Fungal Microbiology Flashcards
Why do we culture fungi?
Identification
Phenotypical arrays
Specimen preservation
Physiological and biochemical studies
Drug resistance studies
Biotechnology
How do we identify microfungi?
Isolation (when possible)
Colony morphology
Micromorphology
Phenotype assays
Deposit in a culture collection
What are the key components of a culture medium?
A carbon source: often glucose/dextrose or fructose/mannose
A source of nitrogen: peptone, yeast extract, malt extract, amino acids, ammonium, nitrate compounds
Vitamins: thiamine B1 and biotin B7
Often selective inhibition of bacteria with antibiotics during isolation
What are ascomycetes naturally deficient in?
thiamine B1 and biotin B7
Where is agarose typically sourced from and why?
Red algae, most fungi cannot break down agarose
Which group can break down agarose?
Agarophytes
What are some common types of agar?
Tap water agar
Potato dextrose agar
Morel growth agar
What are hyphal characteristics?
Clamp connections
Hyphal width
Septation
Pigmentation
Cell wall thickness
Exudation
What does hyphomycete identification depend on?
Inferring conidiogenesis
What does conidiogenesis refer to?
How conidia (anamorphic spores) form on conidiophore cells
What are cells that give rise to conidia called?
Conidiogenous cells
What are the two main types of conidiogenesis?
Blastic
Thallic
What does septation precede in thallic conidiogenesis?
Septation precedes conidial formation
What are the types of thallic conidiogenesis?
Type I: thallic-arthric
Type VIII: thallic-solitary (holotallic)
When does septation happen during blastic conidiogenesis?
Septation happens with or after the formation of conidia
What are the main types of blastic conidiogenesis?
Holoblastic
Enteroblastic
Phialidic
Annelidic
What happens during type II holoblastic conidiogenesis?
Both cell wall layers participate in the formation of conidia
Forms a subset of conidia that can form smaller conidia
What are the subtypes of holoblastic conidiogenesis?
Type IIA: holosoloblastic, aleurospores
Type IIB: blastocantenate, blastoconidia
Type IIC: holopolyblastic, botryoblastic
Type IIC: holopolyblastic successive, sympodulospores
Where is the chain oriented in blastocantenate conidiogenesis?
The chain is oriented to the youngest conidia
What happens during type III enteroblastic conidiogenesis?
Only the inner cell wall layer of the conidiogenous cell participates in the formation of conidia and the outer cell wall is left with scars
What happens during blastic phialidic conidiogenesis?
Phialides are special conidiogenous cells that don’t change in length - the oldest conidia is at the top of the chain
The conidiogenous cell does not share any cell wall with the conidium
The conidiogenous cells keep producing phialoconidia and they form the cell walls for the next conidium while still in the mother cell
How can phialides produce conidia?
Either in chains (basipetal) or in heads
What is the annellation that blastic annellidic conidiogenesis leaves?
Each seceding conidium leaves a ring-like scar around the conidiogenous cell, which then grows on through the scare to produce the next conidium
How are yeasts identified?
Microscopic appearance
Sexual reproduction
Physiological features
Biochemical characteristics
What is included in yeast morphology?
Color and texture of colonies
Cell shape
Cell size
Budding/division type
Cell wall type
Inclusions (oils, glycogen granules)
What are the types of yeast budding?
Blastic-acropetal
Blastic-sympodial
Blastic-percurrent
Blastic-phialidic
Blastic-arthric
What are the physiological features of yeast?
The ability to ferment certain sugars anaerobically
The ability to grow aerobically with various compounds
Temperature - growth at cold temps
The ability to split fats
What are the biochemical features of yeast?
The types of cell wall structures
Type of ubiquinone involved in the mitochondrial respiration chain
