The best thing to do is keep them away. If you succeed, any additional measures will all be effective or not needed. However, if some spore forming spoilage bacteria slip thru, there are two ways to deal with them. First is by pressure heating, 121 C for 15 minutes or thru the use of old school tyndallization method.
After reviewing the properties of spore forming bacteria, recalling how heat resistant and resilient it is and knowing that it activates and become vulnerable when condition is favorable. I thought the culprit could be attacked and successfully eliminated by allowing it to activate then heat it while on its most vulnerable state. A dirty war tactic.
If feasible, it might allow sterilization in absense of autoclave and pressure cooker and could be done on heat sensitive items such as plant seeds.
Just as I thought, it is feasible. It is an old and long process known as tyndallization. The food in process is boiled for few minutes, about 15 to 40 minutes depending on food type and volume. The process is repeated after 24 hours and after 72 hours. The food temperature is maintained at 37 C between boiling period. That is to allow spore activation and prevent its formation.