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Common Traits of Bacteria Prokaryotes Formyl-methionine is the first amino acid in proteins Unique structures shared by most species
Peptidoglycan Features of gene expression machinery
RNA Polymerase Ribosome Good targets
for antibiotics
L-ornithine in Deinococcus
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Undiscovered Bacteria Many species uncharacterized
Many bacteria cannot yet be grown Unclassified organisms
Identified solely through rRNA sequence Projects to amplify all DNA in some habitats
Environmental samples Habitat is known rRNA is sequenced Can sometimes give provisional identification
Candidate species Some physiological characterization beyond DNA sequence
is known
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Major Well Studied Bacterial Phyla Deep-branching thermophiles
Diverged early from archaea and eukaryotes
Lateral gene transfer with archaea Cyanobacteria
Oxygenic photoautotrophs with thylakoid membranes
Gram-positive bacteria Multiple layers of peptidoglycan,
teichoic acids Low GC: Firmicutes High GC: Actinobacteria
Gram-negative bacteria with LPS Proteobacteria
Alpha Berta Gamma Delta Epsilon
Nitrospira
Bacteroidetes/Chlorobi group Gram-negative Obligate anaerobe and/or green
sulfur phototroph Spirochetes
Narrow coiled cell with sheath Chlamydia/ Planctomycetes/
Verrucomicrobia Lack peptidoglycan Subcellular structures analogous
to eukaryotes
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Deep-Branching Thermophiles Hyperthermophiles
Fastest growing cells known (10 min generation time) Most grow at > 70°C, some in near-boiling water (95°C)
Aquificales Oxidize hydrogen
Thermotogales Sheathed, obligate anaerobic heterotrophs
Thermales Original source for Taq polymerase for PCR
Deinococcus Lives at lower temperatures Stains gram-positive Peptidoglycan contains ornithine Extremely radiation-resistant
Survived Chernobyl Very rapid DNA repair
Deinococcus
Mass of pink filamentous Thermus spec.
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Cyanobacteria Profound importance for all ecosystems Oxygenic phototrophs
Chlorophyll a and b Accessory pigments (phycocyanin,
phycoerythrin)
Fix CO2
Many fix nitrogen Specialized cell types (heterocysts)
Subcellular structures Thylakoids
Site of photosynthesis Similar to chloroplasts
Carboxysomes-lipid bodies Gas vesicles for buoyancy
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Cyanobacteria Can secrete protective mucilage Single celled Filamentous
Multiple cells growing in a line
Colonial Large cell aggregate with anaerobic center
Many form akinetes Specialized spore cells
Survive long periods of dessication Germinate when conditions improve
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Gram-Positive Firmicutes Low GC content Rods and cocci No outer membrane
Thick cell wall Many are pathogens
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Bacillales Bacillus
Aerobic spore former
Listeria Staphylococcus
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Clostridiales Clostridium
Anaerobic endospore former Toxin producers
Tetanus Botulinum Gas gangrene
Epulopiscium “Live birth”
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Gram-Positive Endospores Extremely heat-resistant for millennia Toxin-formers
Clostridium Tetanus, botox, gangrene
Bacillus Anthrax, Bt
Spore forms inside mother cell
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Lactobacillales
LactobacillusUsed in dairy cultures
StreptococcusHuman normal flora“Strep throat”Flesh eating disease
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Mollicutes Lack cell wall
Flexible cell shape Pass through sterile filters
Require animal host Cholesterol
Mycoplasma M. pneumoniae
Used to attach to host cell
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Actinobacteria High GC Actinomycetales
Actinomycetes Streptomyces
Antibiotic producer Corynebacteriaceae
C. diphteriae Mycobacteriaceae
Acid fast M. tuberculosis M. leprae
Bifidobacteriales Colinize breast fed infants Used in dairy production
Propinibacteria P. acnes Cheese porduction
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Actinobacteria Many form long, multicellular filaments
Aerial mycelia carry arthrospores Wind blows spores to new sites
Streptomyces Very large genome Source of many antibiotics
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Gram-Negative Proteobacteria Largest group
Five major classes Many “light-supplemented” heterotrophs
Purple light receptorsUse of inorganic
electron donorsHighly adaptable
metabolism
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Alpha Proteobacteria Photoheterotrophs
Rhodospirillum Endosymbionts
Rhizobium, Agrobacterium in plants Root nodules, plant tumors
Rickettsias in animals Obligate intracellular parasites
Rocky Mountain spotted fever
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Beta Proteobacteria Lithotrophs
Nitrate, sulfur, iron oxidizers Nitrosomonas used in
wastewater treatment
PathogensBurkholderiaNeisseria gonorrhoeae
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Enteric Gamma Proteobacteria Facultative anaerobic fermenting rods
Many are motile Many form biofilms Normal flora
Escherichia coli Proteus
Pathogens Salmonella Shigella
Aerobic non-fermenting rods Some in biofilms, some pathogens
Pseudomonas
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Delta Proteobacteria Myxococcus xanthus
Attacks other bacteria in “packs” Social movement
Aggregates into fruiting bodiesDisperses myxospores
Bdellovibrio bacteriovorusParasitizes other bacteriaGrows in periplasmLyses host
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Epsilon Proteobacteria Smallest group of proteobacteria Helicobacter pylori
Cause of stomach ulcers Burrows below protective mucous layer
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Nitrospirae Spiral shape Most oxidize nitrite to nitrate
Nitrospira Leptospirillum
Oxidizes iron, fixes carbon
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Bacteroidetes Obligate anaerobes
Bacteroides Major flora of human colon Break down toxins in food Provide food
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Spirochetes Flexible, narrow spiral shape
Flagella at ends Fully enclosed within periplasm Form axial filament Flagellar rotation turns whole cell
Treponema pallidum
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Chlamydiae Obligate intracellular parasites Life cycle
Small elementary bodies Survives outside host cells Transferred to new host Similar in function to a spore
Larger reticulate body Grows within cells Does not survive outside host
C. trachomatis Leading cause of sexually transmitted
diseases among young population Morbidity Infertility
Elementary
Reticulate
36 – 48h
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Planctomycetes Multiple internal membranes
Double membrane surroundsnucleoid
Similar to eukaryotic nucleus?
Verrucomicrobia Irregular shape
Contains tubulin Horizontal gene transfer from
eukaryote?
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Endurance Forms of Bacteria
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Concept QuizMatch the bacterial group to the spore form that it creates
a. Cyanobacteria 1. Myxospores
b. Firmicutes 2. Arthrospores
c. Delta Proteobacteria 3. Endospores
d. Actinobacteria 4. Akinetes