Culturing information

Culture conditions

All cultures in the CPCC are grown in defined media (see culture media). Cultures are grown in controlled environment chambers primarily at 20°C; a small number of strains are kept at 10°C or at 23°C. All are grown under low lighting (~15-30 uE/m2/s) using fluorescent Cool-White or Daylight lamps and a Day:Night cycle of 12:12. All cultures are currently maintained by serial transfer. Duplicate cultures are kept in a back-up environmental chamber for each of the three temperatures in use.

Several cultures in flasks

Please note that these conditions are designed to keep the cultures healthy while maintaining them at a slow growth rate. While this may be in direct opposition to the goals of the majority of our users who might wish to grow their cultures at a much faster rate, this is the only way the CPCC can keep the cultures viable with limited staffing and resources. When you first receive your new cultures, it is recommended that they be kept under similar environmental conditions as at the CPCC until the culture are well-established at your own facility.

Some of the valuable isolates have been cryopreserved in liquid nitrogen for long-term storage to further ensure their long-term maintenance and genetic stability.

More detailed culturing information, including the environmental conditions and type of culture medium used for each specific isolate is available by email from the technical curator. Persons purchasing a particular strain for the first time are strongly encouraged to receive this information prior to receiving the cultures

Culture acclimation

Upon first receiving your cultures, please bear in mind that they have undergone some shipping stress and will now need to acclimate to their new environment at your facility. Motile organisms in particular seem to be very vulnerable to shipping stress. After unpacking your cultures, place the unopened tubes into your growth area overnight to begin their adjustment to the new environmental conditions. Although your ultimate goal may be to produce higher growth rates, it would be best to attempt to reproduce our culturing conditions as closely as possible until the cultures are firmly established in their new home. Please contact the technical curator for details on the environmental conditions used for the strain you are purchasing.

Except for certain "weedy" genera such as Chlorella spp. and Pseudokirchneriella subcapitata, great care must be taken to avoid loss of your new cultures. When you prepare the new subcultures from the shipping tubes, please examine the cultures microscopically to determine viability. A good rule of thumb is to use 2/3 of the liquid culture to prepare duplicate cultures while leaving the remaining 1/3 of the culture in the tube as a backup in case the first set of subcultures doesn't grow well. Also, use a low dilution rate of approximately 1 part culture to 5 parts medium. For example, from a 15 mL liquid culture, prepare two new subcultures by diluting ~5 mL of the donor culture with ~20-25 mL of fresh medium. It is recommended that the duplicate vessels be placed in two different locations with similar environmental conditions in the event that one replicate grows while the other does not. Once these cultures are growing well, they may be scaled up further by adding ~10 mL of the donor culture to ~50 mL of medium with multiple replicates. Once these cultures are well-established in your facility, you may proceed with further scaling up of either volume and/or replicates, and modifications may be made to the environmental conditions (e.g., lighting, temperature, photoperiod) in order to speed up the growth of the cultures. Depending upon the strain, the amount of stress suffered during shipment, and the degree of difference in environmental conditions, culture acclimation may take from several weeks to several months.

Culturing & aseptic technique

Newcomers to the field of algal culturing and aseptic technique may find it useful to read Chapters 2 (Freshwater Culture Media), 3 (Marine Culture Media) 5 (Sterilization and Sterile Technique), and Appendix A (Recipes for Freshwater and Seawater Medium) of Robert A. Andersen's "Algal Culturing Techniques" book (2005). This book may be purchased from Amazon. You may also be able to access this book online (as a PDF) from ResearchGate as of March 14, 2023.

Customized training workshops for algal culturing, maintenance, medium preparation, and aseptic technique are also available here at the CPCC.