Could B.Subtilis ssp. mesentericus develop in proofing stage?
My last breads suffer from B.Subtilis ssp. mesentericus infection - the bread became sticky in hours and apparently ill.


Bacillus mesentericus is a spore forming bacteria, known for causing rope/ropey like bread.  It's a soil/grass based bacteria so may have been in the flour.


  I threw away all the disposable utensils and washed the whole kitchen with vinegar and detergents. I am aware that these means are insufficient, but I had not other options


You may have been a bit hasty, the information in the link below suggests cleaning everything with vinegar for 3 consecutive days.

More information here including on diagnosis &amp; treatment (under 3.5.3)

If you would like to know more, you can have a search there's a wealth of information especially academic articles.