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.