Lab IIIA: Introduction to Culturing and Characterizing Bacteria Flashcards
Are Bacteria are prokaryotic or eukaryotic microorganisms?
PROKARYOTIC
Through which process do bacteria divide?
Binary fission
In optimal growing conditions, one bacterium can divide into 2 daughter cells in roughly how many minutes?
in 20 minutes!! (A LOT)
(4 x 10^21 replicas of itself in 24H)
Culturing bacteria is necessary for WHAT?
for research applications and identification of bacteria.
Bacteria can be cultured in WHAT? (name 2 mediums)
- liquid medium
- semi-solid medium
What do we call a liquid medium?
a broth
What is a semi-solid medium made of?
made of agar (red algae protists; polysaccharides)
Name an advantage of liquid medium:
cells can reach very high cell concentrations
On agar, each cell can produce what?
an isolated, macroscopic colony by cell division over night
Bacteria can be cultured under different conditions such as WHAT? (3)
temperature, pH, and oxygen levels
The metabolic diversity in bacteria explains why they occupy almost every imaginable environment and ecological role on the planet. HOW SO? Tell me more about their metabolism (2):
some are photosynthetic = primary producers
MOST are not photosynthetic = decomposers or mutualists
What do we can species that infect plants and animals and cause diseases?
pathogenic bacteria (a minority of species)
What are great ways to identify and differentiate bacteria (2)?
using certain stains (gram +/-) or antibiotics
Why do we want to identify bacteria?
goes beyond the essential need of biological classification (taxonomy). It is essential to effectively treat infections. (important for clinical microbiologists)
Bacteria can be characterized at what 3 levels?
- colony level
- cell level
- molecular level
a colony from a particular bacterial species will have (3 things)?
- characteristic shape
- surface texture
- color
What is the cell wall of bacteria made of?
structural polymer -> peptidoglycan
What are the characteristics of a Gram-negative cell
- pink/red
- OUTER MEMBRANE
- THIN peptidoglycan
- plasma membrane
What are the characteristics of a Gram-positive cell
- purple/blue
- THICK peptidoglycan
- plasma membrane
(NO outer membrane)
Name 3 basic cell shapes
- Coccus
- Bacillus
- Spirillum
Name all 5 different cell arrangements:
- single
- Diplo
- spirilla
- strepto
- staphylo
What is strepto?
in chains
What is staphylo?
in clumps
What are endospores?
resistant, dormant cell triggered by
adverse conditions
Name 2 genera of bacteria that can produce endospores
Bacillus & Clostridium
Name all 4 different modes of nutrition in Organisms
- Photoautotroph
- Chemoautotroph
- Photoheterotroph
- Chemoheterotroph
Most bacterial species are what?
Chemoheterotrophs (like animals, fungi and some protists)
What do Chemoheterotrophs do?
they consume live/dead organic material to obtain organic compounds
(breakdown organic comp. for energy)
Some bacteria are also what?
Photoautotrophs (like plants and algal protists)
What are photoautotrophs capable of doing?
use light as an energy source
(produce organic comp. from inorganic comp. such as CO2)
Which 2 modes of nutrition are unique to prokaryotes?
Chemoautotrophs & Photoheterotrophs
Prokaryotic metabolism also varies with
respect to WHAT?
oxygen
What are the 3 different metabolisms concerning oxygen?
Obligate aerobes
Facultative anaerobes
Obligate anaerobes
Which prokaryotic metabolism is Poisoned by O2?
Obligate anaerobes
Which one will use O2 if present but can also grow by fermentation?
Facultative anaerobes
Which one REQUIRES O2 for cellular respiration?
Obligate aerobes
Where is E. coli commonly found?
in the lower intestine of vertebrates
(such as humans)
Where is B. subtilis commonly found
in the soil
This diversity stems from different WHAT?
different ENZYMES
What is the Aseptic technique?
a procedure to prevent infection from pathogens like bacteria and viruses. It involves applying strict rules during medical procedures to minimize the risk of contamination
Name 2 ways to culture bacteria (the ways)
- the streak method
- the lawn of bacteria
What does the streak method consist of?
used for E. coli & B. subtilis
used to ISOLATE individual bacterial colonies by diluting the sample across the plate, allowing for the growth of separate colonies originating from single bacterial cells.
What does the lawn method consist of?
uniform bacterial lawn covering the entire plate, which is useful for certain applications such as antibiotic sensitivity testing or phage susceptibility assays
There is another method (zig-zap streak/pattern), why use this strategy?
- decrease cell density gradually to isolate cells from one another
Give info for E. coli
1) cell shape
2) cell arrangement
3) gram stain (+ or -)
4) flagella or no flagella
5) colony shape
6) colony pigmentation
7) colony texture
8) colony reflection
9) colony transparency
1) bacillus
2) single
3) gram -
4) no flagella
5) circular
6) tan
7) smooth
8) glossy
9) translucide
Give info for B. subtilis
1) cell shape
2) cell arrangement
3) gram stain (+ or -)
4) flagella or no flagella
5) colony shape
6) colony pigmentation
7) colony texture
8) colony reflection
9) colony transparency
1) bacillus
2) strepto
3) gram +
4) no flagella
5) non-circular
6) white
7) rough
8) matte
9) opaque
Give info for S. aureus
1) cell shape
2) cell arrangement
3) gram stain (+ or -)
4) flagella or no flagella
1) coccus
2) staphylo
3) gram +
4) no flagella
Give info for S. volutans
1) cell shape
2) cell arrangement
3) gram stain (+ or -)
4) flagella or no flagella
1) Sprilillum
2) single
3) gram -
4) flagella
Which antibiotic targets DNA replication?
Norfloxacin (NOR)
Which antibiotic targets Protein synthesis?
Streptomycin (S)
Which 2 antibiotics target cell wall synthesis?
Penicillin (P) & Cefotaxime (CFX)
Where do you find E. coli?
in the gastrointestinal tract of humans/animals
Where do you find B. subtilis?
in the soil
Which one is sensitive to penicillin (E.coli or B.sub)?
B.subtilis sensitive
E. coli resistant
Do they have flagella (both)?
non-visible at 1000X
Which one can break down starch using amylase?
B. subtilis CAN breakdown starch using amylase
(E. coli can’t)
What is a bacterial colony?
mass of bacterial cells that have arisen from a single mother cell
