Microbial Biotechnology - General Aspects
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Questions and Answers

What is the primary effect of high glucose concentrations on facultative fermenting microorganisms?

  • Increased oxygen consumption
  • Decrease in oxygen consumption (correct)
  • Induction of the Krebs cycle
  • Enhanced aerobic metabolism
  • At what glucose concentration does S. cerevisiae demonstrate the Crabtree effect?

  • Greater than 50 g/L (correct)
  • Exactly 60 g/L
  • Less than 20 g/L
  • Between 30 and 50 g/L
  • During which phase in the biomass propagation process do cells experience high sugar concentrations?

  • Final fermentation phase
  • Initial batch phase (F2) (correct)
  • Fed-batch phase
  • F1 phase
  • What is necessary to adjust in the fermentor during the biomass propagation process?

    <p>pH to 4.5-5.0</p> Signup and view all the answers

    Which of the following processes is inhibited due to the Crabtree effect?

    <p>Aerobic oxidative processes</p> Signup and view all the answers

    What is one of the main products obtained from microbial biomass?

    <p>Cellular lysates</p> Signup and view all the answers

    Which organism is primarily used in the QuornTM process for protein production?

    <p>Fusarium venenatum</p> Signup and view all the answers

    What ingredients are mixed with the mycoprotein in the QuornTM process for vegan products?

    <p>Potato extract and egg whites</p> Signup and view all the answers

    What type of fermentation process is employed in the production of microbial biomass under controlled conditions?

    <p>Continuous fermentation</p> Signup and view all the answers

    What is a key component of the substrates used in microbial fermentation?

    <p>Simple sugars</p> Signup and view all the answers

    Which mineral salts are commonly included in the substrates for microbial biomass fermentation?

    <p>Potassium, magnesium, and phosphates</p> Signup and view all the answers

    How is the mycoprotein processed after fermentation in the QuornTM production?

    <p>Steamed and frozen</p> Signup and view all the answers

    Which of the following statements about microbial biomass is incorrect?

    <p>It can only produce proteins.</p> Signup and view all the answers

    What phase follows when ethanol is exhausted in the yeast biomass propagation process?

    <p>Fed-batch phase</p> Signup and view all the answers

    Which factor is primarily used to control the growth rate profile during fed-batch cultivation?

    <p>Carbohydrate feedstock feed rate</p> Signup and view all the answers

    What is the optimal pH level to maintain during the fed-batch phase?

    <p>4.5</p> Signup and view all the answers

    Why is controlling the temperature important during fed-batch cultivation?

    <p>To improve biomass yield</p> Signup and view all the answers

    What effect does an increase in the specific growth rate have on biomass productivity?

    <p>Increases biomass productivity</p> Signup and view all the answers

    What is the ideal temperature to maintain during the fed-batch phase?

    <p>30ºC</p> Signup and view all the answers

    Which parameter is NOT critical to optimize biomass productivity during fed-batch cultivation?

    <p>Carbon dioxide emissions</p> Signup and view all the answers

    What is the purpose of optimizing the biomass yield during the fed-batch phase?

    <p>To ensure high-quality biomass</p> Signup and view all the answers

    What are the primary substrates used in yeast production?

    <p>Beet or cane molasses</p> Signup and view all the answers

    Which essential element is mentioned as being poor in molasses?

    <p>Nitrogen</p> Signup and view all the answers

    What sugars are primarily found in molasses?

    <p>Sucrose</p> Signup and view all the answers

    What must be supplemented for fast yeast growth when using molasses?

    <p>Vitamins</p> Signup and view all the answers

    What is the Pasteur effect related to?

    <p>Yeast response to oxygen</p> Signup and view all the answers

    What is a potential negative factor impacting yeast growth from molasses?

    <p>Presence of different toxins</p> Signup and view all the answers

    What process does yeast use to convert sucrose into glucose and fructose?

    <p>Hydrolysis</p> Signup and view all the answers

    Which of the following is not a characteristic of molasses?

    <p>Rich in essential vitamins</p> Signup and view all the answers

    What role does the presence of O2 play in yeast fermentation?

    <p>It helps yeast synthesize lipids.</p> Signup and view all the answers

    Which phase occurs at the beginning of batch fermentation?

    <p>Growth lag phase</p> Signup and view all the answers

    What happens when the sugar concentration drops below a specific level during fermentation?

    <p>A mixed respiro-fermentative metabolism occurs.</p> Signup and view all the answers

    What is a consequence of the Crabtree effect during fermentation?

    <p>Decreased biomass concentration.</p> Signup and view all the answers

    What is one characteristic of the exponential phase in yeast fermentation?

    <p>Cell growth is constant.</p> Signup and view all the answers

    Which phase follows the growth lag phase in batch fermentation?

    <p>Exponential phase</p> Signup and view all the answers

    What is the primary purpose of accumulating reserve metabolites during fermentation?

    <p>To support the subsequent fed-batch phase.</p> Signup and view all the answers

    In what type of metabolism does the alcohol fermentation process generally result?

    <p>Suboptimal biomass concentration.</p> Signup and view all the answers

    What does the fermenting power indicate in the context of Oenological properties?

    <p>The maximum ethanol content produced at the end of fermentation</p> Signup and view all the answers

    Why is high volatile acidity considered undesirable in fermentation?

    <p>It indicates excessive acetic acid production</p> Signup and view all the answers

    Which factor is crucial for achieving optimal fermentation temperature?

    <p>18-28 °C range for optimal fermentation</p> Signup and view all the answers

    What is the implication of selected strains releasing more than 100-400 mg/L of CO2?

    <p>It is considered undesirable in fermentation processes</p> Signup and view all the answers

    What characteristic of a yeast strain is indicated by high fermenting vigor?

    <p>Quick initiation of the fermentation process</p> Signup and view all the answers

    In the context of SO2 tolerance and production, what is a desirable attribute for yeast strains?

    <p>Effective degradation of malic acid</p> Signup and view all the answers

    What outcome does high foam production indicate during fermentation?

    <p>It contributes to frustration in winemaking</p> Signup and view all the answers

    What happens to yeast growth mode during the fermentation process if rapid sedimentation occurs?

    <p>There will be increased dispersed growth during fermentation</p> Signup and view all the answers

    Study Notes

    Microbial Biotechnology - General Aspects

    • Microbial biotechnology has ancient roots, especially in traditional food processing
    • Identifying, selecting, cultivating, and preserving microorganisms (like starters) is fundamental to modern biotechnology
    • A Sumerian clay tablet (c. 4000 BC) documents beer brewing, indicating early microbial use
    • Barley and spelt were ground, soaked, heated, filtered, and fermented with honey and spices to make ancient beer
    • In 1860, Louis Pasteur demonstrated that fermentation is a microbial process, not chemical
    • He showed that yeast can survive and multiply in the presence or absence of oxygen
    • Later in 1883, Emil Christian Hansen used pure yeast cultures to improve beer brewing, a significant advancement
    • The first industrial yeast production was in Austria, 1867
    • In 1872, the first grain yeast factory was founded in France

    Biotechnology Products - Microbial Biomasses

    • Microbial biomass is a readily accessible category of biotechnological product
    • Primary use is for animal feed and human dietary supplements
    • Biomass contains proteins, vitamins, and minerals
    • It can be derived from agro-industrial byproducts or agricultural surplus
    • Various organisms, including bacteria, yeasts, molds, and algae, are sources of biomass, with varying protein content
    • Quorn™ is a protein source alternative to meat, created from a specific fungus (Fusarium venenatum), combined with other nutrients
    • Cellular lysates, enzymes, lipids, nucleic acids, and their derivatives are also extracted from microbial biomass for food and pharmaceuticals

    Biotechnology Products - Primary Metabolites

    • Primary metabolites are crucial for cell growth and reproduction
    • Extracted and purified from the cell into culture media
    • Often result from anaerobic metabolism (e.g., lactic acid from Lactobacillus, propionic acid from Propionibacterium, butyric acid from Clostridium)
    • These compounds are accumulated in significant amounts. Lactobacillus delbrueckii ssp. bulgaricus produced 130 - 140 g L⁻¹ of L-lactic acid
    • Polylactic acid (PLA) - A polymer produced from lactic acid and is thermoplastic, biodegradable, and compostable
    • It is used in various applications including fibers, clothing, and food packaging

    Biotechnology Products - Secondary Metabolites

    • Secondary metabolites have diverse biological activities (e.g., antimicrobials, immunomodulators, antitumor agents)
    • Antibiotics are notable examples of secondary metabolites, often obtained from bacteria or fungi
    • Statins, with cholesterol-lowering activity, are commercially essential secondary metabolites, derived from certain fungi (e.g., Aspergillus terreus, Monascus species)

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    Description

    Explore the fascinating history and fundamental principles of microbial biotechnology. From ancient beer brewing practices in Sumer to Louis Pasteur's discoveries, this quiz highlights key concepts and milestones in the field. Learn about the importance of microorganisms in food processing and biotechnological applications.

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