Spore suspensions are calibrated suspensions of bacterial spores appropriate for direct inoculation of products or preparing custom biological indicators for monitoring Steam, Ethylene Oxide (EtO), Dry Heat, Hydrogen Peroxide, Radiation and other industrial sterilization processes.

Each vial contains 10 ml of suspension. The suspending liquid is 20%, 29%, or 40% ethanol or purified water.


Mesa manufactures many species of non-pathogenic spore-forming bacteria. Most are used for various types of sterilization, though some have other uses. Following is a brief description of the most common uses:

  • G. stearothermophilus* (reference # 7953) for steam.
  • B. atrophaeus* (reference # 9372) for dry heat and EO
  • B. pumilus* (reference # 27142) for gamma irradiation
  • B. subtilis* “5230” (reference #35021) – used for low temperature steam applications of heat sensitive products that may be compromised by the time and temperature of the standard 121°C steam sterilization cycle.
  • B. subtilis* (reference # 6633) – Used to test the growth promotion ability of bacteriological media (specified in USP and other compendial monographs). We do not certify this organism with any resistance characteristics.
  • G. stearothermophilus* (reference # 12980) is widely used in the validation of Hydrogen Peroxide (H2O2) vapor sterilization of barrier isolators and clean areas in pharmaceutical production. This species is typically inoculated onto steel carriers so it is compatible with the H2O2 process and similar in material to items typically found in these production areas. This organism is certified with an H2O2 D-value.
  • B. smithii (reference #51232) is used in steam sterilization of liquid products.  This organism is certified with a 121°C steam D-value determined on spores suspended in water for injection (WFi), in glass ampoules.
  • Clostridium sporogenes (reference 11437, 19404 or 7955) is used for low temperature steam or pasteurization applications in the food industry.  Clostridium sporogenes is used as a surrogate for pathogens such as Clostridium botulinum and Clostridium perfringens.

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