Microbial Biofilms Quiz
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Questions and Answers

What is the primary advantage of biofilms in microbial communities?

  • Limited access to nutrients
  • Reduced reproduction rates
  • Protection against harmful substances (correct)
  • Enhanced exposure to sunlight

During which phase of biofilm development do microorganisms communicate via quorum sensing?

  • Maturation phase (correct)
  • Dispersal phase
  • Initial colonization phase
  • Attachment phase

What role does extracellular polymeric substance (EPS) play in biofilms?

  • It forms a protective barrier and aids in nutrient retention (correct)
  • It promotes bacterial reproduction exclusively
  • It inhibits the growth of pathogenic species
  • It limits genetic exchange between species

Which of the following best describes the relationship dynamics in biofilms?

<p>Microorganisms may exhibit synergistic and symbiotic relationships (C)</p> Signup and view all the answers

What is the process by which individual bacteria detach from a biofilm to colonize new areas?

<p>Dispersal (D)</p> Signup and view all the answers

What is the primary characteristic of individuals in a reinculture?

<p>They are identical clones. (A)</p> Signup and view all the answers

Which method is NOT used to obtain reincultures?

<p>Spread plate method (B)</p> Signup and view all the answers

What is agar primarily made from?

<p>Complex polysaccharide from red algae. (A)</p> Signup and view all the answers

What do peptones primarily contain?

<p>Hydrolyzed proteins containing elements like C, N, P, and S. (D)</p> Signup and view all the answers

Which kind of media has a known exact chemical composition?

<p>Chemically defined media (C)</p> Signup and view all the answers

Which type of medium supports the growth of a wide range of microorganisms due to its undefined composition?

<p>Complex media (B)</p> Signup and view all the answers

What is one type of extract mentioned that provides a rich source of vitamin B for media?

<p>Yeast extract (D)</p> Signup and view all the answers

Which of the following is not categorized as a type of culture medium?

<p>Cellular media (D)</p> Signup and view all the answers

What is the primary purpose of tryptic soy agar (TSA)?

<p>To provide a rich universal medium for general bacterial growth (D)</p> Signup and view all the answers

Which of the following is a characteristic of selective media?

<p>They contain substances that inhibit the growth of some species. (B)</p> Signup and view all the answers

How does Sabouraud dextrose agar differ from tryptic soy agar?

<p>It has a lower pH, making it selective for certain fungi. (B)</p> Signup and view all the answers

What is the role of enrichment media?

<p>To limit growth to only a few targeted organisms. (A)</p> Signup and view all the answers

Which component in selective media suppresses the growth of gram-positive bacteria?

<p>Crystal violet (B)</p> Signup and view all the answers

Which type of medium allows for visual differentiation between bacterial species?

<p>Differential media (D)</p> Signup and view all the answers

What type of environment does cold enrichment create for targeted bacterial species?

<p>A cold temperature to promote the survival of cold-tolerant species (C)</p> Signup and view all the answers

What is one effect of a pH change in differential media?

<p>It may indicate the consumption of specific substances by bacteria. (A)</p> Signup and view all the answers

What is the primary purpose of quorum sensing in bacteria?

<p>To communicate and coordinate behavior based on population density (C)</p> Signup and view all the answers

Which collection method is used for obtaining cerebrospinal fluid specimens?

<p>Needle aspiration from the subarachnoid space (D)</p> Signup and view all the answers

What is the role of EPS in biofilm formation?

<p>It provides structural support and protection for the microbial community (B)</p> Signup and view all the answers

Which of the following methods can help to prevent biofilm formation?

<p>Blocking receptors with medications (A)</p> Signup and view all the answers

What is an inoculum in the context of culturing microorganisms?

<p>The microorganisms introduced into the growth medium (A)</p> Signup and view all the answers

Which type of specimen collection involves inserting a tube through the nostril into the stomach?

<p>Stomach specimen collection (C)</p> Signup and view all the answers

A pure culture is derived from which of the following?

<p>A single type of cell known as a progenitor (D)</p> Signup and view all the answers

What is the significance of measuring quorum sensing molecules in bacterial communication?

<p>It allows bacteria to adapt their biochemical processes according to the environment (D)</p> Signup and view all the answers

Which of the following is NOT a source of inocula for culturing microorganisms?

<p>Artificially synthesized microorganisms (C)</p> Signup and view all the answers

What is a typical characteristic of a biofilm?

<p>It provides enhanced protection to bacteria against environmental stressors (C)</p> Signup and view all the answers

What indicates whether a bacterium has metabolized a substance when an indicator is added to the medium?

<p>Color change of the indicator (A)</p> Signup and view all the answers

What type of hemolysis is exhibited by Streptococcus pneumoniae in blood agar?

<p>Alpha-hemolysis (A)</p> Signup and view all the answers

What is the role of phenol red in carbohydrate broth media?

<p>Indicator of pH changes (B)</p> Signup and view all the answers

What is a selective property of Mac Conkey agar?

<p>Inhibits the growth of non-lactose fermenters (A)</p> Signup and view all the answers

What makes Mannitol Salt Agar (MSA) selective for staphylococci?

<p>Presence of sodium chloride (D)</p> Signup and view all the answers

What component binds oxygen in anaerobic media?

<p>Cysteine (B)</p> Signup and view all the answers

What is the storage temperature for short-term preservation of cultures in a refrigerator?

<p>4°C (B)</p> Signup and view all the answers

What happens to cultures in anaerobic cabinets?

<p>Oxygen concentration is eliminated (B)</p> Signup and view all the answers

What is the primary method through which most microorganisms reproduce?

<p>Binary fission (D)</p> Signup and view all the answers

Which type of organisms prefer reduced O2 and increased CO2 conditions?

<p>Capnophiles (D)</p> Signup and view all the answers

Flashcards

Symbiotical relationship

A relationship where both organisms benefit from the interaction.

Commensalism

A relationship where one organism benefits while the other is unaffected.

Antagonistic relationship

A relationship where one organism benefits at the expense of another.

Biofilm

A community of microorganisms attached to a surface and encased in a sticky slime layer.

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Biofilm development

The process by which a biofilm develops, involving attachment, growth, communication, and dispersal.

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Quorum Sensing

A process where bacteria communicate with each other using chemical signals.

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Quorum Sensing Molecules

Chemical signals used by bacteria for communication during quorum sensing.

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Cell Density Sensing

The ability of bacteria to detect the concentration of quorum sensing molecules in their environment.

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Quorum Sensing Mechanism

A mechanism where bacteria coordinate their behavior based on cell density.

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Biofilm Inhibition

The process of preventing biofilm formation.

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Culture Medium

A substance that provides nutrients for microbial growth.

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Inoculum

Microorganisms that are introduced into a culture medium.

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Culture

Microorganisms that have grown in a culture medium.

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Pure Culture

A collection of microorganisms originating from a single cell.

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What is a pure culture?

A pure culture contains only one type of microorganism, all derived from a single progenitor cell, also known as a colony forming unit (CFU).

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What is the Streak Plate Method?

The streak plate method involves spreading a bacterial sample across a solid agar plate, gradually diluting the bacteria to isolate individual colonies.

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What is the Pour Plate Method?

The pour plate method involves mixing a bacterial sample with molten agar, then pouring it into a sterile Petri dish. This allows for the separation of bacteria in the agar itself.

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What are culture media?

Culture media or growth media are substances that support the growth of microorganisms in a laboratory setting.

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What is agar?

Agar is a complex polysaccharide derived from the cell walls of red algae, used to solidify culture media.

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What is a defined medium?

Defined media have a precisely known chemical composition, with every ingredient's concentration specified, allowing for specific growth conditions.

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What is a complex medium?

Complex media contain ingredients of unknown chemical composition, such as digests of yeast, meat, or soybeans, making them suitable for a wider range of microorganisms.

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What is a selective medium?

Selective media are designed to inhibit the growth of certain microorganisms while allowing others to grow, enabling isolation of specific species.

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Tryptic Soy Agar (TSA)

A general growth medium suitable for a wide range of microorganisms, providing rich nutrients.

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Complex Culture Medium

A type of culture medium that supports the growth of a wide variety of microorganisms.

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Selective Culture Medium

Growth media that selectively promote the growth of certain organisms while inhibiting others.

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Sabouraud Dextrose Agar

A type of selective culture medium that inhibits the growth of most bacteria, allowing only fungi to grow.

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Enrichment Culture Medium

Culture media designed to promote the growth of a specific type of microorganism while suppressing others.

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Differential Culture Medium

Culture media that allow for visual differentiation between different types of microorganisms based on their growth characteristics.

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Visual Characteristics on a Differential Medium

A visual change in a differential culture medium that helps distinguish between different types of microorganisms.

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pH Change in Differential Medium

A change in the pH of a differential culture medium caused by the metabolic activities of microorganisms.

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Selective media

A type of growth medium that allows for the growth of certain specific types of bacteria but not others.

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Sugar fermentation

The process of bacteria using a specific sugar as a source of energy.

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Differential media

A type of growth medium that allows for the differentiation between bacterial species based on their metabolic products.

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Selective-differential media

A type of growth medium that is both selective and differential, allowing scientists to isolate and differentiate specific types of bacteria based on their metabolic abilities.

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Aerobic media

A growth medium that is specifically designed to suppress the growth of most bacteria while allowing the growth of aerobic bacteria, which can metabolize oxygen.

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Anaerobic media

A growth medium that is designed to support the growth of bacteria that thrive in environments with low oxygen concentrations.

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Sterilization

A technique used to kill all microorganisms on a surface by exposing them to high temperatures.

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Binary fission

The process of bacteria dividing and replicating into two identical daughter cells.

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Microbial growth

The growth of a population of microorganisms, measured as the increase in the number of cells over time.

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Lyophilization

A technique used to preserve microbial cultures for extended periods.

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Study Notes

Microbial Nutrition and Growth (2)

  • Microorganisms live in association with different species in nature.
  • Types of relationships include antagonistic, synergistic, and symbiotic.

Biofilms

  • Biofilms are communities of microorganisms (bacteria and/or fungi) of different species that develop on surfaces.

  • They form a slimy layer that adheres to surfaces like teeth, rocks, and medical devices.

  • Advantages of biofilms include protection against harmful substances/influences, shared nutrients, and exchange of genetic information. Biofilms can also lead to being more pathogenic.

  • The development process of biofilms involves a series of stages: adhesion, multiplication and extracellular polymer substance (EPS) or matrix formation, maturation (communication between microorganisms using quorum sensing) and dispersal.

  • Water currents move among slime layers, allowing efficient access to nutrients and removal of waste products. Individual bacteria or clumps can detach and move to new areas.

  • Quorum sensing is a mechanism by which bacteria communicate with each other using signaling molecules released in the environment. Bacteria measure the concentration of these molecules, which are detected by receptors, to understand the cell density.

  • This allows microorganisms to adjust their biochemistry and shape, as well as coordinate their behavior in response to environmental changes.

Preventing Biofilm Formation

  • Pathogenic microorganisms are often more harmful when part of a biofilm, making it important to find ways to prevent their formation.
  • Strategies include using drugs that block receptors and break down EPS.

Culturing Microorganisms

  • Microorganisms grow using a nutrient medium (nutrient broth) known as growth medium/culture medium.
  • Inoculum refers to the microorganisms being introduced into the medium.
  • Cultures involve both solid and liquid mediums (broth or agar)
  • Different types of media include liquid and solid (nutrient, selective, differential, enrichment).

Types of Culture Media

  • Different types of media support different types of bacteria. Some types of media are used to distinguish between different strains of bacteria.

  • Complex Media: These media have an unknown chemical composition and often include extracts from yeast, meat, or other substances. (e.g., Tryptic Soy Agar - TSA)

  • Selective Media: Contain ingredients that prevent the growth of some microorganisms while allowing others to grow, aiding in isolation. (e.g., selective growth media supporting the growth of gram-negative bacteria)

  • Differential Media: Allow for the visual differentiation of microorganisms based on differences in their metabolic activities or physiological characteristics, aiding in the understanding of species differences. They may contain indicators such as a pH indicator to highlight the result of certain bacterial behaviors. (e.g., MacConkey Agar - MCA)

  • Enrichment Media: Facilitate the growth of a specific microorganism by selectively providing suitable conditions to stimulate its growth while minimizing growth of other organisms

  • Chemical Defined Media: Have known, fixed chemical compositions for accurate and controlled culture situations. (e.g., Specific glucose, phosphate etc., salts in precise fixed quantity)

Microbial Growth

  • Microbial growth mainly occurs through binary fission, where one parent cell divides into two identical daughter cells.
  • Growth stages include replication of DNA, elongation of the cell between attachment sites, formation of a septum, and division of the daughter cells.

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Description

Test your knowledge on microbial biofilms with this quiz focusing on their advantages, development phases, and dynamics. Learn about the critical roles of communication, extracellular polymeric substances, and detachment in biofilm communities. Perfect for microbiology enthusiasts and students!

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