In capnophilic incubators, which CO2 concentration range is typically maintained?

• A. 15%-20%
• B. 5%-10%
• C. 1%-5%
• D. 10%-15%

Answer: (B)

Capnophilic incubators are designed to provide a CO2-rich atmosphere because certain bacteria grow best when CO2 levels are elevated. The typical CO2 concentration kept is five to ten percent. This amount helps maintain the medium’s pH through the bicarbonate buffering system and matches the growth requirements of capnophilic organisms like Neisseria and Haemophilus species. Too little CO2 would not support their growth well, while too much CO2 can push the system beyond what the media can buffer and may unnecessarily stress the culture. Five to ten percent strikes the standard balance used in routine labs for these organisms.