Podcast
Questions and Answers
Butyric acid and propionic acid are produced from starch by what process?
Butyric acid and propionic acid are produced from starch by what process?
- Deamination of amino acids
- Decarboxylation of amino acids
- Anaerobic respiration
- Fermentation (correct)
How do bacteria produce indole from tryptophan?
How do bacteria produce indole from tryptophan?
- Anaerobic Respiration
- Decarboxylation of amino acids
- Desulfurization of amino acids
- Deamination of amino acids (correct)
What is the purpose of the Durham tube in a fermentation tube?
What is the purpose of the Durham tube in a fermentation tube?
- To trap any gas produced during fermentation (correct)
- To provide a surface for bacterial growth
- To measure the pH of the medium
- To introduce oxygen into the tube
How do bacteria produce $H_2S$ from cysteine and methionine?
How do bacteria produce $H_2S$ from cysteine and methionine?
What color does phenol red turn in an acidic environment and what approximate pH does this indicate?
What color does phenol red turn in an acidic environment and what approximate pH does this indicate?
In the Methyl Red (MR) test, what color indicates a positive result (large amount of organic acid production, pH below 4.4) after the addition of methyl red?
In the Methyl Red (MR) test, what color indicates a positive result (large amount of organic acid production, pH below 4.4) after the addition of methyl red?
Which type of enzyme functions by breaking down large substrates into smaller components through the addition of water?
Which type of enzyme functions by breaking down large substrates into smaller components through the addition of water?
What is the primary function of amylase?
What is the primary function of amylase?
The MRVP broth is used to distinguish organisms based on what?
The MRVP broth is used to distinguish organisms based on what?
What chemical ratio is characteristic of carbohydrates?
What chemical ratio is characteristic of carbohydrates?
During prolonged incubation, bacteria may start growing on peptone after exhausting the carbohydrate. What effect does this typically have on the pH indicator?
During prolonged incubation, bacteria may start growing on peptone after exhausting the carbohydrate. What effect does this typically have on the pH indicator?
Which of the following is NOT a typical characteristic of monosaccharides?
Which of the following is NOT a typical characteristic of monosaccharides?
Which of the following best describes the purpose of studying microbial metabolism?
Which of the following best describes the purpose of studying microbial metabolism?
Which type of bacteria produce short-chain fatty acids that provide energy for human colonic cells?
Which type of bacteria produce short-chain fatty acids that provide energy for human colonic cells?
What is the term for chemical reactions that release energy from the breakdown of complex organic molecules?
What is the term for chemical reactions that release energy from the breakdown of complex organic molecules?
What are the 'biologic characters' of bacteria, as referenced in the excerpt?
What are the 'biologic characters' of bacteria, as referenced in the excerpt?
What is the primary function of enzymes in metabolic processes?
What is the primary function of enzymes in metabolic processes?
What is the main difference between endoenzymes and exoenzymes?
What is the main difference between endoenzymes and exoenzymes?
Why is metabolism used as a factor to identify bacteria?
Why is metabolism used as a factor to identify bacteria?
What does the study of microbial metabolism help us understand about microbes?
What does the study of microbial metabolism help us understand about microbes?
In the context of the human large intestine, what role does bacterial metabolism play?
In the context of the human large intestine, what role does bacterial metabolism play?
What is the primary function of oxidative catabolism in bacteria?
What is the primary function of oxidative catabolism in bacteria?
What does fermentative catabolism not require?
What does fermentative catabolism not require?
How can you determine whether an organism is oxidative or fermentative?
How can you determine whether an organism is oxidative or fermentative?
What does the yellow color in OF medium indicate?
What does the yellow color in OF medium indicate?
What occurs in the sealed tube of the OF medium if an organism is oxidative?
What occurs in the sealed tube of the OF medium if an organism is oxidative?
What role does bromthymol blue play in the OF medium?
What role does bromthymol blue play in the OF medium?
What is the metabolic end-product of fermentation?
What is the metabolic end-product of fermentation?
What is the purpose of flooding the starch agar plate with Gram's iodine?
What is the purpose of flooding the starch agar plate with Gram's iodine?
Which bacterium is assigned a BSL-2 classification in the procedures?
Which bacterium is assigned a BSL-2 classification in the procedures?
In the context of OF medium, what does dark blue coloration indicate?
In the context of OF medium, what does dark blue coloration indicate?
What technique is essential for inoculating the OF-glucose tubes?
What technique is essential for inoculating the OF-glucose tubes?
Which of the following describes the characteristic of a fermenter in OF medium?
Which of the following describes the characteristic of a fermenter in OF medium?
What type of agar is used in OF medium?
What type of agar is used in OF medium?
What indicates that starch has been hydrolyzed on the starch agar plate?
What indicates that starch has been hydrolyzed on the starch agar plate?
Which of the following bacteria can be used for inoculating the OF-glucose media?
Which of the following bacteria can be used for inoculating the OF-glucose media?
What is the primary incubation temperature for the bacterial plates and tubes during the experiment?
What is the primary incubation temperature for the bacterial plates and tubes during the experiment?
After the first incubation period, how should the plates be stored if they are not examined immediately?
After the first incubation period, how should the plates be stored if they are not examined immediately?
What type of test can be further conducted once a bacterium is determined to be fermentative by the OF test?
What type of test can be further conducted once a bacterium is determined to be fermentative by the OF test?
What addition is made to one OF-glucose tube to create an anaerobic environment?
What addition is made to one OF-glucose tube to create an anaerobic environment?
Which type of starch hydrolysis result indicates that the starch has remained unchanged?
Which type of starch hydrolysis result indicates that the starch has remained unchanged?
Flashcards
Carbohydrate Catabolism
Carbohydrate Catabolism
The biochemical process of breaking down carbohydrates to release energy.
Fermentation
Fermentation
An anaerobic process that converts sugars to acids, gases, or alcohol.
Protein Catabolism
Protein Catabolism
The process of breaking down proteins into amino acids and smaller molecules.
Respiration
Respiration
Metabolic process that produces energy by breaking down glucose with oxygen.
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Metabolism
Metabolism
All the chemical reactions in a living organism necessary for maintaining life.
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Endoenzymes
Endoenzymes
Enzymes that function within a cell to catalyze biochemical reactions.
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Exoenzymes
Exoenzymes
Enzymes secreted outside the cell to catalyze reactions on larger molecules.
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Intestinal bacteria
Intestinal bacteria
Bacteria in the gut that aid digestion and produce metabolites.
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Short-chain fatty acids
Short-chain fatty acids
Fatty acids like butyric and propionic acid produced by bacteria from carbohydrates.
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Fecal odors
Fecal odors
Odors from feces caused by substances like indole and H2S from protein breakdown.
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Amylase
Amylase
An exoenzyme that hydrolyzes starch into smaller carbohydrates.
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Oligosaccharides
Oligosaccharides
Carbohydrates made of 2 to 20 monosaccharides.
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Hydrolysis
Hydrolysis
A chemical reaction involving the addition of water to break down molecules.
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Monosaccharides
Monosaccharides
Simple sugars containing 3 to 7 carbon atoms.
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Polysaccharides
Polysaccharides
Carbohydrates consisting of 20 or more monosaccharide units.
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Fermentation Tubes
Fermentation Tubes
Used to detect acid and gas production from carbohydrates in bacteria.
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Phenol Red Indicator
Phenol Red Indicator
An acid-base indicator that changes color in response to pH alterations during fermentation.
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Methyl Red Test
Methyl Red Test
A test to determine if a bacterium produces a lot of organic acid from glucose, resulting in a red color.
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Voges-Proskauer Test
Voges-Proskauer Test
Used to detect the presence of neutral end products like acetoin, indicated by a color change to yellow.
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Gas Trapping in Durham Tube
Gas Trapping in Durham Tube
This inverted tube traps gas produced during fermentation, indicating microbial activity.
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Oxidative Catabolism
Oxidative Catabolism
The breakdown of glucose in the presence of oxygen, producing CO2 and water.
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Fermentative Catabolism
Fermentative Catabolism
The breakdown of glucose without oxygen, producing organic acids.
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OF Medium
OF Medium
A nutrient agar deep for testing glucose metabolism in bacteria.
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Bromthymol Blue
Bromthymol Blue
A pH indicator in OF medium that turns yellow in acidic conditions.
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Acid Production
Acid Production
Occurs when glucose is metabolized, indicated by color change in OF medium.
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Alkaline Conditions
Alkaline Conditions
Indicated by a dark blue color due to ammonia from peptone use.
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Aerobic Conditions
Aerobic Conditions
Conditions requiring oxygen for bacterial growth and metabolism.
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Anaerobic Conditions
Anaerobic Conditions
Conditions where bacteria grow without the presence of oxygen.
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Metabolic End-Products
Metabolic End-Products
The small organic molecules produced from fermentation.
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Starch Hydrolysis
Starch Hydrolysis
The breakdown of starch into sugars by enzymes produced by microorganisms.
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Gram's Iodine
Gram's Iodine
A reagent used to detect the presence of starch by forming a blue complex.
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OF-Glucose Test
OF-Glucose Test
A test to determine if bacteria can ferment glucose in aerobic or anaerobic conditions.
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Pseudomonas aeruginosa
Pseudomonas aeruginosa
A bacterial species commonly tested for its ability to metabolize sugars.
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Aseptic Technique
Aseptic Technique
Methods used to prevent contamination during microbial procedures.
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Incubation Temperature
Incubation Temperature
The optimal temperature (35°C) for bacteria to grow during tests.
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Bacillus subtilis
Bacillus subtilis
A common soil bacterium used in laboratory exercises.
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Micrococcus luteus
Micrococcus luteus
A yellow-pigmented bacterium used in biochemical testing.
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Starch Agar
Starch Agar
A nutrient medium used to test for starch hydrolysis by bacteria.
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Microbial Metabolism
- Microbial metabolism refers to the chemical reactions within organisms, catalyzed by enzymes
- Early bacterial classification relied solely on morphology
- Biologic characters, including metabolism, are now crucial for classification
- Metabolism includes all reactions within living organisms, primarily involving enzymes inside cells (endoenzymes) or released outside (exoenzymes)
- Enzymes catalyze biochemical reactions
- Studying bacterial metabolism is essential to understand their role in ecology and disease
Carbohydrate Catabolism
- Carbohydrates are a primary source of energy for bacteria
- Catabolism involves breaking down complex carbohydrates into simpler sugars like glucose
- Glucose can be oxidized (using oxygen) or fermented (without oxygen) for energy
- Oxidative catabolism generates CO2 and water, whereas fermentation produces organic acids or other products
- Bacteria can be identified based on their carbohydrate fermentation patterns
Fermentation & Gas Production
- Fermentation is used by some bacteria to generate energy anaerobically from glucose.
- Acidic products are often produced
- Gas production can occur as a byproduct of fermentation
- Gas production can be identified using a tube designed to capture the gas formed.
Differential Media for Microbial Identification
- Differential media are used to distinguish between different types of bacteria based on their metabolic activities
- Example media like Starch Agar or OF-glucose media are used to identify bacteria by their ability to use carbohydrates or to produce acid or gas
- Indicator dyes like bromthymol blue can indicate acidity or alkalinity in growth media
- Specific biochemical tests help identify bacteria based on specific metabolic reactions like producing certain acids or gases
Key Metabolic Processes
- Anaerobic respiration, deamination of amino acids, decarboxylation of amino acids, desulfurization of amino acids are examples of metabolic processes in bacteria
- These processes are crucial for producing energy and for synthesizing components needed by bacteria
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