What additional step is required when culturing anaerobic bacteria?

The correct answer indicates the necessity of utilizing oxygen-free environments for culturing anaerobic bacteria. Anaerobic bacteria are those that either cannot survive in the presence of oxygen or their growth is inhibited by oxygen. Culturing these organisms requires specific conditions that eliminate oxygen to ensure their viability and proliferation.

This is typically achieved through methods such as using anaerobic chambers, sealed vials, or specialized growth media that promote anaerobic conditions. These environments often incorporate gases like nitrogen, hydrogen, or carbon dioxide to create an oxygen-free atmosphere, which is essential for the metabolic processes of anaerobic bacteria.

In contrast, options that suggest exposure to oxygen or light are fundamentally at odds with the growth requirements of anaerobic organisms, as oxygen and light can be detrimental to their survival. Therefore, creating an oxygen-free environment is a critical step in successfully culturing anaerobic bacteria.