CMA Mold Identification & Types 3 — Questions and Answers
Question 1: Which mold is classified as a thermophilic organism and can grow at temperatures above 45°C?
- Stachybotrys chartarum
- Aspergillus fumigatus (Correct answer)
- Cladosporium herbarum
- Alternaria alternata
Correct answer: Aspergillus fumigatus
Aspergillus fumigatus is thermophilic and can grow at temperatures up to 55°C, making it a concern in compost piles and HVAC systems.
Question 2: In mold taxonomy, what does the term 'xerophilic' mean?
- Thrives in high-humidity environments
- Capable of growing at very low water activity (Correct answer)
- Requires freezing temperatures to sporulate
- Grows only on wood substrates
Correct answer: Capable of growing at very low water activity
Xerophilic molds can grow at very low water activity (aw), meaning they tolerate dry conditions better than most fungi.
Question 3: Fusarium species are most commonly associated with which indoor substrate?
- Painted concrete walls
- Carpets and water-damaged flooring materials (Correct answer)
- Metal ductwork
- Glass window panes
Correct answer: Carpets and water-damaged flooring materials
Fusarium is commonly found on water-damaged carpets and flooring and is also an important plant pathogen and emerging human pathogen.
Question 4: What is the primary difference between mold and mildew as used in the field?
- Mildew is a type of bacteria; mold is fungal
- Mildew typically refers to powdery or downy plant pathogens or surface fungi; mold refers to invasive fungal growth (Correct answer)
- Mold grows outdoors only; mildew grows indoors only
- There is no scientific difference; they are synonymous
Correct answer: Mildew typically refers to powdery or downy plant pathogens or surface fungi; mold refers to invasive fungal growth
In common and professional usage, 'mildew' typically refers to superficial, powdery fungal growth on surfaces or plants, while 'mold' denotes deeper, invasive fungal colonization.
Question 5: Chaetomium is particularly significant in building assessments because it indicates what condition?
- Extremely high outdoor spore counts
- Prolonged water intrusion or chronic wetting of cellulosic materials (Correct answer)
- Normal background fungal levels
- Presence of sewage contamination only
Correct answer: Prolonged water intrusion or chronic wetting of cellulosic materials
Chaetomium requires prolonged moisture on cellulosic substrates like drywall paper and cardboard, making its presence a strong indicator of chronic water damage.
Question 6: Which analytical method allows identification of mold genera from air samples by examining spore morphology under a microscope?
- PCR (polymerase chain reaction) analysis
- Spore trap analysis (e.g., Zefon Air-O-Cell) (Correct answer)
- ATP bioluminescence testing
- pH indicator strips
Correct answer: Spore trap analysis (e.g., Zefon Air-O-Cell)
Spore trap sampling collects airborne particles on a sticky surface that is then examined microscopically to identify and count mold spores by morphology.
Question 7: A mold assessor finds pink-pigmented colonies on a water-damaged ceiling tile. Which genus is most likely?
- Stachybotrys
- Fusarium (Correct answer)
- Aspergillus niger
- Ulocladium
Correct answer: Fusarium
Fusarium species frequently produce pink, salmon, or lavender pigmentation and are found on water-damaged building materials.
CMA Mold Identification & Types 3
Which mold is classified as a thermophilic organism and can grow at temperatures above 45°C?