How can I save bacillus strains on filter paper without an -80 degree freezer?
Use agar stubs: pour some Nutrient agar (or any suitable agar medium) in a test tube (~10% of the tube volume) and punch your inoculum halfway into it using a pipette tip or inoculation loop. Store it in 4⁰C.

Glycerol stocks can be made and stored in -20⁰C also.