I have a supplement for use in horticulture. It is a powder that contains mostly subtilis with smaller amounts of a few other strains.

Prior to horticultural application I would like to "multiply" them so as to get to most out of the product.

Is water and a drop of molasses sufficient? (that seems to be accepted in cannabis culture)

How fast do these guys replicate? Without high tech lab equipment is there anyway I can tell that they are in fact multiplying?

  • $\begingroup$ You need to add some protein to your media. Use yeast extract if it is available or just boiled commercial baking yeast. $\endgroup$ Commented Mar 8, 2016 at 15:25

1 Answer 1


I am basing my answer on this document issued by one of the departments of the Ludwig Maximilian University of Munich.

Bacillus subtilis:

  • Doubling time: 30 minutes
  • Incubation temperature: 37°C
  • Growth conditions: strictly aerobe

Recommended media:

  • Luria-Bertani (LB) broth/plates - (for everyday use)
  • Difco Sporulation Medium (DSM) - (for long-term storage)

You can find the formulations for the aforementioned media by following the link above.

With regards to the latter part of your question, the easiest way to tell (and doesn't require any "high-tech" lab equipment) whether your cells are multiplying or not is to inoculate a broth and see whether there is turbidity after a certain time of incubation. However, please be aware that you may have cross-contaminated your broth so unless you do further testing you cannot know for certain if it is Bacillus subtilis in your broth.


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