Ch. 11: The Prokaryotes \: Domains Bacteria and Archaea

Atypical Bacteria

• Not Typical

1. Fungus-like Bacteria

2. Acid-Fast Bacteria

3. Mycoplasmas

4. Chlamydias

5. Rickettsias

Fungus-Like (Filamentous) Bacteria

• Gram-positive Bacilli

• Branching Filaments

• Fungus-Style reproductive spores

• Prokaryotes

Streptomyces spp.

• Fungus-Like (Filamentous) Bacteria

  • Most important source of antibiotics

  • Myco- : fungus or something like it (filamentous)

  • One of the most commonly isolated from soil

  • Strict Aerobes

  • Near 500 species describes within this genus

• Why does Streptomyces spp. have so many toxic substances to bacteria?

• What does it produce?

• This is due to competition in the soil. In this case, it will compete for oxygen in the body.

• Produced a gaseous compound called geosmin which gives soil the musty, fresh smell.

What kind of spores does streptomyces spp. create

Asexual spores called conidiospores and are capable of germinating into new colonies

Actinomyces 

• Fungus-Like (Filamentous) Bacteria

  • Facultative(not required or necessary) anaerobes 

  • Greek Actino=ray

Where are actinomyces spp. found

Found in mouth and throat of humans and animals (part of normal flora)

What filaments and spores does actinomyces spp. have?

• Branching filaments and spore-case(sack)(sporangium)

• Reproductive spores called sporangiospores

What causes Atinomycosis?

• Actinomyces israelii causes Atinomycosis

What does Actinomycosis do to the body?

• Called lumpy jaw

• tissue-destroying disease

• affects head, neck, and lung

  • Large abscess

  • Sulfur granules in pus

  • Opportunistic disease

What doesn’t classify as fungi?

• Non-membrane bound organelles e.g. mitochondria and nucleus

• Reproducing by binary fission

• Susceptible to penicillin not to anti-fungal agents

Acid Fast Bacteria

• Gram positive bacilli 

• Wax coat on cell wall similar to Gram (-)

What is the difference between the outermost layer of the Acid Fast Bacteria and Gram(-) 

Outermost layer uses mycolic acids instead of Lipopolysaccharides

Nocardia spp.

• Weakly acid fast

• Requires special acid fast stain 

• Aerobic 

• Prokaryotic, but grows like a fungus 

• Very common in soil

• Norcardia asteroids and other 

Nocardia asteroides-nocardiosis

• Follows penetration from the soil via a wound 

• Nocardiosis growing back through ribs from lungs to skin 

• When inhaled, the diseases strikes the lungs, where multiple abscesses form 

• Symptoms can be similar to tuberculosis 

• Reports of death from nocardiosis have been linked to HIV infection 

• 60% of cases associated with existing immune compromise  

Mycobacterium spp.

• Common Species 

  • M. tuberculosis (Tuberculosis)

  • M. leprae (Leprosy)

  • M. Ulcerans (Buruli ulcer)

Mycobacterium spp.

• Aerobic, non-endospore forming rod

• Myco, meaning fungus-like die to their filamentous growth 

  • Sometimes they form clumps 

Cuasing slow growth rate of Mycocbacterium; sometimes take weeks to form visible colones

Mycobacterium Tuberculosis

• 20 hr or more generation time (1 bacteria cell undergo binary fission to become 2)

• Very resistant die to wax coat; survive in dry sputum for weeks 

  • Sputum is thick slimy mucus that is produced in the lungs and coughed up

Mycobacterium Leprae

• Optimum growth temp. of 30 degrees celsius 

• Obligate intra-cellular parasite that lacks many genes for independent survival 

• Can’t grow on artificial media

  • T-soy, ect.

• Grows on armadillos/nude mice footpads used to culture the bacteria

• Extremely long incubation period of of 20 years.

Mycobacterium Ulcerans

• Ulcerative condition on the skin and subcutaneous fat cells by a toxic mycolactone; prevalence increasing in the world; pathogen enters through a minor cut or insect bite

Acid Fast Stains

Primary stain: Carbolfuchsin

Mordant: heat 

Decolorization: Acid alcohol 

• 1% HCL in 95% alcohol

• Acid fast bacteria hold the primary stain because the carbolfuchsin is more soluble in the mycolic acid that acid alcohol 

• non-acid-fast bacteria decolorize 

…

Mycoplasmas

• Smallest known bacteria… is only 5% of that odf a typical bacillus; originally considered as a virus 

• Small size allows them to pass through filters 

• Are the only prokaryotes… surrounded only by a cytoplasmic membrane, therefore are highly pleomorphic 

  • Pleomorphic: occurring in many distinct shapes or forms 

• Sterols (only found in eukaryotic cell membrane)

  • Cholesterol

• No fixed shape 

• Produce filaments that resemble fungi growing on artificial media with sterols; forming “fried egg” colonies

M. Pneumoniae

Most significant human pathogen of this genus

• ………

Chlamydias 

• Cell wall but no peptidoglycan

• Stains gram (-)

• Oval coccoid (similar to coccus)

• Obligate intracellular

  • will only grow inside a living cell

• Infective agents: