The Prokaryotes: Bacteria February 4, 2015. The Prokaryotes.

The Prokaryotes:

BacteriaFebruary 4, 2015

The Prokaryotes

Domain Bacteria

Proteobacteria

Gram-negative

Chemoheterotrophic

Divided into 5 groups

Alphaproteobacteria

Betaproteobacteria

Gammaproteobacteria

Deltaproteobacteria

Epsilonproteobacteria

The Alphaproteobacteria

Capable of growth in nutrient-deprived environments

Some contain prosthecae. Stalk like buds function to anchor the bacteria and absorb nutrients

Pelagibacter ubique

20% of prokaryotes in oceans

Constitutes 0.5% of all prokaryotes

1354 genes (relatively small genome)

Symbiotic bacteria that have lower metabolic requirements have the smallest genomes

Insert Fig 11.2b

Figure 11.2b Caulobacter.

May grow in laboratory water baths


Human pathogens (zoonosis) Bartonella:

B. henselae: cat-scratch disease. Infects RBCs.

Brucella:

B. melitensis: brucellosis. Survives in phagocytes

Obligate intracellular parasites Rickettsia: arthropod-borne, spotted fevers

R. prowazekii: epidemic typhus. Transmitted by lice.

R. typhi: endemic murine (mice) typhus

R. rickettsii: Rocky Mountain spotted fever. Damage blood capillaries

Ehrlichia: live obligately in white blood cells

Tickborne (Lone star tick)

Causes ehrlichiosis which can be fatal

Figure 11.1 Rickettsias.

Slime layerScattered rickettsias

Chicken embryo cell

Nucleus

Masses of rickettsias in nucleus

A rickettsial cell that has just been released from a host cell

Rickettsias grow only within a host cell, such as the chicken embryo cell shown here. Note the scattered rickettsias within the cell and the compact masses of rickettsias in the cell nucleus.


Wolbachia: live in insects and other animals

Only live inside of cells of their hosts (insects)

Difficult to culture

75% of all species of animals carry this bacteria

May lyse the cells of the infected host or cause the infected host to not reproduce

Applications of Microbiology 11.1b In an infected pair, only female hosts can reproduce.

Neither infectedUninfected offspring

Male infectedNo offspring

Female infectedInfected offspring

Both infected Infected offspring

Unfertilized female infectedInfected female offspring

Wolbachia

Females

Males


Plant pathogen

Agrobacterium: insert a plasmid into plant cells, inducing a tumor (crown gall)

Figure 9.19 Crown gall disease on a rose plant.

Crown gall


There are some industrial important alphaproteobacteria

Acetobacter

Gluconobacter

Both produce acetic acid (vinegar) from ethanol

The Betaproteobacteria

Often uses nutrient substances that diffuse away from areas of anaerobic decomposition of organic matter

Hydrogen gas

Ammonia

Methane

The Betaproteobacteria

Burkholderia

Motile (single flagella), aerobic, gram-negative rod

Capable of degrading 100 different organic molecules

Confers the ability to contaminate drugs in hospitals

Nosocomial infections (cystic fibrosis)

Bordetella

Chemoheterotrophic; rods

B. pertussis

Non-motile, aerobic gram-negative rods

Causative agent of pertussis (whooping cough)

Neisseria

Aerobic gram-negative cocci

Inhabits mucous membranes of mammals

Causative agents of gonorrhea and meningococcal meningitis

Figure 24.7 Ciliated cells of the respiratory system infected with Bordetella pertussis.

B. pertussis

Cilia

The Gammaproteobacteria

Constitute the largest subgroup of Proteobacteria

Order Pseudomonadales Gram-negative rods or cocci

Genus Pseudomonas (rods)

Common in soil

Opportunistic pathogens (urinary tract, burns, wounds….may cause sepsis and meningitis)

Capable of growth in antiseptics. High resistance to antibiotics (encodes for efflux pumps)

Excrete water soluble pigments into media (blue-green pigmentation with UV light)


Pseudomonadales

Genus Moraxella

Aerobic coccobacilli (between coccus and rod)

Conjunctivitis : inflammation of the conjunctiva


Legionellales

Legionella

Found in streams, warm-water pipes, cooling towers

Can survive and reproduce within aquatic amoebas

Difficult to eradicate in water systems

L. pneumophilia causes legionellosis (pneumonia)

Coxiella

Obligate intracellular pathogen

Causative agent of Q fever

Transmitted via aerosols or unpasteurized milk


Vibrionales

Facultative anaerobic gram-negative rods

Found in coastal water

Vibrio cholerae causes cholera

Profuse and watery diarrhea (dehydration)

V. parahaemolyticus causes gastroenteritis (inflammation of intestines)

May be transmitted to humans via undercooked shellfish

Vibrio vulnificus causes cellulitis or septicemia

Figure 11.8 Vibrio cholerae.

The Gammaproteobacteria Enterobacteriales (enterics)

Peritrichous flagella; facultatively anaerobic

Active fermenters of glucose and other carbs

Fimbriae helps bacteria attach to membranes

Sex pili aid in DNA transfer

Enterobacter Erwinia Escherichia Klebsiella Proteus Salmonella Serratia Shigella Yersinia


Order Pasteurellales

Haemophilus

Inhabit mucous membranes of upper respiratory tract, mouth, vagina, and GI tract

Requires X (heme) and V (NAD+, NADP+) factors

Laboratory tests for X and V factors help identify organism

Causes meningitis/earaches in children. Epiglotitis, bronchitis, and pneumonia

The Deltaproteobacteria

Includes bacteria that are predators of other bacteria

Bdellovibrio

Attacks other gram-negative bacteria

Reproduces in the periplasm of the infecting host

How can Deltaproteobacteria be beneficial?

The Epsilonproteobacteria

Gram-negative helical or curved rods

Campylobacter

Microaerophile

One polar flagellum

Leading cause of food-borne gastroenteritis

Helicobacter

Multiple flagella

Most common cause of peptic ulcers in humans

Infection has been associated with the development of stomach cancer

50% of all humans are colonized with H. pylori

The Prokaryotes: Bacteria February 4, 2015. The Prokaryotes.

Documents

Transcript of The Prokaryotes: Bacteria February 4, 2015. The Prokaryotes.