2. Identification of bacterial cells Flashcards
(47 cards)
name two culture collections across the world
American type culture collection (ATCC)
national collection of type cultures (NCTC) -> public health england
what does NCIMB stand for
national collection of industrial, food and marine bacteria
how many classes of bacteria are there
4
which class of bacteria: 1. can cause severe disease?
class 3
which class of bacteria: 2. is safe to use (non-pathogenic)
class 1
which class of bacteria: 3. is incurable
class 4
how many strains of class 4 bacteria are there
none
name a class 4 virus
ebola
what are class 2 bacteria
cause mild, treatable disease, can be worked with in the lab
how does Gram staining work
crystal violet applied to samples, if Gram-positive, crystal violet will bind tightly to peptidoglycan and following an ethanol wash, be stained purple. (positively purple)
if not, following ethanol wash, and counter staining with safranin, will stain pink
(negative pink)
we can identify shapes based on morphology, name some shapes
cocci (circle)
rods
spiral
corkscrew
how do we measure oxygen tolerance
inoculate broths with bacterium, note location of growth
where will obligate aerobe’s grow in broth medium, what does this show?
at the top
- preference for oxygen
where will obligate anaerobe’s grow in broth medium, what does this show?
growth at the bottom
- no tolerance for oxygen
where will aerotolerant anaerobe grow in broth medium, what does this show?
bacterium distributed throughout, tolerance for presence and absence of oxygen
how can we identify the presence of endospores
malachite green stains bacteria black and endospores appear white
what type of cells are endospores found in
Gram positive bacteria only
where do endospores form under, what does this mean?
unfavourable conditions
they are highly resilient to heat, drying, radiation and chemicals
how do you remove endospores
a strict course of antibiotics taken for months to eradicate further infections
describe the structure of endospores (2)
- contain calcium dipicolinate
2. have special proteins to protect their DNA.
how can cell motility be measured
place a sterile needle containing the bacterium colony into sloppy agar. this medium contains a dye which stains cells red.
non-motile bacterium will remain in one place, motile bacterium will move around the medium.
what does catalase convert
toxic hydrogen peroxide into water and oxygen
how do you perform the catalase test, what would a positive result show?
- adding a bacterial culture to a bubble of hydrogen peroxide
- if catalase is present, bubbles of oxygen will be produced
what does kovac’s reagent test for
the presence of cytochrome C and oxidase
