Lecture: 4-6 Diversity of Bacteria Flashcards
What are firmicutes?
- a type of bacteria
- classically gram positive bacteria
- mostly organotrophs
- range from obligate aerobes to obligate anaerobes
examples: lactic acid bacteria and endospore formers
What are lactic acid bacteria?
- an example of firmicutes
- they are aeroteolerant anaerobes
- convert simple sugars into lactic acid
- no use of electron transport chain, no external electron acceptor
location: found in carbohydrate rich areas : plant decay, mouth/gastrointestinal tract (vagina), and the dairy / pickling industry (adds flavour, acids inhibit other microbes)
What do lactic acid bacteria (firmicutes) breathe?
- they are aerotolerant anaerobes, so they do not breathe oxygen but they are ok with it in their environment
What are endospore formers? provide an example
- eg; bacillus
- mostly found in soil/sediment, endospores are a dormancy stage (resistant to heat, UV, desiccation, etc) - some stay viable for decades
What are endospores specifically? What do they surround?
- endospores have a thick cortex of modified peptidoglycan
- cortex surrounds the core, which holds the nucleoid and inactive cytoplasm (low water content)
- the DNA are bound to protective, small, acid soluble proteins!
What is the process of sporulation?
- sporulation is when the spore is actually released
What is responsible for the pathogenicity of pathogenic endospore formers?
- partly due to extremely potent toxins
Describe actinobacteria
- another form of bacteria
- gram positive cell architecture
- organotrophs: mostly aerobic
- abundant in soil
- mostly filamentous
- some are unicellular
Describe filamentous bacteria
- filaments indefinite length (branch and extend as mycelium, many copies of genomes)
- release thick walled spores called arthrospores or exospores
- resist desiccation, different from the endospores of firmicutes (eg; produced by multiple fission), have reproduction and function in dispersal
How do filamentous actinobacteria gain their nutrients?
- acquire nutrients by growing substrate mycelium
- then aerial mycelium grow and release arthrospores
Do actinobacteria have multiple copies of genes? Why?
- filamentous Bacteria have dozens of copies of chromosomes which can then be released as spores from the arthrospores (helps in reproduction and dispersal)
Describe streptomyces?
- a form of actinobacteria
- grow on (break down) durable polysaccharides (ligin, chitin)
- important in soil decomposition
- also source of antibiotics
~50% of therapeutic antibiotics come from streptomyces
Describe mycobacterium?
- a type of actinobacteria
- mostly found in soil but some pathogens (eg; tuberculosis)
- slow growth, highly resistant to antibiotics, does not stain gram positive
Describe proteobacteria
- another form of bacteria
- gram negative
- range from largest prokaryote to smallest parasite
- metabolically diverse: organotrophs, lithographs, phototrophs,
- major phylogenetic groups: alpha, gamma, beta - proteobacteria
Describe enteric bacteria
- an organotrophic (gamma) proteobacteria
- 40 different genera
- facultative anaerobes: can respire via nitrate reduction, and ferment simple sugars
- animal hosts (especially intestinal tract)
- many are (or can be) pathogenic
What is a MacConey Medium?
an example of a medium that differentiates bacteria based on their fermentation ability
eg; can distinguish between lactose fermenting bacteria (acidic turns pink) and non lactose fermenting
Describe E.Coli
- an example of proteo bacteria
- likely the best studied bacteria (fundamental cell biology and biochemistry), and a mainstay for molecular cloning
- mainly reside in animals intestines
- indictor organism for fecal contamination of water
Describe Pseudomonads
- an example of proteobacteria
- a facultative anaerobe
- limited fermentation abilities, uses many alternatives as electron acceptors including denitrification
- pseudomonas aeruginosa
- found on soil but also pathogenic
- burn wounds, lungs (esp. CF)
