Culture Dependent Methods

Question 1

solation of bacteria and fungi into ___form is the best way to study and characterize
bacterial cultures.

Answer 1

pure

Question 2

For bacteria, pure culture isolation is usually accomplished by

Answer 2

preading a dilution
containing microorganisms on a solid medium so that a single cell or a colony-forming unit
occupies a well-isolated portion of the agar surface.

Question 3

Cultures consisting of single type
colonies are

Answer 3

pure cultures

Question 4

among the
culture-dependent techniques used for this purpose

Answer 4

streak plating
spread plating

Question 5

s, are present in almost all natural environments

Answer 5

fungi

Question 6

colony types of nonfilamentous form

Answer 6

yeast

Question 7

One of the best techniques in visualizing fungal structures as they develop is the

Answer 7

slide culture technique

Question 8

Several reagents are added to the growth on a slide to
rehydrate tissues, provide contrast between parts and background and detect certain
biomolecules such as

Answer 8

starch

Question 9

agar plate for fungi

Answer 9

potato dextrose agar plate

Question 10

reagents for fungi stianing

Answer 10

lactophenol cotton blue

Question 11

positive stain

Answer 11

methylene blue

Question 12

negative stain

Answer 12

nigrosin

Question 13

bacterial sample

Answer 13

s. marcescens

Question 14

mold culture

Answer 14

a. niger

Question 15

. Prepare sterile __ plates and draw four quadrants at the base to guide
streaking.

Answer 15

nutrient agar

Question 16

5. Incubate the plates in an ___ position at ___˚C for 48 hrs.

streak plating

Answer 16

inverted
37oC
48 hours

Question 17

. Draw about ___ ml from a 24-hr broth culture using a pipette with sterile
blue tips, and deposit into a sterile NA plate for spread plate

Answer 17

0.1ml

Question 18

Using a sterile ___, spread the inoculum evenly over the
surface of the agar and let stand for few minutes with the lid ajar to dry.

Answer 18

L-rod spreader

Question 19

1. Prepare a bacterial smear.
2. Stain the smear with methylene blue for 1 min.
3. Wash with water and blot dry. Focus under the OIO.
4. The microorganisms should be colored dark blue to violet with a bright
   background.
5. Answer item 3-4 in the worksheet.

what staining

Answer 19

positive staining

Question 20

Using an inoculating loop, apply a small loopful of bacteria to one end of a
clean microscope slide.
2. Add 1 to 2 loopful of nigrosine dye to the bacteria and mix thoroughly.
3. Spread the mixture over the slide by laying over a second glass slide onto
the drop and then pulling slides away from each other. Air dry only.
4. Focus under the OIO.

whwat staining

Answer 20

negative staining

Question 21

setup of slide culture technique

Answer 21

clean filter paper inside the petri dish, then a sterile
bent glass rod on top of the filter paper. Secure a clean slide and place it over
the bent glass rod. Autoclave right-side up.

Question 22

Aseptically cut a block of what media (and what size) for slide culture

Answer 22

PDA (1cm^2)

Question 23

Repeat steps 3-4 using Rhizopus as the inoculum. Incubate at __3C for 48 hrs

Answer 23

30

Question 24

Place a drop of ____ ___ ___on a clean slide and lay over the
coverslip from the set up. Observe under OIO.

Answer 24

lactophenol cotton blue

Question 25

view module 3 results

Answer 25

+1

Question 26

Name a general-purpose medium used for isolation and cultivation of bacteria. indicate the purpose/uses/functions of the medium and enumerate the components.

Answer 26

Nutrient agar (NA) is generally used for streak, spread, pour, slant, etc. In general, its purpose is to provide a solid surface for cultivation to create separate colonies in either pure or mixed culture. In addition, this provides nutrients for non-fastidious bacteria that can also be used in stocking cultures. The components of NA are peptone, beef extract, sodium chloride, agar, and distilled water (these components may differ according to the manufacturer).

Question 27

4. Compare/contrast principles of positive and negative staining. (3 pts.)

Answer 27

Positive staining is coloring microorganisms on a clear or bright background using basic dyes such as crystal violet, methylene blue, and safranin. Direct staining enables easier viewing of cellular structures and characteristics. Additionally, heat fixation is required for this staining. On the other hand, negative staining colors the background surrounding the cells using acidic dyes with a negative charge like nigrosin and Indian ink creating a silhouette effect useful for visualizing structures difficult to stain directly. In this staining, heat fixation is avoided because it can damage cellular characteristics.

Question 28

aspergillus septate/aseptate

Answer 28

septate

Question 29

asexual spore of aspergillus

Answer 29

conidia

Question 30

phylum of aspergillus

Answer 30

ascomycota

Question 31

is rhizopus septate/aseptate

Answer 31

aseptate

Question 32

asexual spore of rhizopus

Answer 32

sporangia

Question 33

phylum of rhizopus

Answer 33

zygomycota

Question 34

. Give two other reagents used in microscopic examination of fungi. Explain their purposes.

Answer 34

Other common reagents used in the microscopic examination of fungi are Schiff's Reagent and Congo Red

Question 35

often used with periodic acid, detects polysaccharides in fungal cell walls by reacting with aldehyde groups to produce a vivid magenta color, making it especially useful for identifying fungi in tissue samples during histopathological analysis.

Answer 35

schiff's reagent

Question 36

binds specifically to chitin and cellulose in fungal cell walls, allowing clear visualization of yeasts and filamentous fungi under the microscope. It often produces a bright orange fluorescence, making it a valuable tool for rapidly detecting fungi in clinical specimens and culture preparations.

Answer 36

congo red

Question 37

Name a general-purpose medium used for isolation and cultivation of fungi. Indicate the purpose/uses/functions of the medium and enumerate the components

Answer 37

SDA

Question 38

is a widely used medium for isolating and growing fungi. It serves a general purpose in fungal culture and inhibits bacterial growth due to its high acid concentrations. The components of SDA are peptone, dextrose, agar, and water with an acidic pH of around 5.6.

Answer 38

saboraud dextrose agar

Question 39

SDA is composed of

Answer 39

peptone dextrose agar water

Question 40

pH of SDA

Answer 40

5.6