The Spiritus Mundi/Secret Fire topic is still going on, and it's very good.
Lastly a logical idea came to the surface of the little Alchemical world : How could putrefaction occurs if one just sterilize the matter ? Were the SM in the bacterias in this case ? Is Spiritus Mundi a big trap then ?
Well, there is a concept I must stress on : Vulgar vs Philosophical.
This world is closed to the chemists' vision. Impossible for him to be deciphered.
It's only for the Hermeticians.
Everything can be seen under these two points of view. Vulgar or Particular, and Philosophical or Universal.
And thus, for Putrefaction also !
There is a big difference between vulgar putrefaction and philosophical putrefaction.
We all know the vulgar putrefaction. Some tricks can putrefy metals or rocks, but this is still a kind of exotic vulgar putrefaction.
The Philosophical Putrefaction is very special. It can be witnessed only by Alchemists since they are in touch with the Secret Fire or Spiritus Mundi.
Spiritus can open, penetrate and putrefy everything. Sterile or not.
It will not act in a chemical way, but directly manipulate the Principles in the matter (Sulfur, Mercury and Salt). So the release of gases one can witness, etc is of course different.
There is only an analogy between the two process, but no correlation.
So no, it's not SM that causes normal putrefaction. SM is not at all enough present in order to act in such a way. The ratio is maybe of 0.000000001%, a phi putrefaction asks far far more Spiritus (and I can't say a %age unfortunately) !
So when the old Masters described a putrefaction they sometime didn't say that it was a Phi. one or a Vulg. one ! Exactly like the Fire used and the degrees of temperature.
This is why there is a lot of confusion now ...