Unit 4: Biofilms & Motility LECTURE LEARNING GOALS • Describethethreetypesofbacterialbiofilm, and how each develop. • Contrastthedifferentwaysthatmicrobes move using flagella. Explain the ways that bacterial and archaeal flagella are different. Describe non-flagellar movement. • Giveexamplesofhowmicrobesmovefrom the phyla spirochetes and bacteroidetes.

1. BIOFILMS & MOTILITY
Unit 04, 2.11.2021
Reading for today: Brown Ch. 12
Reading for next class: Brown Ch. 22 & 23
Dr. Kristen DeAngelis
Office Hours by appointment
deangelis@microbio.umass.edu
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2. Unit 4: Biofilms & Motility
LECTURE LEARNING GOALS
• Describe the three types of bacterial biofilm,
and how each develop.
• Contrast the different ways that microbes
move using flagella. Explain the ways that
bacterial and archaeal flagella are
different. Describe non-flagellar movement.
• Give examples of how microbes move from
the phyla spirochetes and bacteroidetes.
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3. Unit 4: Biofilms & Motility
LECTURE LEARNING GOALS
• Describe the three types of bacterial biofilm,
and how each develop.
• Contrast the different ways that microbes
move using flagella. Explain the ways that
bacterial and archaeal flagella are
different. Describe non-flagellar movement.
• Give examples of how microbes move from
the phyla spirochetes and bacteroidetes.
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4. Three types of biofilm structure
• Fig. 21.1 Three models of biofilm structure: (A) a monolayer
comprising single cells of one species, (B) a stratified biofilm with
multiple species, and (C) a complex biofilm with three-dimensions of
channels and mushroom-like structures. 4

5. Complex biofilm formation occurs in stages
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6. Three types of biofilm structure
• Five stages of complex biofilm development:
1. Initial attachment,
2. Irreversible attachment,
3. Maturation,
4. Recruitment, and
5. Dispersion.
• Each stage of development in the diagram is
paired with a photomicrograph of a
developing Pseudomonas aeruginosa biofilm.
All photomicrographs are shown to same
scale.
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7. Biofilms form in cycles
• Fig. 21.2 Biofilm formation cycle by which a freely swimming
planktonic cell colonizes a surface and progresses through
biofilm formation; capsule and biofilm matrix material
depicted in light gray around cells and adherent biomass.
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8. Biofilms form in cycles
• Biofilm cycles may be used for
motility, as for this Staphylococcus
aureus biofilm
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9. Biofilm cycles
• Staphylococcus aureus (phylum Firmicutes) is
an opportunistic pathogen that can also
colonize medical devices. It is not always
pathogenic, but it is a common cause of skin
infections (e.g. boils), respiratory disease (e.g.
sinusitis), and food poisoning, complicating
infections by often producing proteinaceous
toxins. Evil cousin is MRSA.
• This is an 11 hour time lapse, rolling caused by
continuous detachment and reattachment in
the direction of flow of the media.
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10. Biofilms are held together by
extracellular polysaccharides (EPS)
• Polymeric sugars are secreted from cells for
hydration, protection and storage
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11. Biofilms are held together by
extracellular polysaccharides (EPS)
• EPS are mostly sugar, but may include
structural proteins, enzymes, nucleic acids,
lipids, and other
• EPS can form a capsule (A) or exist as a
coating of cells as on a grain of feldspar (B)
• EPS has many functions:
– protection from desiccation stress
– protection e.g., biofilm antibiotic resistance
– Attachment
– reserve C source
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12. EPS made by diatoms acts to
stabilizes sediments
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13. EPS made by diatoms acts to
stabilizes sediments
• Metazoans that eat detritus and detritus-
associated microbes (detritivores) ingest and
often digest the EPS along with the microbes
• EPS also affects the environment, in this case
preserving the sediment material that is the
home of diatoms
• Polymers associated with organic material are
so important to soil quality that artificial
polymers are added to soils to retard erosion
and promoter water and nutrient retention
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14. Activity for Review of
Unit 04.1
Draw a picture of how a biofilm “cycles” as a
form of dispersing. Include in your diagram
labels for the five stages of biofilm growth.
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15. Unit 4: Biofilms & Motility
LECTURE LEARNING GOALS
• Describe the three types of bacterial biofilm,
and how each develop.
• Contrast the different ways that microbes
move using flagella. Explain the ways that
bacterial and archaeal flagella are
different. Describe non-flagellar movement.
• Give examples of how microbes move from
the phyla spirochetes and bacteroidetes.
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16. Movement & Orientation
• Flagellar movement
– Chemotaxis
– Phylum Spirochaetes
• Non-flagellar movement
– Gliding motility, Flavobacteria
– Adventurous motility
– Magnetosomes
– Gas vesicles
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17. Bacterial
flagella
Jarrell et al Nat Rev Micro 2008 17
CCW, counterclockwise
CW, clockwise
HAP, hook-associated protein

18. Archaeal flagella
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19. Flagella
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Bacterial flagella Archaeal flagella
consists of three parts: the filament,
the hook and the complex basal
body
Though generally similar, there is no
molecular similarity to bacterial
flagella
When built, extend from the tip When built, extend from the base
Diameter ~20 nm with a central
channel
Diameter ~10 nm with no channel
One type of flagellin Several types of flagellin
Anchored via basal body, rings and
hook
No specific anchoring structure known
Proton gradient across the
cytoplasmic membrane (proton
motive force) drives rotation of the
rotor and the attached filament
ATPase activity drives rotation
Rotate to propel cells for movement Rotate to propel cells for movement

20. Flagellar arrangements
A. Monotrichous
B. Lophotrichous
C. Amphitrichous
D. Peritrichous
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21. Movement & Orientation
• Flagellar movement
– Chemotaxis
– Phylum Spirochaetes
• Non-flagellar movement
– Gliding motility, Flavobacteria (Phylum
Bacteroidetes)
– Adventurous motility
– Magnetosomes
– Gas vesicles
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22. Gliding motility in mycoplasma:
centipede model (L) and inchworm model (R)
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23. Gliding motility in mycoplasma:
centipede model (L) and inchworm model (R)
• Centipede model: Large cell surface Gli proteins
act as ‘legs’ (pink), which are localized in the ‘neck’
region of the cell. The legs attach to the substratum.
ATP hydrolysis in the membrane drives
conformational changes of the legs that result in
cell movement.
• Inchworm model: Adhesins on the surface of the
terminal organelle at the front of the cell (red)
attach to the substratum. Cell movement results
from repeated extension and contraction of the
terminal organelle cytoskeleton (pink), coordinated
with the release of adhesins from the substratum
during the cycle.
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24. Adventurous motility in Myxococcus
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https://www.youtube.com/watch?v=tstc6doiNCU

25. Adventurous motility in Myxococcus
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26. Adventurous motility in Myxococcus
• Polysaccharide secretion model. Polar
secretion and hydration of polysaccharide
propels the cell forward.
• Focal adhesion model. A proposed motor in
the cytoplasm, or cytoplasmic membrane,
interacts with the cytoskeleton and with cell
surface adhesins that are attached to the
substratum. The motor remains fixed with
respect to the adhesins and the substratum
and propels the cell forward.
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27. Magnetosomes
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28. Magnetosomes
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29. Magnetosomes
• "nano-compass" allows the microbe to
passively orient itself in Earth's geomagnetic
field
– high-purity magnetite crystals (Fe3O4)
– up to 3% iron by dry weight
– Biomineralization produces highly uniform
magnetite crystals with narrow size distributions
• Magnetotactic bacteria use magnetosomes
to navigate the oxic-anoxic transition zone
• When they die, magnetosomes become
magnetofossils
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30. Gas vesicles
• Chromatium
okenii is a
microaerobic
sulfide oxidizer
that adjusts its
buoyance with
gas vesicles
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31. Gas vesicles
• hollow, gas-filled cylindrical structures
with conical caps, are composed entirely
from protein and are generally
conserved in morphology throughout
prokaryotes
• used by aerobes to float to oxygenated
surface waters
• consist of a shell of protein with a
hydrophobic inner surface, making it
impermeable to water but permeable to
most gases
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32. Activity for Review of
Unit 04.2
• For each attribute of the flagella, state
whether it is true for bacteria, or
archaea, or both.
___ When built, extend from the tip
___ Diameter ~10 nm with no channel
___ Anchored via basal body, rings and hook
___ ATPase activity drives rotation
___ Rotate to propel cells for movement
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33. Unit 4: Biofilms & Motility
LECTURE LEARNING GOALS
• Describe the three types of bacterial biofilm,
and how each develop.
• Contrast the different ways that microbes
move using flagella. Explain the ways that
bacterial and archaeal flagella are
different. Describe non-flagellar movement.
• Give examples of how microbes move from
the phyla spirochetes and bacteroidetes.
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34. Introducing the Microbial Zoo
• 3 Domains
• 13 Bacterial Phyla,
Archaea,
Eukaryotes and
Acellular life
• Today:
Bacteroidetes and
Spirochaetes
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35. Spirochetes and bacteroids
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36. Phylum Spirochetes
• Phylum Spirochaetae
– Class Spirochetes
• Heterotrophic and tend
to be microaerophilic or
anaerobic
• Saccharolytic (degrade
sugar polymers
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37. Phylum Spirochetes
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• Have polar flagella
that do not emerge
from the outer
membrane of the cell
• Corkscrew
movement provides
propulsive force

38. Borrelia burgdorferi
“the Lyme disease spirochete”
• Phylum Spirochete
• Modes of transmission are
known, but mechanisms for
pathology are not
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39. Phylum Bacteroidetes
• Three classes: Bacteroidia,
Flavobacteria, Sphingobacteria
• Generally saccharolytic anaerobes
(bacteroids) or aerobes
(flavobacteria, sphingobacteria)
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40. Gliding motility in Flavobacterium
• Flavobacterium
gliding is thought
to be powered by
protein motors in
the cell envelope
that propel
adhesins along
the cell surface.
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41. Activity for Review of
Unit 04.3
• Which phylum, Spirochetes, or
Bacteroidetes, or both,
– includes bacteria which have gliding motility?
– includes bacteria that are saccharolytic
heterotrophs?
– includes the causative agent of Lyme
disease?
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42. Unit 4: Biofilms & Motility
LECTURE LEARNING GOALS
• Describe the three types of bacterial biofilm,
and how each develop.
• Contrast the different ways that microbes move
using flagella. Explain the ways that bacterial
and archaeal flagella are different. Describe
non-flagellar movement.
• Give examples of how microbes move from
the phyla spirochetes and bacteroidetes.
Next class is Unit 5: Everything is everywhere...?
Reading for next class: Brown Ch. 22 & 23
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