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Actinophrys sol Ehrenberg


Product category
Chromalveolata, Stramenopiles, Actinophryidae
Type strain
Isolation source
Brackish pond water, Shukkei-en Garden
Geographical isolation
Japan; Hiroshima
Product format
Storage conditions
-80°C or colder for 1 week, vapor phase of liquid nitrogen for long-term storage
Mission Collection Item
This is a Mission Collection Item.


ATCC determines the biosafety level of a material based on our risk assessment as guided by the current edition of Biosafety in Microbiological and Biomedical Laboratories (BMBL), U.S. Department of Health and Human Services. It is your responsibility to understand the hazards associated with the material per your organization’s policies and procedures as well as any other applicable regulations as enforced by your local or national agencies.

ATCC highly recommends that appropriate personal protective equipment is always used when handling vials. For cultures that require storage in liquid nitrogen, it is important to note that some vials may leak when submersed in liquid nitrogen and will slowly fill with liquid nitrogen. Upon thawing, the conversion of the liquid nitrogen back to its gas phase may result in the vial exploding or blowing off its cap with dangerous force creating flying debris. Unless necessary, ATCC recommends that these cultures be stored in the vapor phase of liquid nitrogen rather than submersed in liquid nitrogen.

Detailed product information

Handling information

Handling procedure
Storage and Culture Initiation

Frozen ampules packed in dry ice should either be thawed immediately or stored in liquid nitrogen.  If liquid nitrogen storage facilities are not available, frozen ampoules may be stored at or below -70°C for approximately one week.  Do not under any circumstance store frozen ampules at refrigerator freezer temperatures (generally -20°C).  Storage of frozen material at this temperature will result in the death of the culture.

  1. To thaw a frozen ampule, place it in a 35°C water bath such that the lip of the ampule remains above the water line. Thawing time is approximately 2 to 3 minutes.  Do not agitate the ampule.  Do not leave ampule in water bath after it is thawed.  Do not allow ampule to overheat.
  2. Add the thawed contents to a petri plate or T-25 tissue culture flask optionally containing a bed of non-nutrient agar (ATCC medium 919) and 10 mL ATCC medium 2454.
  3. Aseptically transfer an appropriate volume of washed Chlorogonium to the petri plate or T-25 flask (see section on MAINTENANCE OF CULTURE below).  Incubate the culture at 20-25°C
Handling notes

This strain must be fed with live Chlorogonium elongatum (i.e., ATCC® 50936™ or similar, not provided).  The Chlorogonium should be maintained separately and fed to Actinophrys at regular intervals.

This culture is monoxenic, free from bacterial flora.

Culture maintenance

Periodically add prey organisms as follows:

  1. Maintain growing cultures of Chlorogonium separately at 25°C in T-25 tissue culture flasks containing 10 mL appropriate fresh medium.
  2. Prepare washed Chlorogonium as follows:  Remove 5-10 mL from a culture at or near peak density, centrifuge at 500-600 x g for 5 min, quickly remove most of the supernatant (leaving approx. 1 mL), then resuspend cells in 10 mL ATCC medium 2454.  Centrifuge and resuspend cells again as above.  This washing step should be performed at least twice.
  3. Add an appropriate volume of washed Chlorogonium prepared in step 2 when the number of Actinophrys begins to decline and/or significant cyst formation occurs.  Add approximately 100-150 prey organisms per heliozoan for the initial inoculation of prey into a new Actinophrys culture.  Attempt thereafter to maintain a Chlorogonium cell density of approximately 2-3 x 104/mL for optimal growth of Actinophrys.  The feeding interval will depend on the number of heliozoans present and the culture density of the washed prey.
  4. The Actinophrys may be passaged to a new petri plate or T-25 flask by gently rubbing the agar or plastic surface with a spread bar to dislodge attached heliozoans, then transferring 0.5 to 2 mL to a fresh petri plate or T-25 flask optionally containing a bed of non-nutrient agar (ATCC medium 919) and 10 mL ATCC medium 2454.  Incubate the culture at 20-25°C, feeding periodically with washed Chlorogonium.
Reagents for cryopreservation
Cryoprotective Solution
DMSO 1.0 mL
Betaine 1.0 mL
Fresh growth medium 8.0 mL
  1. Mix the components in the order listed. When the medium is added to the DMSO the solution will warm up due to chemical heat.
  2. Harvest Actinophrys cells from a culture that has recently passed peak density by centrifugation at 300-400 x g for 5 min.
  3. Adjust the concentration of cells to 1-2 x 104/mL in fresh medium.
  4. Mix the cell preparation and the cryoprotective solution in equal portions by adding the cryoprotective solution to the cell suspension in 2 equal aliquots approximately 1 min apart.
  5. Dispense in 0.5 mL aliquots into 1.0 - 2.0 mL sterile plastic screw-capped cryules (special plastic vials for cryopreservation).
  6. Place vials in a controlled rate freezing unit. From room temperature cool at -1°C/min to -40°C. If freezing unit can compensate for the heat of fusion, maintain rate at -1°C/min through heat of fusion. At -40°C plunge ampules into liquid nitrogen. Alternatively, place the vials in a Nalgene 1°C freezing apparatus.  Place the apparatus at -80°C for 1.5 to 2 hours and then plunge ampules into liquid nitrogen.  (The cooling rate in this apparatus is approximately -1°C/min.)  
  7. Ampules are stored in either the vapor or liquid phase of a nitrogen refrigerator.
  8. To establish a culture from the frozen state place the vial in a 35°C water bath. Immerse the vial to a level just above the surface of the frozen material. Do not agitate the vial. Immediately after thawing, do not leave in water bath, aseptically remove the contents of the ampule and transfer to a petri plate or T-25 tissue culture flask optionally containing a bed of non-nutrient agar (ATCC medium 919) and 10 mL ATCC medium 2454
  9. Aseptically transfer an appropriate volume of washed Chlorogonium to the petri plate or T-25 flask (see section on MAINTENANCE OF CULTURE).  Incubate the culture at 20-25°C. Once the culture is established, follow the protocol for maintenance of culture.


Deposited as
Actinophrys sol Ehrenberg
T Suzaki
Type of isolate
Year of origin
Special collection
NSF - Protistology

Legal disclaimers

Intended use
This product is intended for laboratory research use only. It is not intended for any animal or human therapeutic use, any human or animal consumption, or any diagnostic use.

The product is provided 'AS IS' and the viability of ATCC® products is warranted for 30 days from the date of shipment, provided that the customer has stored and handled the product according to the information included on the product information sheet, website, and Certificate of Analysis. For living cultures, ATCC lists the media formulation and reagents that have been found to be effective for the product. While other unspecified media and reagents may also produce satisfactory results, a change in the ATCC and/or depositor-recommended protocols may affect the recovery, growth, and/or function of the product. If an alternative medium formulation or reagent is used, the ATCC warranty for viability is no longer valid.  Except as expressly set forth herein, no other warranties of any kind are provided, express or implied, including, but not limited to, any implied warranties of merchantability, fitness for a particular purpose, manufacture according to cGMP standards, typicality, safety, accuracy, and/or noninfringement.


This product is intended for laboratory research use only. It is not intended for any animal or human therapeutic use, any human or animal consumption, or any diagnostic use. Any proposed commercial use is prohibited without a license from ATCC.

While ATCC uses reasonable efforts to include accurate and up-to-date information on this product sheet, ATCC makes no warranties or representations as to its accuracy. Citations from scientific literature and patents are provided for informational purposes only. ATCC does not warrant that such information has been confirmed to be accurate or complete and the customer bears the sole responsibility of confirming the accuracy and completeness of any such information.

This product is sent on the condition that the customer is responsible for and assumes all risk and responsibility in connection with the receipt, handling, storage, disposal, and use of the ATCC product including without limitation taking all appropriate safety and handling precautions to minimize health or environmental risk. As a condition of receiving the material, the customer agrees that any activity undertaken with the ATCC product and any progeny or modifications will be conducted in compliance with all applicable laws, regulations, and guidelines. This product is provided 'AS IS' with no representations or warranties whatsoever except as expressly set forth herein and in no event shall ATCC, its parents, subsidiaries, directors, officers, agents, employees, assigns, successors, and affiliates be liable for indirect, special, incidental, or consequential damages of any kind in connection with or arising out of the customer's use of the product. While reasonable effort is made to ensure authenticity and reliability of materials on deposit, ATCC is not liable for damages arising from the misidentification or misrepresentation of such materials.

Please see the material transfer agreement (MTA) for further details regarding the use of this product. The MTA is available at

Permits & Restrictions

Import Permit for the State of Hawaii

If shipping to the U.S. state of Hawaii, you must provide either an import permit or documentation stating that an import permit is not required. We cannot ship this item until we receive this documentation. Contact the Hawaii Department of Agriculture (HDOA), Plant Industry Division, Plant Quarantine Branch to determine if an import permit is required.


Frequently Asked Questions


Curated Citations

Kinoshita E, et al. The ultrastructure of contractile tubules in the heliozoon Actinophrys sol and their possible involvement in rapid axopodial contraction. J. Eukaryot. Microbiol. 48: 519-526, 2001. PubMed: 11596916

Sakaguchi M, Suzaki T. Monoxenic culture of the heliozoon Actinophrys sol. Eur. J. Protistol. 35: 411-415, 1999.

diluted to 10% with sterile distilled water

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