Stability of Bacillus Spores

  • MDG

Bacillus species are known for their ability to form spores, which allows them to remain stable under adverse environmental conditions. Sporulation is a naturally occurring phenomenon that serves to protect Bacillus species when conditions for growth are unfavorable. During sporulation, Bacillus form a protective spore coat and enter a dormant state where they remain viable but metabolically inactive. The spore coat also serves to protect against harsh environmental conditions, like extreme heat, pH levels, pressure, chemical interactions, desiccation and more. When moisture and nutrients are available, Bacillus spores will germinate and begin to grow. Germination can happen in a matter of minutes or hours depending on the strain and environmental conditions, even after years in a dormant state. This unique attribute gives Bacillus products long-term shelf life stability.


Figure 1. Total Bacillus count (CFU/g) in a powdered Bacillus spores stored at the recommended storage conditions for three years.

A powdered blend of Bacillus spores at four billion CFU/g were stored under recommended storage conditions for three years. Bacillus was enumerated at 18 months and 36 months (Figure 1).

Over the three-year period, the Bacillus count remained consistent within the typical margin of error.


SporActiv™ products contain sporulated Bacillus strains that will remain stable and viable for years. This gives SporActiv™ products a long shelf life and ensures that efficacy remains consistent even after years in storage.


At the end of each fermentation batch, MDG submits the batch to pasteurization temperatures and processes. This process kills off vegetative cells, leaving only shelf-stable spores remaining!


* Recommended storage conditions: The shelf life of MDG products is two years when stored dry at temperatures of 36-77°F/5-25°C.