Stachybotrys Selective Agar

Cat. no. W173 Stachybotrys Selective Agar, 15x100mm Plate, 26ml 10 plates/bag


Hardy Diagnostics Stachybotrys Selective Agar is for use in the selective isolation of Stachybotrys from environmental samples.

This product is not intended to be used for the diagnosis of human disease.


Concerns have been raised about possible health problems due to human exposure to indoor mold growth. Toxigenic mold species in water-damaged buildings has promoted much of this concern. Contamination of indoor air by Stachybotrys spp. is thought to be rare, however, S. chartarum ( atra ) is prone to growth indoors. It is generally found on high cellulose content materials such as fiberboard, gypsum board, dust, and lint, where moisture has settled, or there is water damage due to excessive humidity, water leaks, condensation, infiltration, or flooding. (3,4,6)

Fungi have the potential to produce allergens, irritants, and in some cases potentially toxic substances (mycotoxins), which can induce an allergic response, cause asthma attacks, and irritate the eyes, skin, throat, and lungs or susceptible individuals. S. chartarum , may or may not produce toxins depending on several factors, including the specific fungal strain and the organic substrate it is metabolizing. Testing to conclusively identify Stachybotrys indoors is necessary since other common indoor molds can look similar to Stachybotrys (including Cladosporium, Aspergillus , Alternaria , and Drechslera ). (4,6,10)

Recovery of Stachybotrys chartarum ( atra ) from environmental samples can be difficult due to competition of more aggressive fungi, even on selective agar. In a study conducted by R.A. Billups, et al., Potato Dextrose Agar (PDA) showed Stachybotrys morphology more quickly than Cellulose Agar, Corn Meal Agar (CMA), and Malt Extract Agar (MEA). The study also included an evaluation of PDA with an antibiotic/antimycotic combination added to it, and concluded that this modified PDA effectively reduced the competition and allowed enhanced recovery of Stachybotrys spp. when incubated at 35ºC. (9)

Hardy Diagnostics Stachybotrys Selective Agar contains potato infusion, dextrose, and selective agents. Potato infusion provides a nutrient base for growth of most fungi, dextrose serves as a growth stimulant, and selective agents are added for selective isolation of Stachybotrys spp.


Ingredients per liter of deionized water:*

Dextrose 20.0gm
Potato Infusion 4.0gm
Selective Agents 100.0mg
Agar 15.0gm

Final pH 5.6 +/- 0.3 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.



Specimen Collection: It is important to take proper cautions when cleaning and sampling mold contaminated areas, in order to limit exposure to mold and mold spores. It is recommended that while cleaning or sampling an area potentially contaminated with fungi that one wears a N-95 respirator, gloves, and goggles. Consult listed references. (3,4,10)

1. Allow media to equilibrate to room temperature, and the agar surface to dry before inoculating.

2. Using a needle, loop, or swab remove a small amount of mature growth from the area to be cultured. Inoculate and streak the sample as soon as possible after collection.

3. If the specimen to be cultured is on a swab, roll the swab over a small area of the agar surface. Streak for isolation with a sterile loop. If the specimen is collected on a loop or needle, inoculate the plate with fungi in two or three distinct places by pressing the inoculum onto the agar surface.

4. Incubate plates in an inverted position. Consult listed references for more information on incubation time and temperature. (8-10) Once inoculated, media can be incubated aerobically at 25-35ºC. with increased humidity for four weeks or longer. Hardy Diagnostics MycoSeal™ product (Cat. no. SS9225) may be used to seal the plates to keep moisture from evaporating from the plated media, while still allowing atmospheric circulation.

5. Examine plates for typical colonial and hyphal morphology and color.

6. Growth observed on Stachybotrys Selective Agar should be examined microscopically to confirm identification.


Stachybotrys species are moderately rapid growers, have a powdery texture, and can range in color from white, pink, orange or black on the surface, to pale, orange, pink or black on the reverse. Stachybotrys chartarum ( atra ) is prone to growth indoors and usually produces brown or black colonies on the surface and on the reverse. (5,6)

Identification of fungi is performed by observing various aspects of colony morphology, characteristic microscopic structures, rate of growth, media which supports the organisms growth, and source of the specimen. Yeasts are identified by various biochemical tests. Consult the listed references for information regarding the identification and further testing of fungi and yeast cultures. (5,6,10)



Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Stachybotrys chartarum
ATCC ® 9182
G Up to 14 days 25-35° Aerobic Positive; growth
Aspergillus brasiliensis
formerly A. niger
ATCC ® 16404

G Up to 14 days 25-35°C Aerobic Negative; no growth
Escherichia coli
ATCC ® 25922
B Up to 14 days 25-35°C Aerobic Negative; no growth

User Quality Control

Physical Appearance

Stachybotrys Selective Agar should appear clear, with no precipitate or debris, and light amber in color.

S. chartarum growing on Stachybotrys Selective Agar

Stachybotrys chartarum (ATCC ® 9182) growing on Stachybotrys Selective Agar (Cat. no. W173). Incubated aerobically for 14 days at 30ºC.

A. niger inhibited on Stachybotrys Selective Agar

Aspergillus brasiliensis formerly A. niger (ATCC ® 16404) growth inhibited on Stachybotrys Selective Agar (Cat. no. W173). Incubated aerobically for 14 days at 30ºC.


1. Jarvis, Bruce B., W.G. Sorenson, E.L. Hintikka, M. Nikulin, Y. Zhou, S. Wang, S. Hinkley, R. A. Etzel and D. Dearborn. 1998. Study of Toxin Production By Isolates of Stachybotrys chartarum and Memnoniella echinata Isolated During A Study of Pulmonary Hemosiderosis In Infants. Applied and Environ. Microbiology ; 64:3620-3625.

2. Tuomi, T., K. Reijula, T. Johnsson, K. Hemminki, E.L. Hintikka, O. Lindroos, S. Kalso, P. Koulia-Kahkila, H. Mussalo-Rauhamaa and T. Haahtela. 2000. Mycotoxins In Crude Building Materials From Water-Damaged Buildings. Applied and Environ. Microbiology ; 66:1899-1904.

3. New York City Dept. of Health. 1993. Guidelines on Assessment and Remediation of Stachybotrys atra In Indoor Environments. p. 35-42.

4. California Dept. of Health Services. 2000. Misinterpretation of Stachybotrys Serology. Internet: /ps/deodc/ehib/EHIB2/topics/Serologyf2.htm. p. 1-4.

5. St. Germain, Guy, B.S., Richard Summerbell, Ph.D. 1996. Identifying Filamentous Fungi . Star Publishing Company, Belmont, CA.

6. Pinto, Michael A., Ph.D., CSP. 2000. An Overview of Stachybotrys Mold. p. 1-6. Wonder Makers Environmental. Internet: .

7. Billups, R.A., J.E. Parent, K.S. Fallon and P.S. Warden. 2001. Application of Novel Media For the Improved Recovery of Stachybotrys chartarum From Environmental Samples. 2nd NSF Int'l Conference on Indoor Air Health. p.1 (Abstract). Miami Beach, FL.

8. Billups, R.A., Kristen S. Tilton, Ph.D., and Paul S. Warden. Identification of Stachybotrys chartarum Utilizing Various Media and Two Temperature Settings. 1st Annual NSF Int'l Conference on Indoor Air Health. p.1 (Abstract).

9. Billups, R.A., K.S. Tilton, Ph.D., and J.S. Warden. 1999. Enhanced Recovery of Stachybotrys chartarum From Environmental Samples. American Industrial Hygiene Conference and Exposition (AIHCE). p.1 (Abstract). Toronto, ON.

10. U.S. Environmental Protection Agency. 2002. "A Brief Guide to Mold, Moisture and Your Home." Internet: /iaq/molds/moldguide.html.

ATCC is a registered trademark of the American Type Culture Collection.