3. Phylum Proteobacteria

L. 6: Bacteria Domain (II). 2nd Biology ARA 2013-2014

3. Phylum Proteobacteria

GRAM NEGATIVE BACTERIAWide morphological and metabolic diversity.

Clinical, environmental, and industrial relevancePhylum with highest number of cultured representatives

5 groups (based on 16S rRNA): a, b, g, d, and e


2. Phylum Proteobacteria


3. Phylum Proteobacteria3.1. a-Proteobacteria: Rhizobium

N2 fixing organisms:

Some cyanobacteria (Bacteria)Some anoxygenic phototrophs (Bacteria)Some chemolithotrophs (Bacteria/Archaea)Some chemoorganotrophs (Bacteria/Archaea)

Some chemoorganotrophs (Bacteria)

FREE LIVING

SYMBIONTS

E.g. symbionts of leguminous

plants



RECOGNITION

NOD FACTORS


3. Phylum Proteobacteria3.1. a-Proteobacteria. Agrobacterium

pTi


3. Phylum Proteobacteria3.1. a-Proteobacteria: “acetic acid bacteria”

They oxidize sugars and alcoholsAcidophilic

Acetobacter

Gluconobacter

H20 O2

ETHANOL

ETHANAL

ACETIC ACID

e- e-


3. Phylum Proteobacteria3.1. a-Proteobacteria: Caulobacter

Prosthecae: cytoplasmic extrusions (stalks, hyphae, or appendages)Budding division (mother cells retain their original identity)Attachment, increased surface-to-volume ratio, reduced cell sinking Aquatic bacteria (either planctonic or benthonic)

PROSTHECAE


3. Phylum Proteobacteria3.2. b-Proteobacteria. Neisseria

Aerobic diplococcusPenicillin sensitivePathogens and normal microbiotaCarrier state

N. meningitidis (“meningococcus”)

Aerosols

Nasopharynx

Blood stream:Meningitis

(sudden onset of headheache, vomiting and stiff neck)

Intravascular coagulation shock


3. Phylum Proteobacteria3.2. b-Proteobacteria: Neisseria

N. gonorrhoeae (“gonococcus”)

- Very sensitive to environmentalstress (drying, sunlight, UV light…)- High incidence (STD, ETS) - Mild symptoms* in women(asymptomatic carriers). PID- Complications if untreated

Sexual contact

Mucous membranes of the genitourinary tract

Reasons?


3. Phylum Proteobacteria3.2. b-Proteobacteria. Acidithiobacillus

Thiobacillus ferrooxidans

Chemolithotroph: donor: Fe2+ / acceptor: O2

They use large amounts of substrate (they fix CO2)

pH acidic (acidiphilic)

Acid mine drainage (formation of H2SO4 and Fe3+) (O2, water and bacteria)

Biolixiviation


3. Phylum Proteobacteria3.2. b-Proteobacterias. Zooglea

WASTEWATER TREATMENT

BOD:Biological Oxygen Demand


3. Phylum Proteobacteria3.3. g-Proteobacteria: Legionella

RodsComplex nutritional requirements (Fe)Resistent to b-lactamicTerrestrial and aquatic habitatsWaterborne, aerosols (no person-to-person)

Cases per 100.000 inhabitants. Spain

Emerging disease (1976)

L. pneumophilaLEGIONELLOSIS

Pontiac feverPneumonia


3. Phylum Proteobacteria3.3. g-Proteobacteria: Legionella

Legionella inside an alveolar macrophage


3. Phylum Proteobacteria3.3. g-Proteobacteria: Haemophilus

Haemophilus influenzae


3. Phylum Proteobacteria3.3. g-Proteobacteria: Pseudomonas

More than 100 speciesSome species utilize over 100 different compoundsAerobic chemoorganotrophic rods• Some chemolitotroph (H2, CO)

• Some anaerobic (NO3- / fermentation)

Sugar oxidation: Entner-Doudoroff pathwayFluorescent pigments


3. Phylum Proteobacteria3.3. g-Proteobacteria: Pseudomonas

Opportunistic pathogen; intrahospitalary infections Resistence plasmids (plasmids R)

Respiratory tract infectionsSkin infectionsBacteremiaEndocarditisJoint infectionsFastrointestinalinfectionsUTIEye infectionsCNS infectionsUpper respiratory tract infections

Cystic fibrosis complications

Pseudomonas aeruginosa


3. Phylum Proteobacteria3.3. g-Proteobacteria: Pseudomonas DEGRADATIVE

MEGAPLASMIDS


3. Phylum Proteobacteria3.3. g-Proteobacteria: Family Enterobacteriaceae

Enteric bacteria

Facultatively aerobic, gram negative rods• Fermentation of sugars to organic acids

• Some respire NO3- to NO2

- (never to N2)

Virulence factors and pathogenicity



Escherichia

Warm blooded animalsGut microbiota (comensals)Pathogenic strains: E. coli enterotoxigenic (ECET) E. coli enteropathogenic (ECEP) E. coli enterohemorrhagic (ECEH) (STEC)

E. coli O157:H7 E. coli O104:H14

GastroenteritisHemolytic uremic syndrom (HUS)

Urinary tract infections (UTI)


vitamin K


3. Phylum Proteobacteria3.3. g-Proteobacterias. Familia Enterobacteriaceae

Salmonella

Habitat: gastrointestinal tract of wild and domestic animals, birds, pets, and insects. Zoonosis.Main pathogenic serovars: S. typhimurium: salmonellosis (enterocolitis) S. typhi: typhoid fever



Shigella

Reservoir: infected gutS. dysenteriae: - Shigellosis or bacillary dysentery (“disentería bacilar”) - HUS

Shigella cells invading intestinal epithelium



Buboes (“bubones”)

Gangrene and black spots (“black death”)

Bacteria in lung tissue

Yersinia: Y. pestis PLAGUE (bubonic, pneumonic and speticemic). Zoonotic disease.


3. Phylum Proteobacteria3.3. g-Proteobacterias: Vibrio

Curved and straight rodsAquatic mediaMany species, some pathogenic: V. cholerae: cholera

CHOLERA TOXIN


3. Phylum Proteobacteria3.3. g-Proteobacteria: Photobacterium

FMNH2 + O2 + RCHO FMN + RCOOH + H2O + luzNADH

NAD+

FMN

luciferase

Autoinduction: “quorum sensing”

Inducer molecule: acyl homoserine lactone (AHL)


3. Phylum Proteobacteria3.4. d-Proteobacteria: Bdellovibrio

“Predator” of other bacteria


3. Phylum Proteobacteria3.4. d-Proteobacteria: SULFATE (AND SULFUR) REDUCING BACTERIA (SRB)*

Desulfo- (generally) or Desulfuro-They reduce sulfate/sulfur(acceptors)Final products: H2S

Strict anaerobes (anoxic environments)Group I:

Acetate cannot be used as donor

Sulfate reducing bacteria

Group II:

H2 and acetate can be used as donors

Sulfate reducing bacteria

Fixation of CO2 (acetil-CoA pathway)

Group III:

H2 or organic matter as donors

S and sulfite reducing bacteria (NEVER sulfate)

DonorsH2 O. M.

*Some sulfate-reducing bacteria are not delta-proteobacteria


3. Phylum Proteobacteria3.4. d-Proteobacteria: SULFUR AND SULFATE REDUCING BACTERIA

m.o.

NO3-

Mn+4

Fe+3

SO4-2

CO2

E’ (V

)

+0.8

-0.2

0

Stratification of electronic acceptorsLimited organic matterMost important metabolism: sulfate reductionCompetence (or not---) with methanogenic Archaea

Marine sediments

Consortia of SRB/methane oxidizing Archaea

O2


3. Phylum Proteobacteria3.4. d-Proteobacteria: MYXOBACTERIA

Vegetative cells: long rods without flagella (names: Myxo…). Gliding.Fruiting bodies: cell-to-cell communication and differentiation


3. Phylum Proteobacteria3.5. e-Proteobacteria: Campylobacter and Helicobacter (both microaerophilic)

Campylobacter: acute gastroenteritis, food borne disease (chicken meat…)


Helicobacter: gastritis and ulcers

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2005/marshall-lecture.pdf


3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: NITRIFYING BACTERIA

a, b, g , and d ProteobacteriaElectron donors: NH4

+ and NO2- / Acceptor: O2 (Nitroso…/ Nitro…)

They consume large amounts of substrate: chemolithoautotrops/ chemolithoheterotrophs Soils and waters; ammonia-rich sites; leaching of NO3

-

NH4+ NO2

- NO3-

Nitrosomonas Nitrobacter

AMO: ammonia monooxygenase

NOR: nitrite oxidoreductase

Nitrification

Nitrospira (independent phylum)Nitrifying Archaea


3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: SULFUR OXIDIZING BACTERIA

a, b, g, e Proteobacteria

Donors: H2S, S0, S2O32-, metallic suflides, H2 / Acceptor: O2 (sometimes NO3

- )

S0 accumulation inside or outside the cell

Acidithiobacillus: acidiphilic (A. ferrooxidans FeS2, Fe2+); autotrophs

Thiomargarita: anaerobic oxidation (acceptor: NO3-)

L. 6: Bacteria Domain (II). 2nd Biology ARA 2013-2014Hydrothermal vents: H2S, H2, CO2, O2, N2...


3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: PURPLE BACTERIA

Anoxygenic phototrophs

Reaction centre: bacteriochlorophyllsAntenna pigments: BChl + carotenoids

Photosynthetic systems: invaginations of the cytoplasmatic membrane


e-

BChl EXCITED

BChl

BASAL

Eo (-)

Eo (+)

LIGHT NO external electron donors for ATP

ATP: Cyclic photophosphorilation

H+H+

cte-

e-

BChl EXCITED

BChl BASAL

External electron donors for NAD(P)H

NAD(P)H: Reverse electronic flow

H+H+

cte-

H2SS0

Fe2+

S0

SO42-

Fe3+

NAD(P)+

NAD(P)He-


Images property of Fernando Santos


g-Proteobacteria (“purple sulfur bacteria”): highly sensitive to O2; highly tolerant to [H2S]

S compounds as electron donors. Photoautotrophs (Calvin cycle) Photoheterotrophs

N2 fixers

a/b-Proteobacteria (“purple nonsulfur bacteria”): more tolerance to O2; very sensitive to high [H2S]

Chenoorganotrophs, Photoheterotrophs, photoautotrophs

N2 fixers

Anoxic areas blooms

Sulfide-rich waters(SRB)


Meromictic lakes, microbial mats


Metabolic diversity of nonsulfur purple bacteria


Microbial mats: stratification of microbial populations driven by environmental gradients

Images property of Fernando Santos


3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: METHANOTROPHS

Methylotrophs vs. methanotrophs

Biotic and abiotic methane

Methanotrophs vs. methanogens

Where does the methane come from?


Type I Type II

3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: METHANOTROPHS (Methylo…)


Methane as energy source

Methane monooxygenase

Methano Methanol Formalhehyde CO2


Ribulose monophosphate pathway

Serine pathway

Type IIType I

Methane as carbon source

Methane Methanol Formalhehyde biomass


3. Phylum Proteobacteria3.6. OTHER PROTEOBACTERIA: RICKETTSIAS

a/g ProteobacteriaObligate intracellular parasites*Induce phagocytosis, do not survive outside hostsHighly specific energy metabolism*, synthesize few compoundsTransmitted by arthropod vectorsDamage to blood vessels

Epidemic tifus (Rickettsia prowazekii) Vector: human louse

Rocky Mountains spotty fever (Rickettsia rickettsii) Vector: tick

*Q Fever (Coxiella) Vectors: tick, aerosols, dairy productsOne bacteria is enough!! (Biological weapon)

Fever, headheach, weaknessRash

Organ infectionsHigh mortality untreated

*Exception

3. Phylum Proteobacteria

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