The growth of all bacteria in a laboratory requires specific environmental conditions, including the nutrients in the media, the temperature, and the atmosphere. Much of the media that we use today was created decades ago to provide the needed nutrients to bacteria of interest.
Temperatures for bacterial growth cultures are generally set by the temperature of the natural environment in which the bacteria are found; for this reason, most pathogenic bacteria are grown at human body temperature, 37°C.
Lastly, bacteria need to have the right atmospheric environment to be able to grow in a lab; this also often mimics the conditions where the bacteria is found in nature. Some bacteria grow fine in the lab in a normal atmosphere. Some bacteria require there to be no oxygen, an anaerobic atmospheric environment like would be found in the human gut. Other bacteria need something different, such as the bacteria that cause gonorrhoea, Neisseria gonorrhoeae; these need enhanced levels of CO2 to be able to grow in the lab.
Due to this requirement for CO2, special incubators are often used to grow N. gonorrhoeae that have regulators to add CO2 from gas tanks into the atmosphere within the incubator. Growth like this requires there to be a readily available supply of CO2 gas and for there to be the special incubators able to use this gas.
There are some alternatives, such as putting the agar plates with the bacteria into sealed jars with a small candle to deplete oxygen and thus raise CO2 levels in the jar. But, these jars then take up additional space in an incubator, where space can be precious.
It would be so much easier, and more readily accessible to remote and resource limited areas, to be able to grow Neisseria gonorrhoeae and bacteria like it on media that eliminates the need for CO2.
This is what we have done in our paper, ‘Improved Neisseria gonorrhoeae culture media without atmospheric CO2.’ In Applied Microbiology and Biotechnology (10.1007/s00253-025-13449-7).
During the pandemic, there were shortages in available CO2 gas cylinders. Even outside of the pandemic, CO2 cylinders run out of gas, ruining experiments and analysis of samples. In remote areas and resource limited areas, there can be issues trying to grow bacteria such as Neisseria gonorrhoeae that have non-standard atmospheric requirements.
Our modified media solves this problem. By simply adding sodium bicarbonate to the three commonly used growth media for these bacteria, we have demonstrated growth of Neisseria gonorrhoeae in normal, standard atmosphere incubators. The GC agar, Chocolate agar, and Thayer Martin agar growth media with sodium bicarbonate are as effective as growth of the bacteria in a CO2 incubator (shown below, A in CO2, B on our media) . This opens up a world of possibilities about where and when these bacteria can be grown in laboratory conditions.