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Care Guide: Rhodospirillum rubrum

Living Care Information

Rhodospirillum rubrum
commonly known as Rhodospirillum

Quick Start Information

  • When your order arrives, open the shipping box immediately and remove the culture. Visually inspect the culture to ensure that tubes are intact with caps securely in place and plates are free of cracks and taped along the edges.

  • Leave the culture sealed—do not loosen the lid or remove tape around plate—and keep it at room temperature (20 to 25° C). Ambient room light is sufficient if you plan to use the culture within 3 weeks.

  • If you plan to set up subcultures from your culture, you should keep it about 40 cm (16") below a constant fluorescent light.

About the Organism

  • Rhodospirillum rubrum is a photosynthetic bacterium and possesses special organelles called bacteriochlorophylls that absorb light between 800 and 925 nanometers.
  • Rhodospirillum rubrum grows anaerobically when light is available and aerobically in the dark.
  • The organism was originally isolated from mud and stagnant water.
  • Rhodospirillum rubrum can be red to pink in color.
  • Individual spiral cells measure between 800 and 1000 nanometers.
  • Domain: Eubacteria
  • Kingdom: Bacteria
  • Phylum: Proteobacteria
  • Class: Alphaproteobacteria
  • Order: Rhodospirillales
  • Family: Rhodospirillaceae
  • Genus: Rhodospirillum
  • Species: rubrum


We ship R. rubrum in tubes, either on solid slant media, in broth, or as a plate culture.

Cultures remain viable for 2 to 3 weeks before they will need to be subcultured. Plan to set up new cultures at least every 3 weeks.

R. rubrum grows more slowly than many bacteria species, so it may take 5 to 7 days for visible growth to appear on newly inoculated media.


No Housing information needed for this organism.


No Feeding information needed for this organism.

Maintaining and culturing

Culture R. rubrum using tryptic soy agar, nutrient agar, or nutrient broth. Transfer broth cultures to fresh broth with a sterile pipet or loop, or streak colonies onto agar using a sterile inoculating loop. See the instruction manual Techniques for Studying Bacteria and Fungi for more information on setting up bacterial cultures. Because of its slow growth, we recommend inoculating R. rubrum slightly more heavily than you might with other bacteria.

After you inoculate the new tube or plate, seal it by screwing on the cap or taping the edges of the plate. Place the new cultures about 40 cm (16") below a fluorescent light, and keep the light on 24 hours a day. Incubate the cultures at 25° C.


When you have finished setting up the cultures, clean the work area with disinfectant and wash your hands again.

To dispose of cultures that are no longer needed, autoclave the cultures at 121°C for 20 minutes or submerge them in a disinfectant such as 70% alcohol or a 10% bleach solution overnight. You can then discard the cultures with regular solid waste.


Rhodospirillum rubrum is classified as a Biosafety Level 1 organism. Before you work with bacterial cultures, wash your hands with soap and water, ensure that the work area is draft free, and wipe down the work surface with 70% alcohol or a similar disinfectant. Never work in an area where food is prepared or consumed


No suggested Video or Video Playlist available for this organism.


What happens if I grow Rhodospirillum rubrum in the dark?

Without light, the organism will appear colorless rather than pink or red. R. rubrum grows aerobically when it cannot photosynthesize. To grow it in the dark, loosen the culture lids or untape the plates to allow gas exchange.

How many subcultures can I set up from 1 tube or plate?

One broth culture can be used to inoculate about 25 new broth cultures or plates. One plate can be used to inoculate 10 plates or about 40 slant tubes. One slant tube can inoculate about 10 new slant tubes.

Why do I see some bacteria with less of a spiral shape?

Under less favorable culture conditions, such as when a culture has been kept for a long time without subculturing, some of the cells may develop abnormal shapes or sizes.

Where does the organism occur in the wild?

Outside of the lab, R. rubrum grows in stagnant water and mud exposed to light.

Need help?

We want you to have a good experience. Orders and replacements: 800.334.5551, then select Customer Service. Technical support and questions: caresheets@carolina.com