Test 1 Flashcards
Biofilm
community of microO working together
16S rRNA Genes
Used to create 3 domain classification, small ribosomal subunit
Microbiologists study…
Cellular, ie fungi, protists, bacteria, archaea
Acellular, ie viruses, viroids, virusoids, prions
We will study…
Bacteria, Archaea, Viruses, Viroids, Virusoids, Prions
Microbiology prompted creation of…
immunology
Antony van Leeuwenhoek (1632-1723)
First person to observe and describe microO accurately, aided in development of microscope
Spontaneous generation
living organisms can develop from nonliving or decomposing matter, popular up to 1600s
Francesco Redi (1626-1697)
disproved spontaneous generation for large animals, maggots on decaying meats from fly eggs
John Needham (1713-1781)
mutton broth -> boiled -> sealed = microO
concluded -> “vital force”
Lazzaro Spallanzani (1729-1799)
broth -> sealed -> boiled = no microO
concluded -> air carries germs
BUT maybe air supports life
Louis Pasteur (1822-1895)
Nutrient soln in flasks w/ curved necks -> boiled -> exposed to air
Disproved spontaneous generation
John Tyndall (1820-1893)
dust carries microO, sterile broth -> one neck of flask broken, other not -> broken neck growth occurs
Microbes causative in disease?
diverse evidence:
1) Agostini Bassi (1773-1856)
• disease of silkworms was caused by a fungus
2) M. J. Berkeley (ca. 1845)
• Great Potato Blight of Ireland caused by a fungus
3) Heinrich de Bary (1853)
• smut and rust fungi => cereal crop diseases
4) Louis Pasteur
• silkworm disease caused by a protozoan
Joesph Lister (1827-1912)
indirect evidence for microO cause of disease, antiseptic surgical techniques, heat sterilization/phenol lessen # infections
Thomas Eakins
Gross Clinic Painting
Agnew Clinic
Robert Koch (1843-1910)
est. relationship between B. anthracis and anthrax; used criteria developed by Jacob Henle:
injected healthy w/ material from sick
sick spleen into culture
spores into healthy mice
Now known as Koch’s Postulates
Koch’s Postulates
To prove a causal relationship between microorg. & disease:
- The microorganism must be present in every case of the disease but absent from healthy individuals
- The suspected microorganism must be isolated and grown in a pure culture
- The same disease must result when the isolated microorganism is inoculated into a healthy host
- The same microorganism must be isolated again from the diseased host
Koch’s work led to…
agar, petri dish, nutrient broth and agar, methods for isolating microO
Increased understanding of pathogens
Edward Jenner (~1798)
vaccination procedure to protect individuals from smallpox, preceded work est. role of microO in disease
Pasteur and Roux
incubation of cultures for long intervals, pathogens lost ability to cause disease “attenuated”
Transfer to healthy host protection against infection
Pasteur and coworkers
vaccines for chicken cholera, anthrax, and rabies
Emil von Behring (1854-1917) and Shibasaburo Kitasato (1852-1931)
Inactivated diphtheria toxin into rabbits, produced transferable antitoxin
developed antitoxins for diphtheria and tetanus
evidence for immunity from “soluble substances” in blood (humoral immunity)
Elie Metchnikoff (1845-1916)
discovered bacteria-engulfing, phagocytic cells in the blood, (cellular immunity)
Sergei Winogradsky (1856-1953) and Martinus Beijerinck (1851-1931)
pioneered use of enrichment cultures, selective media
soil microO
numerous interesting metabolic processes
Microbiology as a basic science…
basic biology of microO
understanding microO improved understanding of other Os
Microbiology as an applied science…
medical microbio, immunology, food and dairy microbio, pub health microbio, industrial microbio, agricultural microbio
Future of Micriobiology…
new and old infectious diseases, industrial processes, diversity and ecology, biofilms, genome analysis, microbes as model systems
Magnification
increases apparent size of specimen, calculated by multiplying magnification factors of lenses
Resolution
minimum distance that two objects can be separated from one another, and still be recognized as distinct objects rather than 1 larger “fuzzy” object
Increasing Resolution
oil: higher refractive index than air
decreasing illumination wavelength
focusing illumination light (condenser)
Illumination: Brightfield
Method of lighting the specimen from opposite the objective
appears dark against a light background
common method
usually need staining
Illumination: Darkfield
illuminationof the specimen w/o projecting light directly into the objective
used to examine specimens which cannot be distinguished from the background
unstained, living
Fixation
preservation of internal and external structures
organism is killed and firmly attached to microscope slide
heat fixing and chemical fixing
Heat fixing
preserves overall morphology (not internal structures)
Chemical fixing
protects fine cellular substructure and morphology of larger, more delicate organisms
Dyes
make cell structures more visible
increased contrast w/ background
chromophore groups + ability to bind cells
Basic dyes
positively charged
Acidic dyes
negatively charged
simple staining
single staining agent
frequently basic dyes
crystal violet; methylene blue
Differential stains
divides microO into groups based on their staining properties
gram stain
acid-fast
staining of specific structures
Gram Staining
most widely used Gm+, Gm- primary stain, crystal violet mordant, gram's iodine decolorization, etoh counterstain, safranin Gm+ Purple GM- Pink
Acid Fast staining
staining for members of genus Mycobacterium
M. tuberculosis
M. leprae
high lipid content in cell walls
Negative Staining
visualize capsules, colorless against a stained background
Spore Staining
Double staining technique
bacterial endospore vs vegetative cell
Flagellar Staining
Mordant to increase thickness
Phase-contrast light microscopy
visualizing living cells
no stain
Transmission electron microscopy
Much like brightfield, electron stream opposite to specimen
Scanning electron microscopy
More like darkfield, visualize outside of specimen
cocci (s., coccus)
Spheres
diplococci (s., diplococcus)
Pairs
streptococci
Chains of spheres
staphylococci
grape-like clusters of spheres
tetrads
4 cocci in a square
sarcinae
cubic configuration of 8 cocci
bacilli (s., bacillus)
rods
coccobacilli
very short rods
vibrios
“comma” shaped
spirilla (s., spirillum)
rigid helices
spirochetes
flexible helices
filamentous
form hyphae
mycelium
branched hyphae
unusual shapes
archaea
Bacterial cell envelope
plasma membrane + surrounding layers
Bacterial plasma membrane
separation of cell from its environment selectively permeable crucial metabolic processes - respiration, lipid synthesis, (some) photosynthesis membrane receptors ex. phosphatidylenthanolamine + hopanol
Bacterial cell wall
shape protection may contribute to pathogenicity may protect from toxic substances Peptidoglycan aka murein
Periplasmic space
gap between plasma membrane and cell wall in Gm+ or between plasma membrane and OM in Gm-
periplasmic + exoenzymes
Periplasmic enzymes
periplasm of Gm- nutrient aquisition electron transport peptidoglycan synthesis modification of toxic compounds
Exoenzymes
secreted by Gm+ bacteria
similar functions to periplasmic enzymes
Cell Wall and osmotic protection
osmotic lysis - hypertonic solns, cell wall protects
plasmolysis - hypertonic solns, cell wall can’t protect
Bacterial cell wall and Gram staining
thought to involve constriction of the thick peptidoglycan layer of gram positive cells
Thinner peptidoglycan layer of gram-negative bacteria does not prevent loss of crystal violet
Bacterial cell wall structure: peptidoglycan
polysaccharide formed from peptidoglycan subunits
backbone: alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
most Gm- walls z shaped bridge
most Gm+ walls pentaglycine bridge
Helical cross linking for strength
Gram-positive cell envelope
No OM
Cell wall primarily peptidoglycan may also contain teichoic acids
lipoteichoic acid anchors to PM
Some Gm+ bacteria has layer of proteins on surface of peptidoglycan
Gram-negative cell envelope
OM: lipids, lipoproteins, and lipopolysaccharide (LPS) no teichoic acids
cell wall: thin peptidoglycan layer surrounded by OM
Gm- cell envelope: Braun’s lipoproteins
connect OM w/ peptidoglycan
Gm- cell envelope: adhesion sites
direct contact between plasma membrane and OM, may allow direct movement of material into cell
Gm- cell envelope: lipopolysaccharides (LPS)
O antigen: protection from host defenses, immunogenic
core polysaccharide: contributes to negative charge on cell surface
lipid A: helps stabilize OM structure, can act as an exotoxin
exotoxin
pathogenic when released, by death or cleavage
endotoxin
intact bacteria is pathogenic
Gm- cell envelope: OM
protective membrane
more permeable than plasma membrane
presence of porins and transporters
Layers outside the cell wall
Typically pathogenic have these Capsules, Slime Layers, S-layers protection from host defenses protection from harsh environmental conditions attachment to surfaces protection from viral infection or predation by bacteria protection from chemicals in environment motility protection against osmotic stress
Capsules
usually polysaccharides
well organized; not easily removed
resist phagocytosis
Slime layers
polysaccharides
diffuse, unorganized; easily removed
S-layers
structured layers of protein or glycoprotein
common in Archaea
glycocalyx
eukaryotes
polysaccharide network
like capsule/slime layer
Archaeal cell envelope
different from bacterial both molecularly and organizationally
methanochondroitin = cell wall like
pseudomurein
Archaeal Plasma membrane
composed of unique lipids
some have monolayer
some bilayer
Archaeal Cell Wall
Gm stain not useful
lack peptidoglycan
The cytoplasmic matrix
substance between membrane and nucleoid
packed with ribosomes and inclusion bodies
highly organized; cytoskeleton-like organization/function
Bacterial cytoskeleton
homologs of eukaryotic cytoskeleton components have been identified.
Tubulin homologs
FtsZ - cell division
BtubA/BtubB - unknown
Actin homologs
FtsA - cell division
MamK - positioning magnetosomes
MreB/Mbl - maintains cell shape, segregates chromosomes, localizes proteins
Intermediate Filament homologs
CreS (crescentin) - induces curvature in curved rods
Unique bacterial cytoskeletal proteins
MinD
ParA
Bacterial intracytoplasmic membranes
plasma membrane infoldings
anammoxosome
plasma membrane in-foldings
found in many photosynthetic bacteria, and bacteria with high respiratory activity
may be aggregates of spherical vesicles, flattened vesicles, tubular membranes
anammoxosome
membrane-bound organelle
anaerobic ammonia oxidation
unique to Planctomycetes
inclusion
aggregation of organic or inorganic material
storage inclusions
microcompartments
other inclusions
Storage Inclusions: Carbon
glycogen inclusions
poly-beta-hydroxybutyrate inclusions
Storage Inclusions: phosphate
polyphosphate granules
Storage Inclusions: sulfur
sulfur globules
Storage inclusions: nitrogen
Cyanophycin granules
cyanobacteria
large polypeptides not from ribosomes, equal quantities of arg and asp
Microcompartments: carboxysomes
function other than metabolic stockpile
cyanobacteria, CO2 fixing
Concentration of CO2; enzyme localization
ribulose-1,5-bisphosphate carboxylase (RUBISCO) fixes carbon in calvin cycle
Other inclusions: gas vacuoles
some aquatic prokaryotes
provides buoyancy
aggregates of gas vesicles
hollow cylindrical structures
Other inclusions: magnetosomes
contain iron
used to orient cells in magnetic fields
Prokaryotic Ribosomes
complexes of protein and RNA sites of protein synthesis associated w/ plasma membrane - secrete matrix ribosomes - internal smaller than eukaryotic ribosomes 70S = large 50s + small 30s
Nucleoid
aka nuclear body, chromatin body, nuclear region
~60% DNA 30% RNA 10% Protein
location of chromosome, usually 1/cell often circular
nucleoid proteins probably aid in folding, differ from histones
Plasmids
usually small, closed circular DNA
extrachromosomal
not required for growth and reproduction
can be laterally transferred
External Structures: Fimbriae
short, thin, hairlike, proteinaceous appendages
up to 1000/cell
mediate attachment to surfaces
type IV fimbriae: twitching motility in some bacteria
External structures: sex pili
similar to fimbriae
except longer, thicker, and less numerous 1-10/cell
required for mating
Bacterial flagella
used by most motile bacteria
thin, rigid structures
patterns of arrangement
polar
flagellum at end of cell
monotrichous
one flagellum
amphitrichous
one flagellum at each end of cell
lophotrichous
cluster of flagella at one or both ends
peritrichous
spread over entire surface of cell
Bacterial flagella: ultrastructure
filament
hook
basal body
Bacterial flagella: filament
hollow, rigid cylinder
flagellin subunits
Bacterial flagella: hook
links filament to basal body
Bacterial flagella: basal body
series of rings that drive flagellar motor
Bacterial flagella synthesis
self-assembly
flagellin transported through hollow filament, similar to type III secretion
growth from tip, not base
Bacterial flagella movement
flagellum rotates like a propeller CCW - forward motion (run) CW - disrupts run (tumble) Motor on bottom, bearings on top Powered by proton gradient from ETC MotA and MotB make channel to turn Exergonic rxn
Archaeal Flagella
Analogous function, different structure more than one flagellar subunit type not hollow; thinner hook/basal body rotation CCW pulls cell CW pushes cell
Motility
Flagellar Movement
Spirochete motility
Twitching motility
Gliding motility
spirochete motility
periplamic axial fibrils (bundles of flagellum): flexing/spinning movement
movement kind of like a screw
twitching motility
pili (type IV) involved
observed in groups of cells (contacting)
gliding motility
coasting along solid surfaces
no known visible motility structure
cyanobacteria, myxobacteria, etc
Myxococcus xanthus gliding; polysaccaride secretion or adhesion complexes
Chemotaxis
movement towards a chemical attractant or away from a chemical repellant
detected by cell surface receptors
Absence of chemoattractant
random movement
about same number of tumbles and runs
Present chemoattractant
directional movement
caused by lowering the frequency of tumbles
longer runs when chemoattractant sensed inc. in concentration
when conc. stops inc. number of tumbles inc.
Bacterial Endospore
formed by some Gm+ bacteria
dormant; resistant to numerous environmental conditions
Spore positions
Central
Subterminal
Terminal
Swollen sporangium
Spore Structure
exosporium (thin)
spore coat (thick) impermiable; chem. resistance
Cortex; peptidoglycan
Core wall; derived from plasma membrane, surrounds protoplast
Protoplast; nucleoids, ribosomes, inactive
What makes an endospore so resistant?
not totally understood, but…
calcium (complexed with dipicolinic acid)
small, acid soluble, DNA binding proteins (SASPs)
dehydrated core
spore coat
DNA repair enzymes
Sporulation
commences when growth ceases, lack of nutrients complex multistage process 1. cell division 2. plasma membrane pinches off cell into two areas 3. cell dies 4. cortex forms 5. spore finishes 6. vegetative cell falls away
Transformation of spore to vegetative cell
- activation; prepares spore for germination
- germination; spore swelling, rupture/absorption of spore coat, loss of resistance, increased metabolic activity
- Outgrowth; emergence of vegetative cell
Common Nutrient Requirements
Macroelements
Micronutrients
Macroelements
most cell dry weight:
C H O N S P
K+ Ca2+ Mg2+ Fe2+/3+
Required in relatively large amounts
Micronutrients
trace elements
Mn Zn Co Mo Ni Cu
enzyme cofactors
often supplied in water or media components
Carbon, Hydrogen, Oxygen, electrons
need often satisfied together
carbon source often provides H, O and electrons
C/H/O: biosynthesis
electrons: energy + reduction during biosynthesis
Autotrophs
CO2 sole or principal biosynthetic carbon source
Heterotrophs
reduced, preformed, organic molecules from other organisms
Phototrophs
light as energy source
Chemotrophs
oxidation of organic or inorganic compounds as energy source
Lithotrophs
electrons from reduced inorganic molecules
Organotrophs
electrons from organic molecules
Majority of microO studied…
photoautotrophs + chemoheterotrophs
Most pathogens…
chemoheterotrophs
Photoorganoheterotrophs
polluted lakes
Chemolithoautotrophs
oxidation of reduced inorganic compounds
Chemolithoheterotrophs
important in nutrient cycling in ecosystems
mixotroph
can use multiple metabolic strategies
Requirements for nitrogen, phosphorus, and sulfur
needed for synthesis of key molecules
nitrogen; organic molecules, ammonia, nitrogen gas
phosphorus; inorganic phosphate
sulfur; sulfate via assimilatory sulfate reduction
Growth Factors
essential cell components; cells can't synthesize must be supplied by environment AA's purines and pyrimidines vitamins - enzyme cofactors
Growth-response assay
measure concentrations of growth factors in a preparation
comparison of known to std. curve
Industrial fermentation
production of vitamins by microO
vit B12, C
Uptake of nutrients
passive diffusion
facilitated diffusion
active transport
iron uptake
Passive diffusion
High to low concentration
non-polar molecules
Water, O2 CO2
Facilitated diffusion
similar to passive, not E dependent, high to low conc. size of gradient impacts uptake rate Carrier molecules smaller conc. gradient required transport of glycerol, sugars, AA's more prominent in eukaryotic cells Carrier saturation effect
Active Transport
Against conc. gradient E dependent - ATP or proton motive force Conc. molecules inside of cell Requires carrier proteins (Carrier Sat. effect) ABC transporters group translocation
ATP Binding Cassette (ABC) transporters
conserved in all three domains
pore: 2 TM domains, nucleotide binding domains (ATP)
substrate binding protein; in periplasm, deliver molecule to transporter
sugars
AAs
certain antibiotics
Group Translocation
molecules modified during transport, energy dependent
ex. sugar phosphotransferase system (PTS)
widely distributed in bacteria, many faculative anaerobes, not in most aerobes
Phosphoenolpyruvate: sugar phosphotransferase system (PTS)
transport of many carbohydrates
PEP phosphorylates enzyme 1 phosphorylates heat-stable protein (HPr) phosphorylates enzyme IIA, IIB, for transport
Energy for active transport
ATP hydrolysis
H+ gradients from electron transport; direct energy, indirect energy
H+ gradients: direct energy
lactose permease (symporter), facilitative diffusion Na/H+ exchanger (antiporter)
H+ gradients: indirect energy
Na+ symporter, indirectly powered by proton motive force Na from Na/H+ exchanger
Iron Uptake
ferric iron (Fe3+) insoluble; uptake difficult
siderophores
aid uptake of Fe3+ enterobactin secreted; complexes with Fe3+ complex transported In Gm- complex bound by receptor OM periplasm: either Fe3+ released or complex transported via ABC
Getting things through the Gm- OM
small molecules - generalized porins
large molecules - specialized porins
Specific carriers - iron uptake
Culture media
preparations that support growth
can be liquid or solid
solidify with agar
polar
flagellum at end of cell
monotrichous
one flagellum
amphitrichous
one flagellum at each end of cell
lophotrichous
cluster of flagella at one or both ends
peritrichous
spread over entire surface of cell
Bacterial flagella: ultrastructure
filament
hook
basal body
Biofilm
community of microO working together
Bacterial flagella: filament
hollow, rigid cylinder
flagellin subunits
Bacterial flagella: hook
links filament to basal body
Bacterial flagella: basal body
series of rings that drive flagellar motor
Biofilm
community of microO working together
Bacterial flagella synthesis
self-assembly
flagellin transported through hollow filament, similar to type III secretion
growth from tip, not base
Bacterial flagella movement
flagellum rotates like a propeller CCW - forward motion (run) CW - disrupts run (tumble) Motor on bottom, bearings on top Powered by proton gradient from ETC MotA and MotB make channel to turn Exergonic rxn
Archaeal Flagella
Analogous function, different structure more than one flagellar subunit type not hollow; thinner hook/basal body rotation CCW pulls cell CW pushes cell
Biofilm
community of microO working together
Motility
Flagellar Movement
Spirochete motility
Twitching motility
Gliding motility
spirochete motility
periplamic axial fibrils (bundles of flagellum): flexing/spinning movement
movement kind of like a screw
twitching motility
pili (type IV) involved
observed in groups of cells (contacting)
gliding motility
coasting along solid surfaces
no known visible motility structure
cyanobacteria, myxobacteria, etc
Myxococcus xanthus gliding; polysaccaride secretion or adhesion complexes
Biofilm
community of microO working together
Chemotaxis
movement towards a chemical attractant or away from a chemical repellant
detected by cell surface receptors
Absence of chemoattractant
random movement
about same number of tumbles and runs
Present chemoattractant
directional movement
caused by lowering the frequency of tumbles
longer runs when chemoattractant sensed inc. in concentration
when conc. stops inc. number of tumbles inc.
Bacterial Endospore
formed by some Gm+ bacteria
dormant; resistant to numerous environmental conditions
Spore positions
Central
Subterminal
Terminal
Swollen sporangium
Spore Structure
exosporium (thin)
spore coat (thick) impermiable; chem. resistance
Cortex; peptidoglycan
Core wall; derived from plasma membrane, surrounds protoplast
Protoplast; nucleoids, ribosomes, inactive
Biofilm
community of microO working together
What makes an endospore so resistant?
not totally understood, but…
calcium (complexed with dipicolinic acid)
small, acid soluble, DNA binding proteins (SASPs)
dehydrated core
spore coat
DNA repair enzymes
Biofilm
community of microO working together
Sporulation
commences when growth ceases, lack of nutrients complex multistage process 1. cell division 2. plasma membrane pinches off cell into two areas 3. cell dies 4. cortex forms 5. spore finishes 6. vegetative cell falls away
Biofilm
community of microO working together
Transformation of spore to vegetative cell
- activation; prepares spore for germination
- germination; spore swelling, rupture/absorption of spore coat, loss of resistance, increased metabolic activity
- Outgrowth; emergence of vegetative cell
Biofilm
community of microO working together
Common Nutrient Requirements
Macroelements
Micronutrients
Macroelements
most cell dry weight:
C H O N S P
K+ Ca2+ Mg2+ Fe2+/3+
Required in relatively large amounts
Micronutrients
trace elements
Mn Zn Co Mo Ni Cu
enzyme cofactors
often supplied in water or media components
Biofilm
community of microO working together
Carbon, Hydrogen, Oxygen, electrons
need often satisfied together
carbon source often provides H, O and electrons
C/H/O: biosynthesis
electrons: energy + reduction during biosynthesis
Autotrophs
CO2 sole or principal biosynthetic carbon source
Heterotrophs
reduced, preformed, organic molecules from other organisms
Phototrophs
light as energy source
Chemotrophs
oxidation of organic or inorganic compounds as energy source
Lithotrophs
electrons from reduced inorganic molecules
Organotrophs
electrons from organic molecules
Biofilm
community of microO working together
Majority of microO studied…
photoautotrophs + chemoheterotrophs
Most pathogens…
chemoheterotrophs
Photoorganoheterotrophs
polluted lakes
Chemolithoautotrophs
oxidation of reduced inorganic compounds
Chemolithoheterotrophs
important in nutrient cycling in ecosystems
mixotroph
can use multiple metabolic strategies
Requirements for nitrogen, phosphorus, and sulfur
needed for synthesis of key molecules
nitrogen; organic molecules, ammonia, nitrogen gas
phosphorus; inorganic phosphate
sulfur; sulfate via assimilatory sulfate reduction
Growth Factors
essential cell components; cells can't synthesize must be supplied by environment AA's purines and pyrimidines vitamins - enzyme cofactors
Biofilm
community of microO working together
Growth-response assay
measure concentrations of growth factors in a preparation
comparison of known to std. curve
Industrial fermentation
production of vitamins by microO
vit B12, C
Uptake of nutrients
passive diffusion
facilitated diffusion
active transport
iron uptake
Biofilm
community of microO working together
Passive diffusion
High to low concentration
non-polar molecules
Water, O2 CO2
Facilitated diffusion
similar to passive, not E dependent, high to low conc. size of gradient impacts uptake rate Carrier molecules smaller conc. gradient required transport of glycerol, sugars, AA's more prominent in eukaryotic cells
Biofilm
community of microO working together
Biofilm
community of microO working together
Active Transport
Against conc. gradient E dependent - ATP or proton motive force Conc. molecules inside of cell Requires carrier proteins (Carrier Sat. effect) ABC transporters group translocation
ATP Binding Cassette (ABC) transporters
conserved in all three domains
pore: 2 TM domains, nucleotide binding domains (ATP)
substrate binding protein; in periplasm, deliver molecule to transporter
sugars
AAs
certain antibiotics
Group Translocation
molecules modified during transport, energy dependent
ex. sugar phosphotransferase system (PTS)
widely distributed in bacteria, many faculative anaerobes, not in most aerobes
Phosphoenolpyruvate: sugar phosphotransferase system (PTS)
transport of many carbohydrates
PEP phosphorylates enzyme 1 phosphorylates heat-stable protein (HPr) phosphorylates enzyme IIA, IIB, for transport
Biofilm
community of microO working together
Energy for active transport
ATP hydrolysis
H+ gradients from electron transport; direct energy, indirect energy
H+ gradients: direct energy
lactose permease (symporter), facilitative diffusion Na/H+ exchanger (antiporter)
H+ gradients: indirect energy
Na+ symporter, indirectly powered by proton motive force Na from Na/H+ exchanger
Biofilm
community of microO working together
Iron Uptake
ferric iron (Fe3+) insoluble; uptake difficult
siderophores
aid uptake of Fe3+ enterobactin secreted; complexes with Fe3+ complex transported In Gm- complex bound by receptor OM periplasm: either Fe3+ released or complex transported via ABC
Biofilm
community of microO working together
Getting things through the Gm- OM
small molecules - generalized porins
large molecules - specialized porins
Specific carriers - iron uptake
Culture media
preparations that support growth
can be liquid or solid
solidify with agar
Biofilm
community of microO working together
Defined (synthetic) media
components/concentrations known
controlled growth environment
can be used for certain bacteria that are known well
Complex media
contain some ingredients of unknown composition and/or concentration
Peptones - protein hydrolysates from partial digestion of various proteins
extracts - aqueous; beef or yeast
agar (solidify liquid medium) - sulfated polysaccharide
Selective media
favors growth of some microO; inhibits others
ex. MacConkey agar selects for Gm- bacteria
Differential media
distinguish between different groups of microO based on their biological characteristics
ex. blood agar - hemolytic vs nonhemolytic
ex. MacConkey agar - lactose fermenters vs nonfermenters
Blood agar
enriched and differential
hemolytic alpha and beta vs nonhemolytic
MacConkey agar
selective and differential
inhibit growth of Gm+, Gm- with acidic products red
Spread plate technique
best for less dense culture
Streak plate technique
best for very dense culture
Pour plate technique
sample diluted, serial dilutions
most control, can determine number of bacteria in original culture
Colony Morphology and Growth
growth most rapid at colony edge
biofilms on surfaces in nature
