Chapter 18 Lecture Outline Bacterial Diversity. Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 2 Common Traits of Bacteria Prokaryotes

Chapter 18Lecture Outline

Bacterial Diversity

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 2

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


Bacterial Tree


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


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


Bacterial Tree


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.


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


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


Cyanobacteria


Gram-Positive Firmicutes Low GC content Rods and cocci No outer membrane

Thick cell wall Many are pathogens


Bacillales Bacillus

Aerobic spore former

Listeria Staphylococcus


Clostridiales Clostridium

Anaerobic endospore former Toxin producers

Tetanus Botulinum Gas gangrene

Epulopiscium “Live birth”


Gram-Positive Endospores Extremely heat-resistant for millennia Toxin-formers

Clostridium Tetanus, botox, gangrene

Bacillus Anthrax, Bt

Spore forms inside mother cell


Lactobacillales

LactobacillusUsed in dairy cultures

StreptococcusHuman normal flora“Strep throat”Flesh eating disease


Mollicutes Lack cell wall

Flexible cell shape Pass through sterile filters

Require animal host Cholesterol

Mycoplasma M. pneumoniae

Used to attach to host cell


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


Actinobacteria Many form long, multicellular filaments

Aerial mycelia carry arthrospores Wind blows spores to new sites

Streptomyces Very large genome Source of many antibiotics


Gram-Negative Proteobacteria Largest group

Five major classes Many “light-supplemented” heterotrophs

Purple light receptorsUse of inorganic

electron donorsHighly adaptable

metabolism



Alpha Proteobacteria Photoheterotrophs

Rhodospirillum Endosymbionts

Rhizobium, Agrobacterium in plants Root nodules, plant tumors

Rickettsias in animals Obligate intracellular parasites

Rocky Mountain spotted fever


Beta Proteobacteria Lithotrophs

Nitrate, sulfur, iron oxidizers Nitrosomonas used in

wastewater treatment

PathogensBurkholderiaNeisseria gonorrhoeae


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


Delta Proteobacteria Myxococcus xanthus

Attacks other bacteria in “packs” Social movement

Aggregates into fruiting bodiesDisperses myxospores

Bdellovibrio bacteriovorusParasitizes other bacteriaGrows in periplasmLyses host


Epsilon Proteobacteria Smallest group of proteobacteria Helicobacter pylori

Cause of stomach ulcers Burrows below protective mucous layer


Nitrospirae Spiral shape Most oxidize nitrite to nitrate

Nitrospira Leptospirillum

Oxidizes iron, fixes carbon


Bacteroidetes Obligate anaerobes

Bacteroides Major flora of human colon Break down toxins in food Provide food


Spirochetes Flexible, narrow spiral shape

Flagella at ends Fully enclosed within periplasm Form axial filament Flagellar rotation turns whole cell

Treponema pallidum


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


Planctomycetes Multiple internal membranes

Double membrane surroundsnucleoid

Similar to eukaryotic nucleus?

Verrucomicrobia Irregular shape

Contains tubulin Horizontal gene transfer from

eukaryote?


Endurance Forms of Bacteria


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


Concept QuizAll of the following major groups contain phototrophic bacteria except

a. Chlorobi

b. Cyanobacteria

c. Proteobacteria

d. Spirochetes

Documents

Chapter 18 Lecture Outline Bacterial Diversity. Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 2 Common Traits of Bacteria Prokaryotes