Morphology of Yeasts and Molds Flashcards
other name for pseudomycelium
false mycelium or sprout mycelium
Pseudomycelium can be demonstrated when yeasts are grown under reduced ___conditions
oxygen
is a chain of cells that resemble a small mycelium
pseudomycelium
Yeast reproduces by ____.
budding
Sometimes a bud starts forming a new bud before separating from the parent cell.
This results in the formation of branched or unbranched chains of buds, called
pseudomycelium
is a vegetative structure that gives rise to arthrospore or blastospore.
true mycelium
is an asexual spore (conidium) formed from a preexisting hypha.
arthrospore
is still an asexual spore formed following the marked enlargement of a part of a cell before separation by a septum
blastospore
Reproduction by yeasts is mainly by asexual means such as by
budding
fission
mycelia consisting of septate hyphae
an outgrowth develops from the parent cell and eventually separates as a daughter cell.
budding
the parent cell simply divides and develops into two identical daughter cells.
fission
seexual reproduction, if it occurs, is usually by
ascopore
basidiospore
some spores are ___ (imperfect), lacking sexual phase or have not yet discovered/established
anamorphic
are filamentous or multicellular fungi that are commonly found as contaminants from the air, and as constituents of the normal flora in nature.
molds
molds grow as filaments called
hyhpae
hyphae is collectively called
mycelia
vegetative structure of mold
thallus
he hyphae that make up the thallus (body/vegetative structure) of the mold can be either
branched
unbranched
___branching of the hyphae is uncommon, but does exist in a few species
dichotomous
Dichotomous branching of the hyphae is uncommon, but does exist in a few species like in what speies
allomyces
galactomyces geotrichum
Moreover, the mycelium can also be either be
septated
non-septated
discernible crosswalls
septa
Crosswalls have small ___ through which the cytoplasm is continuous throughout the hyphae to allow exchange of cytoplasm or organelles.
pores
Crosswalls have small pores through which the cytoplasm is continuous throughout the hyphae to allow
exchange of cytoplasm
organelles
. In septated fungi, branches are often situated immediately behind a ___.
septum
Non-septated hypha tends to be continuous along the whole length of the filament that can be either ____ or ___
coenoycyic
multinucleated
Since the hypha is a structural unit, the ___ imparts color, texture, and overall appearance to the mold colony.
mycelium
Molds that possess melanin pigments in their cell walls are described as
dematiaceous
On the other hand, molds that do not produce pigments in their cell walls are described as
hyaline
hyaline means
transparent or transluscent
he mycelia can be differentiated as
submerged
aerial
fertile
are those that penetrate and anchor the thalli in the substrate and absorb the nutrients.
submerged mycelia
are those that grow above the substrate
aerial mycelia
are aerial mycelia that bear the reproductive structures such as conidia or sporangia
fertile mycelia
Fertile mycelia are aerial mycelia that bear the reproductive structures such as
conidia
sporangia
Molds also form various types of reproductive spores. Two kinds of asexual spores are seen in molds, the
sporangiospores
conidia
are spores that form within a sac called a sporangium.
sporangiospores
Sporangiospores are spores that form within a sac called a
sporangium
he sporangia are attached to stalks called
sporangiophores
are spores that form on specialized hyphae called conidiophores.
conidiophore
conidia are spores that form on specialized hyphae called
conidiophore
If the conidia are small, they are called
micronidia
Large multicellular conidia are known as
macronidia
There are four types of conidia
phialospore
blastoconidia
athrospore
chlamydospore
conidia are produced by vase-shaped cells called phialides
phialospore
conidia are produced from budding of preexisting conidia)
blastoconidia
onidia formed by separation from preexisting hyphal cells)
arthrospore
spores are large, thick walled, round, or irregular structures formed within or on the ends of a hypha
chlamydospore
___ reproduction in molds involves the union of compatible nuclei.
sexual
sexual spores result from a mating between two different organisms or hyphae which include the
oospore
zygospore
ascospore
basidiospore
produced when male gametes enter a large spherical cell called oogonium and fertilized the egg within
oospore
formed by union of two h protrusions from neighboring hyphae of two different strains
zygospore
produced enclosures, which may be oval sacs or elongated tubes called asci
ascospores
produced externally on club-shaped bodies called basidia
basidiospores
s a technique used to identify yeasts and other fungi by growing them on a plate and examining them under a microscope
dalmau plate method
dalmau plate method is also known as
corn meal agar (CMA) technique
a coverslip is placed on the inoculatd place to make a ___ condition
microaerophilic
are eukaryotic organisms belonging to
one big group
fungi
One-celled and some
types are
multicellular. Assume
complex organization
as filamentous
organisms
fungi
fungi Grows as colonies of
___ appearance
forming networks
called mycelia
leathery
Unicellular
* Non-filamentous
* Reproduction carried out by budding/fission
yeast
- Multicellular forming structures called hypha.
molds
is a fungal infection caused by an imbalance of healthy bacteria and yeast in your body.
candidiasis
s an antifungal metabolite produced by the fungus Penicillium brevicompactum. It was initially discovered for its antifungal properties, but later research revealed its potential as a cholesterol-lowering agen
compactin
compactin s an antifungal metabolite produced by the fungus ___ ___. It was initially discovered for its antifungal properties, but later research revealed its potential as a cholesterol-lowering agen
penicillum brevicompactum
compactin s an antifungal metabolite produced by the fungus Penicillium brevicompactum. It was initially discovered for its antifungal properties, but later research revealed its potential as a ___-lowering agen
cholesterol
Techniques and Tools in the Study and
Identification of yeasts and molds
Slide culture
* Dalmau plate
* Potato dextrose agar
* Sabouraud dextrose agar
* Czapek-Dox agar
* Molecular methods
are non-coding sections of DNA located between the conserved coding regions of ribosomal RNA (rRNA) gene
internal transcriber spacer
is widely used for identifying and classifying fungi because these regions exhibit significant variability, making them excellent markers for phylogenetic studie
fungal ITS sequencing
yeast culture
saccharomyces sp
stains used
5% malachite green
safranin
dalmau plate method
Make a single streak of a yeast culture at the ___ of a pre-poured PDA plate.
center
. With flame-sterilized forceps, put an autoclave-sterilized ___ ___ on top of the streak.
dalmau plate method
cover slip
Exhaust the air bubbles trapped underneath the cover slip by carefully ____ the
coverslip with flame-sterilized forceps.
dalmau plate method
pressing
dalmau plate method
s. Incubate the plate in an inverted posiAon at ___°C
for ___ h.
30oC for 48h
Remove the ___ of the plate and mount the plate directly on the microscope.
AlternaAvely, carefully remove the coverslip and place on a clean glass slide with a droplet
of water and observe under the microscope.
dalmau plate method
lid
Dalmau plate method
Observe for the presence of true or
pseudomycelia under what objectives
LPO or HPO
Streak the yeast for isolaAon separately on PDA plates. Incubate as indicated above
.
2. Observe colony morphology on PDA (not the Dalmau plate) every day for one __.
cultural characteristics
week
what cultural characteristics are observed
surface
edge
margin
color
texture
different surface of colony
smooth
concentric
contoured
wrinkled
view different surface of colony
+1
different edge/margin of colony
entire
lobate
filamentous
curled
undukate
view different margin of colony
+1
different consistency of colony
dry
butyrous
viscid
optical features of colony
transparent
opaque
transluscent
opalescent
elevation of colony
flat
raised
convex
umbonate
crateriform
pulvinate
. Prepare a wet mount by suspending a small amount of yeast from PDA plates in a drop
of ___ on a slide. Place a cover slip on top of the mount
asexual reproduction
water
Examine the preparaAon under __. Take note of the following features:
mode of asexual reproduction
HPOa
different shape of vegetative cell of yeast
spheroidal
subglobose
ellipsoidal
ovoid
cylindrical
elongate
apiculate
most visible structures in a cell yeast
granules
vacuoles
method of aseuxal reproduction of yeast
budding
The primary method of asexual reproduction in yeast is called
budding
- Grow culture on PDA for __days (or unAl next meeAng) at 25°C.
sexual reproduction
3-5
. With a flame-sterilized loop, obtain a small amount of culture from the PDA. Spread it
thinly on the glass slide with a droplet of water. Air dry and heat-fixed smear by passing
the slide three Ames on the flame of an __ lamp.
alcohol lamp
Cover smear with absorbent paper/paper towel to prevent accumulaAon of arAfacts.
Flood smear with ___ ___ and stain for 30 min or steam the slide on a staining
pan for 7 min. Ensure that the stain does not dry up by checking from Ame to Ame.
malachite green
: If steaming of the slide will be performed, do it under a fume hood fume of malachite
green is ___.
carcinogenic
Remove the absorbent paper/paper towel with forceps and wash thoroughly with tap
water. Remove all excess water by allowing the slide to stand in a ____ posiAon for a
few seconds
vertical
. Counterstain with ___ for 30-60 sec. Wash the slide and blot dry. Examine under
OIO.
safranin
Ascospores (or basidiospores, if present) should appear __ while the vegetaAve
cells should be __ ___.
green
pink red
Note: Sexual reproductioon may not be readily observed in ___ cultures. Incubate for
more than one week to confirm ability to form ascospore or basidiospore.
young
. Remove the cover of the plate. Invert the boMom part of the plate containing the prepoured medium. With a flame-sterilized needle, do a ___ ___ ____ of the
mold culture on the center of the PDA plates. Incubate in inverted posiAon at 30-35
degrees Celsius for 1-7 days
sequential point inoculation
. Remove the cover of the plate. Invert the boMom part of the plate containing the prepoured medium. With a flame-sterilized needle, do a sequenAal point inoculaAon of the
mold culture on the center of the PDA plates. Incubate in inverted posiAon at 30-35
degrees Celsius for __ days
1-7 days
Rhizopus sp. and Mucor sp. grow well on PDA. Store the inoculated plates with
Rhizopus sp. and Mucor sp. in the refrigerator aHer the hour of incuba?on to avoid
___.
overgrowth
possible identity of mold
rhizopus sp.
mucor sp.
. Sterilize a Petri dish containing the following: filter or paper towel as boMom lining, a
bent glass rod/toothpick, coverslip and glass slide.
what method
slide culture method
- Pour ___ water on the plate unAl the filter or paper towel is property
aterile
Prepare an agar block by pouring a thin layer of PDA (about ___mm thick) into a sterile
plate. Slice the solidified PDA with a flame-sterilized wire approximately 1-cm square
blocks. LiX the agar block and deposit on the center of the glass slide inside the plate
prepared in step 1
3-5mm thick
Inoculate all four upper edges of the PDA block by touching the __ culture using
sterile wire needle and deposiAng small amounts into the block.
mold
With flamed-sterilized forceps, place the autoclaved ___ slip on the inoculated PDA
block.
cover
Remove slide culture from the plate. Wipe dry the moisture at the boMom part of the
slide and examine the agar block under ___ to ___. O
LPO to HPO
character of hyphae
septate
non septate
aerial or submerged
Character of fruiAng body
color
position
arrangement
nature of spore bearing hyphae
enlarged tip
branched tip
branched
details of spore
color
shape
septations
presence of vegetative structures such as
stolons
rhizoids
re root-like structures in mold that anchor the mold to its food source
rhizoids
a horizontal hypha that helps the mold spread and reproduce asexuall
stolon
Prepare a wet mount of the slide culture. If a semi-permanent mount is desired,
carefully liX the cover slip of the slide culture and deposit on a slide 1 to 2 drops of
lactophenol
Adsorb excess mounAng fluid with clean filter or Assue paper and seal the
sides of the cover slip with nail polish or ___.
paraffin
width of yeast
1-5um width
shape of yeast
egg shaped, elongated, or spherical
what are locomotory organelles of yeast
n/a
yeast is identified by ___ or ___
bud or bud scars
After the bud detaches from the parent cell, it leaves a mark known as a
bud scar
morphology of yeast
cell wall
periplasm
plasma membrane
protoplasm
nucleus
peroxisome, golgi, ER
ribosome, mitochondria
vacuoles
secretory vesicles
mold is a ___ fungi
filamentous
two parts of thallus
mycelium
spores
resistant, resting dormant cells are called
spores
spores on germination puts out “___ ___”
germ tube
is a small, tube-like outgrowth that extends from a germinating spore.
germ tube
elongate to form hyphae
germ tubes
network of branched htphae
mycelium
morphology of molds
hyphae with outer tube like cell wall
cavity of hyphae is called
lumen
cavity of hyphae (lumen) is filled with
protoplasm
double layered membrane between cell wall and protoplasm
plasmalemma
mold cell wall is made up of
matrix + microfibrils
growth of fungal hyphae
growth at ___ end
distal end
growth of fungal hyphae
division by ____ formation
cross wall formation
growth of fungal hyphae
____ streaming
protoplasmic streaming
growth of fungal hyphae
cross wall grow ___
inwards
growth of fungal hyphae
incomplete septum with central ___
pores
growth of fungal hyphae
cell division followed by ___
karyogamy
This step involves the fusion of these distinct nuclei from the two parent mycelia
karyogamy
forms of fungal hyphae
coenocytic
monokaryotic
septate dikaryotic or multinucleated cell
non septate cell wall
coenocytic
septate uninuclated cell
monokaryotic
molecular method of determining fungi
using PCR
semisynthetic growth medium, has sodium nitrate, sucrose, salts
czapek dox agar (CDA)
to cultivate and identify fungi
low pH
high conc. of dextrose
SDA AGAR
is more commonly used for a broad range of fungi, especially yeasts and molds
SDA
is tailored for specific fungi like Aspergillus and Penicillium.
CDA
Contains dextrose (glucose), peptone, and agar.
pH: Typically around 5.6, which favors fungal growth and inhibits many bacteri
Sabouraud Dextrose Agar (SDA)
types of fungal mycelia
submerged
reproductive
reproductive fungal mycelia is ___
protrude from media
vegatative fungal mycelia is __ in the medi
asubmerged
hat method minimizes disturbance
slide culture method
also called as CMA method
dalmau plate method
CMA means
cornmeal agar
made from potato extract aand dextrose, provides nutrients and carbohydrates, low pH
potato dextrose agar
shape of yeast specimen
ovoid or ellipsoidal
lighter, clear areas within the cells
vacuoles
lighter, clear areas within the cells
granules
yeast surface, edge, color, and texture
creamy white
smooth
entire
mucoid or creamy
In the picture above, there are some cells that are stained green. A sexual spore of a yeast is called
ascospore
read the results in worksheet
+1
- What is the purpose of the cover slip in Dalmau plate?
The purpose of using a coverslip in the Dalmau plate is to depict chlamydospores and other structures. Utilizing this reduces oxygen tension, aids in focusing under a microscope, and protects the microscope’s objective from contamination. Placing a coverslip ensures proper viewing of the specimen allowing the observer to see the growth pattern, hyphae, and other cellular components under a microscope.
- How is Schizosaccharomyces morphologically different from Saccharomyces?
Schizosaccharomyces and Saccharomyces differ in terms of cell shape, cell wall, and mode of reproduction. Schizosaccharomyces are usually rod-shaped and reproduce by fission (S.pombe), and the cell wall contains a unique component called pseudonigeran in addition to β-glucans. Whereas Saccharomyces is spherical or oval and reproduce by budding (S.cerevisiae) and their cell wall primarily consists of β-glucans and chitin.
- Discuss the principle of using PDA plates in studying yeast cultures.
Potato Dextrose Agar (PDA) is a medium used for the cultivation and study of yeast cultures due to its ability to provide the needed nutrients for fungal growth. For its composition, potato infusion serves as its nutrient base, while dextrose is considered as its carbohydrate source to stimulate yeast metabolism and proliferation. Additionally, PDA is often adjusted to have 3.5 pH using tartaric acid and the addition of antibiotics like chloramphenicol is used to inhibit bacterial proliferation while allowing fungi to thrive. Thus, PDA is ideal to isolate and enumerate yeast due to its capacity to aid in fungi sporulation.
- Why is malachite green used in ascospore staining?
Malachite green is used in ascospore staining since it has properties that make the ascospore readily take up its pigment. Unlike vegetative cells, sexual spores can take up malachite green by applying heat to the sample. Malachite green penetrates the tough outer layer of ascospores, which are resistant to staining under normal conditions. Thus, this dye provides a good contrast between the ascospores and vegetative cells for easier microscopic examination and visualization.
- What is the significance of having asexual and sexual modes of reproduction?
- What is the significance of having asexual and sexual modes of reproduction?
- What other characteristics should be used to accurately identify yeasts?
Other than using the microscope to observe its morphology (cell shape, budding patterns, presence of hyphae, color, etc.), just like what we did in this worksheet, there are other ways of accurately identifying the characteristics of yeasts. Some include; the usage of sugar fermentation tests and assimilation reactions to determine their metabolic capabilities. Another one is to possibly use Germ tube tests, wherein it is useful for identifying specific species Candida. Another is to use modified media such as chromogenic media tools like CHROMagar Candida help differentiate species based on color reactions. Additionally, the use of molecular sequencing, particularly MALDI-TOF, provides precise identification through genetic analysis.
- What is the reason for inverting the bottom part of the plate during point inoculation of a mold?
Inverting the bottom part of the plate during point inoculation of the mold prevents condensation droplets from the lid from dripping onto the agar surface. Should these droplets fall onto the inoculated area, they could disrupt the growth pattern and potentially contaminate the culture. Further, when incubated in the normal position, water from the media evaporates, causing media dryness and colony mix-up.
However, there are instances where the incubation of plates is done right-side up. In the laboratory activity, the plate used for slide culture set-up is incubated with the lid facing up. The upright position ensures proper gas exchange, avoiding invasive growths on the lid. Anaerobic strains are also incubated right-side up to allow space between the dish and the lid for gas exchange, removing oxygen. In this scenario, should the dish be incubated upside down, the condensation may act as an insulator, preventing gas exchange.
- What will happen if you wet the agar block in the slide culture set-up?
The slide-culture set-up allows microscopic observation of fungal structures on a small agar block. Careful control of the moisture level promotes healthy growth and sporulation of the specimen. If the agar block becomes wet in the slide culture set-up, it will be overly saturated with water, disrupting growth due to alterations in the controlled environment. An environment too wet for optimal development may lead to poor sporulation and difficult specimen observation. Excess water swells the specimen’s morphology, distorting it. Many specimens require specific conditions to produce spores; therefore, excessive moisture inhibits spore formulation. Furthermore, a very wet agar may encourage the growth of unwanted bacteria, further complicating the process and observation. ________________________________________
- What are the advantages of using slide culture technique over wet mount technique for studying molds?
The considerations in using slide culture to wet mounts for studying molds opens preservation of the fragile fungal structures (e.g. conidia) by direct growth on the slide different to the distortive behavior of wet mount preparation. The direct growth minimizes artifacts during sample transfer. Slide culture has a clearer visualization of undisturbed fungal morphology; thus, it is more reliable in terms of studying molds.
- What other morphological characteristics should be used in identifying molds?
The standard structures studied in molds are conidia, conidiophores, metulae, vesicle, sterigma, and its mycelia. However, inferring these characteristics, hyphal features, spore producing structures, spore morphology, colony appearance, and specialized structures should be used in identifying molds as it can create accurate interpretations in deducing molds.
