micro bio day 3 pt 2

Introduction to Biofilms

  • Biofilms can cause various infections:

    • Burn infections

    • Wound infections

    • Respiratory infections

  • Example of albuterol inhaler contamination:

    • Contaminated production line resulted in inhalers with Pseudomonas cells.

    • Patients with chronic respiratory issues inhaled contaminated medication, leading to infection.

Biofilm Formation Stages

1. Initial Attachment

  • Cells attach to a surface.

    • Can involve structures like flagella, fimbriae, or glycocalyx.

    • Attachment is not strong; cells simply land on the surface.

2. Irreversible Attachment

  • Cells begin to attach tightly to each other.

    • Pili, fimbriae, or glycocalyx aid in sticking together.

    • Exopolysaccharide (EPS) production starts, crucial for biofilm development.

    • If washout occurs, biofilm formation is halted.

3. Maturation Stage 1

  • Increased EPS production occurs, leading to:

    • More cell attachment.

    • Cell division within the biofilm.

    • Expansion of the biofilm structure.

4. Maturation Stage 2

  • Continuation of maturation 1.

    • Further EPS production and cell accumulation.

5. Dispersion

  • Free-floating cells leave the biofilm.

    • Offspring of original cells disperse to establish new biofilms elsewhere.

    • Occasionally, chunks of biofilm break off and attach to new surfaces.

Research Example: Yellowstone Hot Springs

  • Researchers study microbes forming thick biomats, displaying multiple colors indicating different microbial layers.

  • Attempts to transfer biomats to other surfaces often disrupt growth.

  • Introduction of sterile surfaces can result in new biofilm formation upon immersion in microbial-rich environments.

Structure and Functions of Attachment Structures

  • Key structures contributing to biofilm formation:

    • Glycocalyx: Provides a protective layer for cells.

    • Pili and fimbriae: Assist in initial attachment and collective stability of cells.

    • Structures can vary by organism, serving either attachment or movement roles.

Introduction to Flagella

  • Flagella are essential for motility in bacteria.

  • Pili and flagella might look similar but serve different functions:

    • Pili: Attachment and adherence.

    • Flagella: Movement and propulsion.

Anatomy of Flagella

  • Flagellum structure includes:

    • M ring: motor functionality, providing rotation.

    • S ring: structural support.

    • P ring: support within the cell wall.

    • Hook: connects filament to the motor.

    • Filament: extends to propel the cell.

Mechanism of Flagellar Motion

  • Entire flagellar structure rotates, not just the filament, enhancing cell propulsion.

    • Torque generated allows efficient movement.

  • Energy input:

    • Requires protons to rotate the motor (3 protons equal one full rotation).

Proton Flow and Energy Generation

  • Proton channels (Mode A and Mode B) facilitate energy transfer for motion through the flagellar motor.

  • Proton influx promotes rotation and thus cell movement, effectively key to bacterial survival.

Differences in Gram-Positive and Gram-Negative Flagella

Structural Variations

  • Gram-positive cells:

    • Present with P ring made of peptidoglycan layer.

  • Gram-negative cells:

    • Additional L ring for lipopolysaccharide structure.

    • Mechanical and functional similarities, but L ring adds an extra layer of durability.

Implications for Motion

  • Loss or damage to any part of the flagellar structure affects motility:

    • M ring failure = no movement.

    • S ring damage = structural compromise.

  • Energy investment in building and maintaining flagella highlights their functional importance.

Conclusion

  • Understanding biofilms and their formation is essential in microbiology and bacterial pathology.

  • Recognizing roles of various structures like flagella, pili, glycocalyx, and EPS is crucial in understanding microbial behavior and infection pathways.

Additional Topics

  • Discussion and exploration of new topics, such as angella and movements related to flagella, to continue in the next session.

robot