a type of culture media that consists of the ff:
composition: w/ NO solidifying agent
purpose/s: Inoculum Preparation; Fermentation Test
examples: Nutrient broth; Lactose broth
Liquid Culture Medium
___ is a type of culture media that consists of the ff:
composition: w/ 0.1-0.5% solidifying agent
purpose/s: Motility Test
examples: Sulfur Indole Motility (SIM) Medium
Semi-Solid Culture Medium
___ is a type of culture media that consists of the ff:
composition: w/ 1.5-2.0% solidifying agent
purpose/s: Colony Morphology Observation; Hemolysis and Pigmentation Characterization
examples: Nutrient Agar; Blood Agar
Solid Culture Medium
____ is a complex polysaccharide (derived from red algae). It is used as a solidifying agent for culture media in Petri plates, slants, and deeps. It has no nutritive value and is generally not metabolized by microbes. It is not affected by the growth of bacteria.
Agar
Agar liquifies at ____.
Agar solidifies at ____.
100°C
~40°C
What are the types of culture media (based on chemical composition)? (2)
- Synthetic or Chemically-Defined Culture Media
- Complex Culture Media
____ is a type of culture media that consists of the ff:
- all components are chemically-defined (precise nutrient composition and amounts.
- examples: Glucose, Inorganic Salt Phosphate
Synthetic or Chemically-Defined Culture Medium
____ is a type of culture media that consists of the ff:
- not all components are chemically-defined.
- examples: Nutrient Agar, Yeast Extract
Complex Culture Medium
____ is a type of culture media prepared from pure chemicals and the exact chemical composition (kinds and amounts) is known.
Synthetic or Chemically-Defined Culture Medium
What are some disadvantages of using synthetic (chemically-defined) culture medium? (3)
- preparation is time-consuming
- microorganisms grow relatively slow
- prepared only for microorganisms with known nutritional requirements
____ is a chemically undefined medium and its precise chemical composition (kinds) is unknown. It contains certain similar ingredients but its chemical composition varies slightly from batch to batch. It is made from extracts from natural materials (beef, blood, casein, yeast, soybeans).
Complex Culture Medium
What are some advantages of using complex culture medium? (2)
- easy to prepare
- support rapid growth of most microorganisms
What are the types of culture media (based on principal purpose, function, or application? (5)
- General Purpose
- Differential
- Selective
- Enrichment
- Assay
What type of culture media consists of the ff:
characteristics: can support most or almost all types of species
examples: Nutrient Agar, Tryptic Soy Agar, Brain Heart Infusion Agar
General Purpose
What type of culture media consists of the ff:
characteristics: can distinguish visually one type of bacteria from another
examples: Eosin
Differential
What type of culture media consists of the ff:
characteristics: allows the growth of a specific type of microorganism only
examples: Methylene Blue, Mannitol Salt Agar (MSA)
Selective
What type of culture media consists of the ff:
characteristics: used to increase the number of microorganisms with unusual physiological
characteristics; contains special nutrients for microorganisms of interest
examples: Cellulose Agar, Petroleum Broth, Blood Agar
Enrichment
What type of culture media consists of the ff:
characteristics: used for assay of vitamins, amino acids, antibiotics; may be used for qualitative or quantitative production of a compound by a microorganism
examples: Fermentation Media, TSI Agar, Vitamin B12 Assay Medium
Assay
___ is a type of culture media that allows the growth of a specific type of microorganism only and suppresses the growth of others. It contains selective agents/additives/toxic chemicals (salts, dyes, antibiotics, and other inhibitors). It requires an extreme pH value or an unusual carbon source to favor the growth of a particular organism.
Selective Medium
What are some examples of selective media? (3)
- Thayer-Martin Agar (Neisseria gonorrhoeae)
- NA with Penicillin (Gram-negative bacteria)
- Thiosulfate Citrate Bile Salts Sucrose (TCBS) Agar
____ is a type of culture media that can distinguish or differentiate visually one type of bacterium from another. It identifies microorganisms by the appearance of their colonies and exploits the ability of a particular microorganism to change the appearance of the medium.
Differential Medium
What are some examples of differential media? (2)
- Blood Agar (Streptococcus species)
- Mac-Conkey Agar (E. coli and lactose fermenters)
____ 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
____ are exoenzymes produced by some bacteria that lyse red blood cells and degrade hemoglobin.
Hemolysins
Beta-hemolysin breaks down the red blood cells and hemoglobin completely. This leaves a clear zone around bacterial growth. Such results are referred to as ____.
β-hemolysis (beta hemolysis)
_____ partially breaks down the red blood cells and leaves a greenish color behind.
α-hemolysis (alpha hemolysis)
The greenish color left behind by α-hemolysis (alpha
hemolysis is caused by the presence of _____, a by-product of the breakdown of hemoglobin.
Biliverdin
____ refers to if the organism does not produce hemolysins and does not break down the blood cells, no clearing will occur.
γ-hemolysis (gamma hemolysis)
____ is a type of culture media that is used to increase the number of microorganisms with unusual physiological characteristics (pathogens from a mixed culture). It contains special nutrients for the microbe of interest and inhibitory substances to suppress unwanted microorganisms.
Enrichment Medium
____ is a type of media that is used for the assay of vitamins, amino acids, and antibiotics. It is used for qualitative or quantitative production of such a compound by a microorganism. It is of prescribed composition.
Assay Medium
____ is a type of culture media that contains an indicator that changes its color when a bacterium grows in them. Some of its examples are Blood Agar and Mac Conkey.
Indicator Medium
___ is a type of culture media that contains any fermentable substances (glucose, arabinose, lactose, starch). It consists of 1% of the sugar in peptone water. It contains a small tube (Durham tube) for the detection of gas by the bacteria.
Sugar Medium
____ is a differential medium that contains 1% lactose, 1% sucrose, and 0.1% glucose (dextrose), ferrous sulfate, and the pH indicator phenol red. This test is normally performed on Gram-negative bacteria. It is also used to differentiate enterics based on the ability to reduce sulfur and ferment carbohydrates.
Triple Sugar Iron (TSI) Agar
____ is a type of culture media that is used for transporting samples (prevents microbial proliferation; maintains the viability of microorganisms). Some of its examples are Stuart’s medium (non-nutrient soft agar gel containing a reducing agent); buffered glycerol saline (for enteric bacilli).
Transport Medium
___ is a type of culture media that used to provide additional information for the identification of the bacterium. Some examples of this culture media are Triple Sugar Iron (TSI) Agar (Sugar Fermentation), SIM Medium (Indole Test), Citrate Utilization, and Christensens Urease Medium (Urease Test).
Biochemical Reaction Medium
___ is a test used to detect indole production by an organism. A positive test is indicated by a pink ring. A negative test is indicated by a yellow ring.
Indole Test
_____ is done in Simmon’s Citrate medium. It is used to detect the ability of certain bacteria to utilize citrate as the sole source of carbon. It contains sodium citrate and bromothymol blue as the indicator.
Citrate Utilization Test
What are the two types of culture media if based on oxygen requirement? (2)
- Aerobic Media
- Anaerobic Media
____ is a type of culture media used to grow anaerobic organisms. Some examples of this are Robertson’s cooked meat medium and Thioglycolate medium.
Anaerobic Medium
____ is a type of culture media that is used to grow aerobes or aerobic microorganisms.
Aerobic Medium
What are the physical factors affecting microbial growth? (7)
- pH
- Temperature
- Oxygen Concentration
- Moisture
- Hydrostatic Pressure
- Osmotic Pressure
- Radiation
____ is an expression of hydrogen ion concentration in water.
pH
pH values less than 7 – ____
pH values greater than 7 - ____
acidic
basic
The optimum pH for most bacteria is near neutrality or ____.
pH 7
What is the pH range of each classification of organisms based on pH?
- Acidophiles < pH 5.4
- Neutrophiles pH 5.4 - 8.5
- Alkaliphiles pH 7.5 - 11.5
____ are acid-loving organisms. They can be found in acidic lakes and/or in the gastrointestinal tract. These include most fungi since they are acid-tolerant and their optimum temperature is 5 or below. Also include some algae, bacteria, and several archaea. A high H+ concentration is required for these organisms to maintain cell membrane stability.
Acidophiles
____ include most human disease-causing bacteria (human blood and tissues pH = 7.2 - 7.4) and protozoans and most bacteria (pH 6.5 - 7.5).
Neutrophiles
____ are base-loving organisms that live in soda lakes and/or high-carbonate soils. Such organisms are Bacillus, Vibrio cholerae (pH 9), Alcaligenes
faecalis (>pH 9), and Agrobacterium (pH 12). Some also produce hydrolytic enzymes (proteases and lipases).
Alkaliphiles
____ is one of the most, if not the most, important environmental factors affecting the growth and survival of microorganisms.
Temperature
What are the three critical temperatures (affecting enzyme function) or the three cardinal temperatures? (3)
- Minimum Growth Temperature
- Optimum Growth Temperature
- Maximum Growth Temperature