Motility of the giant sulfur bacteria
Beggiatoa in the marine environment
Promotionskolloquium
Rita Dunker
15. December 2010
Outline
 General Introduction
 Temperature response of gliding motility in Beggiatoa
 Patterns of gliding motility in Beggiatoa
 Summary & Outlook
1
Introduction
The Genus Beggiatoa
2
Vacuolate sulfur bacteria
(Large marine Beggiatoa,
Thioploca, Thiomargarita)
 -Proteobacteria
Small marine Beggiatoa
 Large, multicellular filaments
Freshwater Beggiatoa
50 µm
 Form mats on soft sediment surface or live
within the sediment
 Oxidize reduced sulfur compounds with
oxygen or nitrate
 Auto- or heterotrophic nutrition
→ Link the S-, N- and C-cycle of
sediments
1 cm
From Teske and Nelson, 2006
 Store elemental sulfur (S0) in the cytoplasm
Introduction
T response
Motility patterns
Summary
3
5 cm
Habitats of Beggiatoa:
Coastal environments:
 Sediments of bays, fjords, inter- and subtidal
zone
 Photosynthetic microbial mats
and deep sea hotspots like
 Seepage areas (cold seeps, mud volcanos..)
 Geothermally active areas
 Whale falls
Image courtesy of Hans Røy © AWI/Ifremer
 Organic material
T response
Motility patterns
Sediments with Beggiatoa occurrence
 Soft sediment
 Opposing gradients of oxygen and sulfide
 Sediment surface if oxygen and sulfide
overlap
Summary
4
Redrawn from Jørgensen et
al. 2010
Introduction
→ Habitats with fluctuating conditions
→ Beggiatoa constantly need to reorient in their
environment
Redrawn from Dunker,
2005
 Suboxic zone if oxygen and sulfide are
separated
T response
Motility patterns
Summary
Motility in Beggiatoa
 Locomotion by slime extrusion
through pores
Oxic
5
From Larkin and Henk, 1996
Introduction
Anoxic
From: Møller et al. 1985
 Tactic responses to chemical and
physical stimuli
Oxic
Anoxic
→ Gliding motility is crucial for the positioning of the filament
in the environment
1 mm
→ Tactic responses provide cues for the directed movement
Introduction
T response
Motility patterns
Beggiatoa mat on the sediment surface
1 cm
1 cm
1 cm
45% air sat.
45%
→ 95% air saturation, 40 h, 30 fps
95% air sat.
Summary
6
Temperature response of gliding motility
Questions
 Does temperature control the gliding speed of Beggiatoa ?
 Is the speed of gliding motility adapted to the prevailing
temperature of different climatic locations?
 What is the acclimatisation potential of gliding speed to changing
temperatures?
7
T response
Motility patterns
Summary
290
 Beggiatoa occur at all climates:
Permanently cold, temperate,
tropical
 Oftentimes seasonally fluctuating
temperatures
 Growth and metabolism are
temperature dependent, how about
gliding motility?
T SWI (K)
Background
18°C
8
Modified after Dale et al.
2008
Introduction
.
280
3°C
275
Minimum
Temperature
Optimum
Temperature
Maximum
Temperature
jan feb mar apr may jun jul aug sep oct nov dec
Annual temperature in 2004
Introduction
T response
Motility patterns
Methods:
 Tropical, temperate and arctic
filaments
 Temperate filaments acclimatized to
summer and winter conditions,
respectively
 Custom-made chamber for monitoring
of gliding speed of single filaments
 Temperature control by a thermostat
Summary
9
Introduction
T response
Motility patterns
Summary
The temperature range for gliding
tropical
temperate
summer
temperate
winter
temperate
arctic
winter
Dunker et al. 2010
temperate
summer
arctic
Motility
Respiration
from Ridgway and Lewin, 1988
tropical
10
Introduction
T response
Motility patterns
Summary
11
Calculation
T range for
of gliding wider
range
for optimal
 that
Range
for optimal
physiological
physiological
activity
activity
Dunker et al. 2010
 T
in situ within
the range for
Activation
energy
optimal physiological activity
Arrhenius
Optimum
T beyond the
equation
range for optimal
a
physiologicalEactivity
ln  ln A 
 Extended T RT
range at winter
conditions
T in situ
T opt
Introduction
T response
Motility patterns
Summary
Response at the extreme ends of the
temperature range
 Filaments withstand transient
freezing
 Decrease in gliding speed at the
cold end is reversible
Arctic filaments
 Decrease in gliding speed at the
warm end is irreversible
Temperate filaments
12
Introduction
T response
Motility patterns
Summary
Conclusions:
 Gliding speed regulated by T
 Gliding is a physiologically regulated response
 Gliding speed is adapted to the prevailing environmental T →
ubiquitous distribution of Beggiatoa
 Acclimatisation to seasonal T changes on a community scale
13
Motility patterns in Beggiatoa
Questions
 Which gliding patterns do Beggiatoa filaments use to orient in their
environment?
 Can these patterns explain the Beggiatoa distribution in the suboxic
zone?
14
Introduction
T response
Motility patterns
Methods
 Filaments in gradient agar tubes
 Imaging setup with illumination and
interval imaging option
 Image analysis
 Monitoring of
Single trails
Changes in gliding direction
Summary
15
Introduction
T response
Motility patterns
Summary
16
Trails of filaments
Within the mat: Filaments „anchor“
at the overlap of oxygen and
sulfide
How?
Dunker et al. submitted
Above and below the mat: Filaments
glide long trails, move a net
distance away from their origin
Introduction
T response
Motility patterns
Summary
17
Reversal patterns of filaments
Within the mat: Average distance is
shorter than filament length
Above and below the mat: Average
distance glided is longer than filament
length
Dunker et al. submitted
Filaments change reversal behaviour when
gliding into the mat
Introduction
T response
Motility patterns
Beggiatoa mat in an oxygen sulfide gradient, 4 h 30 min, 25 fps
Summary
18
Introduction
T response
Motility patterns
Summary
Modeling Beggiatoa motility
Filament in the mat
Filament above and
below the mat
(„random gliding“)
19
Introduction
T response
Motility patterns
Summary
Redrawn from Hinck et al. 2007
Can the model explain the observed Beggiatoa distribution in a
photosynthetic mat with a diurnal migration pattern?
dusk
dawn
20
T response
Motility patterns
10 h dark
cycle
Modeled biomass
distribution
dusk
Summary
Redrawn from Hinck et al. 2007
Introduction
Counted biomass
distribution
dawn
→ 10 h of darkness is not enough to follow the migrating oxygen front
21
Introduction
T response
Motility patterns
Summary
22
Beggiatoa distribution in the suboxic zone
 Most random trails less
than a day
 Long random trails:
NO3- storage is gradually
depleted
Trail duration: several
days
→ High biomass in the
suboxic zone
→ High NO3- storage
capacity needed
NO33-NO
Introduction
T response
Motility patterns
Summary
Conclusion
 Increase of reversal frequency keeps filaments at the oxic-anoxic
interface
 Long random trails can bring filaments back to the oxic-anoxic
interface
 High NO3- storage capacity fuels the long random trails in the anoxic
sediment
 Phobic responses protect the filaments from gliding out of the
suboxic zone
23
Introduction
T response
Motility patterns
Summary
Summary and Outlook
 Beggiatoa gliding speed underlies T control
→ mechanism of gliding?
 Beggiatoa distribution in suboxic zone is in accordance with a phobic
response to sulfide
→ nature of the response to sulfide?
→ role of sulfide in mat formation?
 Reversal behavior
→ coordinated? cell-to-cell communication?
24
Thanks to:
Dr. Dirk de Beer
Prof. Dr. Bo Barker Jørgensen
Dr. Heide Schulz-Vogt
Dr. Hans Røy
Dr. Tim Ferdelman
Technical staff:
Dr. Anja Kamp
Electronic workshop
Dr. Jan Fischer
Mechanic workshop
Associate Prof. Dr. Lars Peter Nielsen (Uni Århus)
Biogeochemistry group
Dr. Peter Stief
Microsensor group
My colleagues from the Biogeochemistry group, family and friends
Thank you for your
attention
T response
Motility patterns
Conclusion
From: Møller et al. 1985
Introduction
Introduction
T response
Motility patterns
Conclusion
Nitrate transport:

H+ translocation ATPase

H+ translocating
pyrophosphatase

NO3-/H+ antiporter
Carbon metabolism:
Vacuole
H+
NO3-
Cytoplasm

Autotrophic or
heterotrophic

Large marine strains:
RubisCO
Sulfur utilisation:
S0

H2S, S0, S2O3-
Poly-phosphate storage as by
genomic data
H2S
SO42-
Introduction
T response
Motility patterns
Conclusion
Model of the gliding mechanism in Myxobacteria
Hydration of electrolyte gel fibers
Gel expands and leaves through
the opening of the pores
Yields enough propulsion force to
explain gliding motility at the
observed speed
Wolgemuth et al. 2002
Introduction
T response
Motility patterns
Conclusion
The temperature range of physiological adaptation
Arrhenius function:
ln  = ln A - Ea/RT
tropical
temperate
summer
Arrhenius plots:
Calculation of the activation
energy Ea
Ea gives an estimate of the T
dependence of a reaction
temperate
winter
arctic
Similar Ea to that of bacterial
enzymatic processes from
cold environments
Introduction
T response
Motility patterns
Tin situ
(°C)
Topt
(°C)
Ea (kJ
mol-1)
Conclusion
Origin of filaments
T response of
gliding speed
Tropical
Mesophilic
20
37
49
2.1 (19-29 °C)
this study
Temperate
Mesophilic
13
30
58
2.3 (12-22 °C)
this study
Temperate (cold
acclimatized)
Mesophilic
4
30
50
2.1 (8-18 °C)
this study
Arctic
Psychrotolerant
6.5
17
46
2.0 (0-10 °C)
this study
Q10
source
Gliding motility of
Beggiatoa alba



35.2

Crozier and Stier,
1926
Gliding motility of
Oscillatoria



38.7

Crozier and
Federighi,
1924
Gliding motility in
Oscillatoria princeps

30-40
42
144a)

Halfen and
Castenholz, 1971
Gliding motility of
Flexibacter polymorphus


35
61.13
2.06 (15-35 °C)
Ridgway and
Lewin, 1988
Respiration of Flexibacter
polymorphus


40
58.62
2.64 (15-35 °C)
Ridgway and
Lewin, 1988
Introduction
T response
Motility patterns
Average distances:
Do individual reversal frequencies
match the mat position?
Within the mat: Filaments glide
shorter distances
Above and below the mat: Filaments
glide longer distances
Conclusion
Introduction
T response
Motility patterns
Motility in Beggiatoa below the
mat- a random walk?
Diffusion coefficient D of a
filament below the mat:
D   L2 / 4 t
L 
D 4t

Filaments without a cue move as by
a random walk
Conclusion
Introduction
T response
Solid line: Distance moved away
from the origin as observed in
a real filament
Dashed line: Distance of a particle
diffusing at the D of a
Beggiatoa filament
Dotted line: Distance moved away
from the origin of a modeled
Beggiatoa filament
Motility patterns
Conclusion
Introduction
T response
Motility patterns
• Nitrate storage: 270 mM
• Nitrate consumption: 13 mM/day → lasts 21 days
Conclusion
Introduction
T response
Motility patterns
Conclusion
Known parameters of coastal sediment
from Århus Bay
Frequency analysis plot:
Most random trails less than a day
Time spend on random trails: on
average 10 days
→ Duration of random trails depends on
NO3- storage
Dunker et al. submitted
Can the model help to explain the distribution pattern of Beggiatoa
in the suboxic zone?
Introduction
T response
Motility patterns
Reversal behavior of Beggiatoa
10 µm
Summary