A microbiologist is culturing Bacillus subtilis to investigate its resistance to a newly synthesized antibiotic. During the inoculation of the nutrient agar plate, they perform the following two actions:

• Step A: Flame the neck of the glass bottle containing the bacterial culture both immediately after opening and before sealing it.
• Step B: Lift the lid of the Petri dish at an angle, only opening it as far as necessary to introduce the inoculating loop.

State the primary purpose of carrying out both Step A and Step B.