p.2
Nutrient Sources for Bacteria
How do environmental conditions affect bacterial nutrition?
They are constantly changing.
p.3
Temperature and pH Requirements for Bacterial Growth
What temperature range is generally optimal for bacterial growth?
Typically between 20°C to 37°C, depending on the species.
p.6
Temperature and pH Requirements for Bacterial Growth
What temperature range do psychrotrophs thrive in?
20-30 ℃, with a minimum of 0-7 ℃.
p.11
Types of Culture Media
What are defined culture media?
Media where all components and their concentrations are known.
p.22
Methods for Quantifying Bacterial Growth
What method is used to quantify bacterial growth in liquid media?
Count cells in suspension.
p.22
Methods for Quantifying Bacterial Growth
What is another method to measure bacterial growth in a turbid culture?
Measure the density of the culture.
p.17
Types of Culture Media
How would you classify media that contains Xylose as the only carbon source and a pH indicator dye?
Differential, as the pH indicator differentiates fermenting from non-fermenting organisms.
p.15
Types of Culture Media
What type of agar is MacConkey Agar?
Selective and differential.
p.15
Selective and Differential Media
What type of bacteria can grow on MacConkey Agar?
Only Gram-negative bacteria.
p.23
Methods for Quantifying Bacterial Growth
What issue can arise from clumped cells in plate counting?
Clumped cells can lead to inaccurate colony counts.
p.2
Nutrient Sources for Bacteria
What is a growth limitation for bacteria?
The minimum amount of nutrient required.
p.2
Nutrient Sources for Bacteria
What can impose environmental limits on bacteria?
Environmental limits regardless of nutrient supply.
p.1
Bacterial Growth Phases and Growth Curves
What does bacterial growth look like in a lab?
It typically appears as colonies on agar plates or turbidity in liquid cultures.
p.19
Bacterial Growth Phases and Growth Curves
What is the pattern of growth in a bacterial population?
1, 2, 4, 8, etc., or 2^0, 2^1, 2^2, 2^3,..., 2^n (where n = the number of generations).
p.20
Bacterial Growth Phases and Growth Curves
What is synthesized during the lag phase?
New biomolecules necessary to metabolize the substrates present in the medium.
p.5
Classification of Bacteria Based on Carbon and Energy Sources
What do lithotrophs use as their electron source?
Electrons from inorganic compounds (e.g., H₂O, HS⁻, S, NH₄⁺, Fe²⁺).
p.21
Bacterial Growth Phases and Growth Curves
What limits population growth during the stationary phase?
Exhaustion of available nutrients and accumulation of inhibitory metabolites or end products.
p.9
Nutrient Sources for Bacteria
What factors contribute to the diverse nutritional needs of bacteria?
Diverse environments and genetics.
p.10
Types of Culture Media
What are culture media?
Preparations that support the growth of microorganisms.
p.10
Types of Culture Media
What are the three forms of culture media?
Liquid, semi-solid, and solid.
p.1
Types of Culture Media
How can we culture bacteria based on their environmental needs?
By providing the necessary nutrients and conditions in culture media.
p.1
Types of Culture Media
What are the different kinds of culture media?
Selective media, differential media, and enriched media.
p.15
Applications of Bacterial Culture in Diagnostics
What are the controls used for testing an unknown organism's ability to ferment lactose?
Positive control: Gram-negative lactose fermenting; Negative control: Gram-positive.
p.14
Types of Culture Media
What type of agar is MacConkey Agar?
Selective and differential.
p.3
Nutrient Sources for Bacteria
What are the primary nutrients required for bacterial growth?
Carbon, nitrogen, phosphorus, sulfur, and trace elements.
p.3
Oxygen Requirements and Tolerance in Bacteria
What is the significance of oxygen tolerance in bacteria?
It determines whether bacteria are aerobic, anaerobic, or facultative anaerobes.
p.26
Applications of Bacterial Culture in Diagnostics
What type of media do hospitals and diagnostic centers use to diagnose diseases caused by bacterial pathogens?
Selective and differential media.
p.9
Nutrient Sources for Bacteria
How can we support the nutritional needs of bacteria for growth?
By understanding and providing the appropriate nutrients based on their diverse needs.
p.10
Types of Culture Media
Why might a researcher choose different types of culture media?
To meet specific growth requirements of microorganisms.
p.10
Types of Culture Media
Why is it important to study microorganisms?
To understand their roles and behaviors in various environments.
p.23
Methods for Quantifying Bacterial Growth
What is the purpose of plate counting in bacterial growth measurement?
To count the number of individual colonies on the plate.
p.17
Applications of Bacterial Culture in Diagnostics
Are all human pathogens culturable in the lab?
No, many human pathogens are not culturable.
p.12
Types of Culture Media
What is Luria-Bertani broth primarily used for?
It is a complex medium used for growing bacteria.
p.24
Methods for Quantifying Bacterial Growth
What is the relationship between the number of cells in a culture and light transmission?
The more cells in the culture, the more light is scattered, resulting in lower percent of light transmitted.
p.14
Selective and Differential Media
What is the purpose of MacConkey Agar?
To visually distinguish between lactose fermenting strains.
p.5
Classification of Bacteria Based on Carbon and Energy Sources
What do organotrophs use as their electron source?
Electrons from organic compounds (e.g., carbohydrates, lipids, glucose).
p.22
Methods for Quantifying Bacterial Growth
How is bacterial growth quantified on solid media?
By counting the number of colonies.
p.13
Types of Culture Media
What is selective culture media?
Media that allow certain types of organisms to grow while inhibiting the growth of others.
p.8
Oxygen Requirements and Tolerance in Bacteria
What are anaerobic microorganisms?
Microorganisms that do not require oxygen for growth and may even be harmed by it.
p.19
Bacterial Growth Phases and Growth Curves
What are the four characteristic phases of bacterial growth curves?
Lag Phase, Exponential (log) Phase, Stationary Phase, Death Phase.
p.20
Bacterial Growth Phases and Growth Curves
What characterizes the exponential/log phase of bacterial growth?
All cells are dividing regularly and growing at a constant rate as long as nutrients are available.
p.5
Classification of Bacteria Based on Carbon and Energy Sources
What is the difference between photoautotrophs and chemoautotrophs?
Photoautotrophs obtain energy from light, while chemoautotrophs obtain energy from bond breaking.
p.5
Classification of Bacteria Based on Carbon and Energy Sources
Where do plants fall in the classification scheme?
Plants are photoautotrophs.
p.26
Applications of Bacterial Culture in Diagnostics
What is the purpose of the dichotomous key method?
To narrow down possible pathogens through a series of tests on selective/differential media.
p.1
Methods for Quantifying Bacterial Growth
How do we measure bacterial growth?
By quantifying colony-forming units (CFUs), optical density, or cell counts.
p.18
Types of Culture Media
Why is it hard to isolate colonies in liquid culture?
Because cells are evenly suspended and there are no solid surfaces.
p.21
Bacterial Growth Phases and Growth Curves
What occurs during the stationary phase of bacterial growth?
The growth rate and death rate are equal.
p.15
Selective and Differential Media
What is the purpose of MacConkey Agar?
To visually distinguish between lactose fermenting strains.
p.1
Applications of Bacterial Culture in Diagnostics
Where is information about bacterial culture used outside of research?
In clinical diagnostics, food safety, and environmental monitoring.
p.12
Types of Culture Media
What are the main components of Luria-Bertani broth?
10 g tryptone, 10 g NaCl, and 5 g yeast extract.
p.20
Bacterial Growth Phases and Growth Curves
What occurs during the lag phase of bacterial growth?
The population remains temporarily unchanged while adapting to new growth conditions.
p.12
Nutrient Sources for Bacteria
Why is glucose added to M9 salts?
As a carbon source for bacterial growth.
p.14
Applications of Bacterial Culture in Diagnostics
What controls would you use to test an unknown organism for lactose fermentation?
Use a known lactose fermenter and a known non-fermenter as controls.
p.21
Bacterial Growth Phases and Growth Curves
What happens during the death phase of bacterial growth?
The viable cell population declines.
p.3
Temperature and pH Requirements for Bacterial Growth
Why is pH important for bacterial growth?
Different bacteria thrive at different pH levels, affecting their metabolism.
p.8
Oxygen Requirements and Tolerance in Bacteria
What can high concentrations of oxygen produce that is toxic to some microorganisms?
Reactive oxygen species (ROS).
p.13
Types of Culture Media
What is differential culture media?
Media that visually distinguish species based on whether they carry out a specific biochemical reaction.
p.13
Types of Culture Media
What is the primary function of selective media?
To inhibit the growth of unwanted organisms.
p.13
Types of Culture Media
How do differential media help in microbiology?
By allowing visual distinction between species based on biochemical reactions.
p.23
Methods for Quantifying Bacterial Growth
What does each colony on a plate represent?
Each colony represents a cell.
p.18
Types of Culture Media
What is a con of using solid agar?
Limited growth due to contact with the plate.
p.18
Types of Culture Media
What is a benefit of continuous liquid culture?
Allows for larger size and even suspension of cells.
p.14
Selective and Differential Media
What type of bacteria can grow on MacConkey Agar?
Only Gram-negative bacteria.
p.16
Types of Culture Media
What type of media contains a rich mix of nutrients to support a wide variety of bacterial growth?
It is classified as a complex or enriched media.
p.11
Types of Culture Media
What are complex culture media?
Media that contain some ingredients of unknown composition and/or concentration.
p.9
Nutrient Sources for Bacteria
Why do bacteria have diverse nutritional needs?
Due to diverse environments and diverse genetics.
What unique ability do some microorganisms have regarding pH?
They can change the pH of their habitat.
p.10
Types of Culture Media
What do culture media contain?
Required nutrients for microorganisms.
p.1
Bacterial Growth Requirements
What do bacteria need from their environment to grow?
Nutrients, suitable temperature, pH, and oxygen levels.
p.17
Types of Culture Media
How would you classify media that contains a rich mix of nutrients and antibiotics?
Selective only, as it supports growth but selects for antibiotic-resistant organisms.
p.17
Bacterial Growth Requirements
Can all bacterial growth requirements be addressed in the media?
No, temperature cannot be addressed in the media; oxygen can sometimes be addressed.
p.18
Types of Culture Media
What is a benefit of using solid agar for microbial growth?
Allows visualization of colonies and checking for contamination.
p.18
Types of Culture Media
What is the difference between batch and continuous liquid culture?
Batch is closed with limited media; continuous is open with fresh media added continually.
p.12
Types of Culture Media
What are the key components of M9 salts?
12.8 g Na2HPO4-7H2O, 3 g KH2PO4, 0.5 g NaCl, 1.0 g NH4Cl, 2 ml of 1M MgSO4, 20 ml of 20% glucose, and 100 µl of 1M CaCl2.
p.20
Bacterial Growth Phases and Growth Curves
What happens to the cell division rate during the exponential phase?
The cells divide at a constant rate.
p.16
Selective and Differential Media
What type of media contains a rich mix of nutrients to support bacterial growth AND antibiotics?
It is classified as selective media with enrichment.
p.2
Nutrient Sources for Bacteria
What factors are bacteria exposed to that influence their nutritional needs?
Different amounts of nutrients and environmental factors.
p.17
Types of Culture Media
What type of media contains a rich mix of nutrients to support a wide variety of bacterial growth?
Neither selective nor differential.
p.25
Methods for Quantifying Bacterial Growth
What is used to convert OD readings to cell concentration?
A standard curve of optical density.
p.23
Methods for Quantifying Bacterial Growth
How do you calculate the number of cells per milliliter using plate counting?
By counting the colonies and applying the dilution factor.
p.19
Bacterial Growth Phases and Growth Curves
How does a growing bacterial population increase under favorable conditions?
It doubles at regular intervals by geometric progression.
p.24
Methods for Quantifying Bacterial Growth
How does a spectrophotometer work?
It passes a light beam through a bacterial culture to detect the portion of light that passes through.
p.18
Types of Culture Media
What is a con of continuous liquid culture?
No visual indicators for contamination.
p.24
Methods for Quantifying Bacterial Growth
What does a lower percent of light transmitted indicate?
A greater density of the bacterial culture.
p.16
Types of Culture Media
How would you classify a media that contains Xylose as the only carbon source and a pH indicator dye?
It would be classified as a selective media.
p.5
Classification of Bacteria Based on Carbon and Energy Sources
Where do humans fall in the classification scheme?
Humans are chemoheterotrophs.
p.12
Types of Culture Media
What is M9 salts used for?
It is a defined medium for growing bacteria with specific nutrient requirements.
p.16
Bacterial Growth Requirements
Can all bacterial growth requirements be addressed in the media?
No, some specific requirements may not be met.
p.16
Applications of Bacterial Culture in Diagnostics
Are all human pathogens culturable in the lab?
No, not all human pathogens can be cultured.
p.16
Applications of Bacterial Culture in Diagnostics
Do you think all bacteria are culturable?
No, many bacteria cannot be cultured in laboratory conditions.
