Lecture 4
? 4.10 Flagella and Motility
? 4.11 Gliding Motility
? 4.12 Bacterial Responses,Chemotaxis,
Phototaxis,and other Taxes
? 4.13 Bacterial Cell Surface Structures
and Cell Inclusions
? 4.14 Gas Vesicles
? 4.15 Endospores
The Flagellum
1000 H+ / rotation
> 40 genes involved
Flagellar motion
? > 40 genes involved,include regulators
? movement driven by propeller-like rotation
? can propel cells up to 60 cell lengths/s
? equivalent of 2.5x faster than a cheetah!
? expensive process,must confer strong
selective advantage
Steps in Biosynthesis of Flagella
Run
Types of Flagellar Arrangements
Motility in non-aqueous
environments
1,polysaccharide,slime layer”
— secreted slime used to pull cell along a
surface
2,special proteins in the outer membrane act
like feet,which are activated by inner
membrane proteins resulting in,crawling”
Absence of chemical attractant
Fig,4.46a
Presence of chemical attractant
Fig,4.46b chemical gradient sensed in a temporal manner
Measuring Chemotaxis
control repellent
attractant
Other types of taxes
? phototaxis - light
? aerotaxis - oxygen
? osmotaxis - osmotic strength
Cell structures and inclusions
? fimbriae - aid cell adherence to surfaces
? pili - conjugation,attachment to host cell
? glycocalyx - polysaccharide layer outside cell,attachment to host cells,
protection from host immune system,resistance to dessication
? polyhydroxyalkanoate deposits - intracellular carbon and energy
store
? polyphosphate - intracellular reserves
? elemental sulfur - intracellular granules
? magnetosomes - intracellular magnetite crystals (iron oxide)
? gas vesicles - cell buoyancy
Poly-?-hydroxybutyrate (PHB)
Poly-3-hydroxybutyrate
(PHB)
?Carbon and energy reserve
?Accumulates intracellularly when carbon
source is not limiting for growth
?Can be utilized under carbon starvation
conditions
?Biodegradable bioplastics
?Production does not contribute greenhouse
gases
CH3
— O·CH·CH2·C —
O[ ]
n ~ 25,000
Gas Vesicle Proteins
Fig,4.58
watertight,gas-permeable structure
(hydrophobic proteins)
Endospores
Fig,4.62
Resistant to heat,radiation,acids,drying,chemicals
Do not contain RNA
Dehydrated (only 10-30% H2O as vegetative cell)
T abl e 3.2 Differences b et w een end o sp o res an d
v eg etati v e cells
Ch ara cter i stic Veg etati v e cell En d o spo re
Microsco pi c
appear ance
Non r efract il e Refractil e
Cal ci um c onten t Lo w High
Dip ic ol in ic ac id Lo w High
Enz y m atic
activit y
High Lo w
Metabo li sm (O
2
uptake)
Present Lo w or a bse nt
Macromol ecu la r
s y nt hesi s
Present Absent
mRNA Present Lo w or a bse nt
Hea t resista nce Lo w High
Rad ia tio n
resistanc e
Lo w High
Resista nce to
chemic al s an d
acid s
Lo w High
St ai na bi l it y b y
d y es
St ai na bl e St ai na bl e only
w it h spec ia l
methods
Act io n of
l y s oz y me
Sensitiv e Resista nt
W ater c onten t High,80-9 0% Lo w,10- 25 %
Small ac id
solu bl e pr otei ns
Absent Present
C y to pl asmic pH ~7 5.5-6.0
Dipicolinic acid
Fig,4.61
Characteristic of endospores
How long can spores survive?
? See page 97,report that 250 million year
old spores have been revived
? These spores were preserved in salt crystals
of Permian age
? bacteria revived from brine deposits
? environmental contaminants prevented by
steriliziation; controls for sterility
Endospore Formation
? triggered by sub-optimal growth conditions
(heat,starvation,dessication,etc.)
? return to optimal conditions sees
germination of spores within minutes
? studied by isolating mutants that do not
form spores and studying at what point
sporulation is blocked
Sporulation
Initiated when
nutrients
limiting
Stages determined
by mutational
analysis
~200 genes involved
SASP = small acid-soluble spore proteins
Cortex is composed of peptidoglycan
Exosporium is a thin protein covering
8 h for entire process
? 4.10 Flagella and Motility
? 4.11 Gliding Motility
? 4.12 Bacterial Responses,Chemotaxis,
Phototaxis,and other Taxes
? 4.13 Bacterial Cell Surface Structures
and Cell Inclusions
? 4.14 Gas Vesicles
? 4.15 Endospores
The Flagellum
1000 H+ / rotation
> 40 genes involved
Flagellar motion
? > 40 genes involved,include regulators
? movement driven by propeller-like rotation
? can propel cells up to 60 cell lengths/s
? equivalent of 2.5x faster than a cheetah!
? expensive process,must confer strong
selective advantage
Steps in Biosynthesis of Flagella
Run
Types of Flagellar Arrangements
Motility in non-aqueous
environments
1,polysaccharide,slime layer”
— secreted slime used to pull cell along a
surface
2,special proteins in the outer membrane act
like feet,which are activated by inner
membrane proteins resulting in,crawling”
Absence of chemical attractant
Fig,4.46a
Presence of chemical attractant
Fig,4.46b chemical gradient sensed in a temporal manner
Measuring Chemotaxis
control repellent
attractant
Other types of taxes
? phototaxis - light
? aerotaxis - oxygen
? osmotaxis - osmotic strength
Cell structures and inclusions
? fimbriae - aid cell adherence to surfaces
? pili - conjugation,attachment to host cell
? glycocalyx - polysaccharide layer outside cell,attachment to host cells,
protection from host immune system,resistance to dessication
? polyhydroxyalkanoate deposits - intracellular carbon and energy
store
? polyphosphate - intracellular reserves
? elemental sulfur - intracellular granules
? magnetosomes - intracellular magnetite crystals (iron oxide)
? gas vesicles - cell buoyancy
Poly-?-hydroxybutyrate (PHB)
Poly-3-hydroxybutyrate
(PHB)
?Carbon and energy reserve
?Accumulates intracellularly when carbon
source is not limiting for growth
?Can be utilized under carbon starvation
conditions
?Biodegradable bioplastics
?Production does not contribute greenhouse
gases
CH3
— O·CH·CH2·C —
O[ ]
n ~ 25,000
Gas Vesicle Proteins
Fig,4.58
watertight,gas-permeable structure
(hydrophobic proteins)
Endospores
Fig,4.62
Resistant to heat,radiation,acids,drying,chemicals
Do not contain RNA
Dehydrated (only 10-30% H2O as vegetative cell)
T abl e 3.2 Differences b et w een end o sp o res an d
v eg etati v e cells
Ch ara cter i stic Veg etati v e cell En d o spo re
Microsco pi c
appear ance
Non r efract il e Refractil e
Cal ci um c onten t Lo w High
Dip ic ol in ic ac id Lo w High
Enz y m atic
activit y
High Lo w
Metabo li sm (O
2
uptake)
Present Lo w or a bse nt
Macromol ecu la r
s y nt hesi s
Present Absent
mRNA Present Lo w or a bse nt
Hea t resista nce Lo w High
Rad ia tio n
resistanc e
Lo w High
Resista nce to
chemic al s an d
acid s
Lo w High
St ai na bi l it y b y
d y es
St ai na bl e St ai na bl e only
w it h spec ia l
methods
Act io n of
l y s oz y me
Sensitiv e Resista nt
W ater c onten t High,80-9 0% Lo w,10- 25 %
Small ac id
solu bl e pr otei ns
Absent Present
C y to pl asmic pH ~7 5.5-6.0
Dipicolinic acid
Fig,4.61
Characteristic of endospores
How long can spores survive?
? See page 97,report that 250 million year
old spores have been revived
? These spores were preserved in salt crystals
of Permian age
? bacteria revived from brine deposits
? environmental contaminants prevented by
steriliziation; controls for sterility
Endospore Formation
? triggered by sub-optimal growth conditions
(heat,starvation,dessication,etc.)
? return to optimal conditions sees
germination of spores within minutes
? studied by isolating mutants that do not
form spores and studying at what point
sporulation is blocked
Sporulation
Initiated when
nutrients
limiting
Stages determined
by mutational
analysis
~200 genes involved
SASP = small acid-soluble spore proteins
Cortex is composed of peptidoglycan
Exosporium is a thin protein covering
8 h for entire process
