Lecture: 4-6 Diversity of Bacteria Flashcards
1
Q
What are firmicutes?
A
- a type of bacteria
- classically gram positive bacteria
- mostly organotrophs
- range from obligate aerobes to obligate anaerobes
examples: lactic acid bacteria and endospore formers
2
Q
What are lactic acid bacteria?
A
- 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)
3
Q
What do lactic acid bacteria (firmicutes) breathe?
A
- they are aerotolerant anaerobes, so they do not breathe oxygen but they are ok with it in their environment
4
Q
What are endospore formers? provide an example
A
- eg; bacillus
- mostly found in soil/sediment, endospores are a dormancy stage (resistant to heat, UV, desiccation, etc) - some stay viable for decades
5
Q
What are endospores specifically? What do they surround?
A
- 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!
6
Q
What is the process of sporulation?
A
- sporulation is when the spore is actually released
7
Q
What is responsible for the pathogenicity of pathogenic endospore formers?
A
- partly due to extremely potent toxins
8
Q
Describe actinobacteria
A
- another form of bacteria
- gram positive cell architecture
- organotrophs: mostly aerobic
- abundant in soil
- mostly filamentous
- some are unicellular
9
Q
Describe filamentous bacteria
A
- 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
10
Q
How do filamentous actinobacteria gain their nutrients?
A
- acquire nutrients by growing substrate mycelium
- then aerial mycelium grow and release arthrospores
11
Q
Do actinobacteria have multiple copies of genes? Why?
A
- filamentous Bacteria have dozens of copies of chromosomes which can then be released as spores from the arthrospores (helps in reproduction and dispersal)
12
Q
Describe streptomyces?
A
- 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
13
Q
Describe mycobacterium?
A
- a type of actinobacteria
- mostly found in soil but some pathogens (eg; tuberculosis)
- slow growth, highly resistant to antibiotics, does not stain gram positive
14
Q
Describe proteobacteria
A
- 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
15
Q
Describe enteric bacteria
A
- 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
