Module 7B Flashcards
Bacterial MVPs
what are some features of Firmicutes
- Gram-positive
- low GC content (~45-60%)
what are some features of Actinobacteria
- Gram-positive
- high GC content (>60%)
what are some notable genuses of Firmicutes
- Staphylococcus
- Lactic Acid Bacteria (Streptococcus & Lactococcus)
what do Staphylococcus & Micrococcus share in common
- possess aerobic metabolisms
- catalase positive
- resistant to desiccation and tolerate very high salt concentrations
- very common skin-associated bacteria
what are some features of lactic acid bacteria
- non-spore forming
- come in rods and cocci
- aerotolerant
- fastidious - have very complex nutritional requrements (can’t make some of the materials they need within the cell)
what is the difference between homofermenters and heterofermenters
homo - simply make lactic acid
hetero - make things in addition like ethanol and carbon dioxide
what does Streptococcus pyogenes cause
necrotizing fasciitis
what does Streptococcus pneumoniae cause
pneumonia and strep throat
what does Bacillus anthracis cause
anthrax
what is Bacillus thuringiensis active against
- insect larvae
- toxic for insect digestive tracts
- their digestive tracts cleave crystalline protoxin and it acts like broken glass
what is Bt toxin
the proteolytically cleaved protein in insect digestive tracts (Bacillus thuringiensis)
what is the structure of the spore bodies of Bacillus thuringienses
- there is an endospore surrounded by a parasporal body
- crystalline prototoxin (“cry protein”) is produced within the parasporal body
what are some features of Clostridium
- strict anaerobes
- produce spores
- Gram-positive
- completely rely on fermentation - a variety of substrates
what causes botulism
- Clostridium botulinum
- both toxin and spores are dangerous to inhale or ingest
- can be useful at low concentrations, causing localized flaccid paralysis (Botox)
which bacterium causes tuberculosis and leprosy
Mycobacterium tuberculosis, Mycobacterium leprae
what are some features of Mycobacterium
- difficult to stain, need to force stain in with heat
- have mycolic acids in their cell wall - extremely hydrophobic lipids
- very resistant to the penetration of chemicals
- colonies have a wax-like appearance
what are some features of actinobacteria
- highly filamentous
- grow as branching mycelia
- produce desiccation-resistant spores called conidia
- produce and secrete terpene compounds known as geosmins when they produce spores
- prolific producers of antibiotics
what are some features of cyanobacteria
- Gram-negative
- most are oxygenic phototrophs
- come in all kinds of shapes and sizes
- found everywhere
- most are photosynthetic and have chlorophyll A to capture light energy
- some produce cyanotoxins
- form heterocysts
what pigments are in cyanobacteria
phycocyanins (blue) & phycoerythrins (red)
what are heterocysts
- differentiated forms of cyanobacterial cells that some filamentous cyanobacterial species can produce
- lack the oxygen-evolving photosystem II
what is the purpose of heterocysts
to conduct nitrogen fixation
why do heterocysts have thick cell walls
to exclude oxygen, protecting the nitrogenase
what is the exchange between heterocysts and vegetative cells
- heterocysts fix nitrogen into ammonia which is then assimilated into amino acids and distributed to vegetative cells
- vegetative cells
