What this work is about, in plain words
Can a marine diatom be grown without a CO₂ supply, on a nutrient medium with baking soda? The authors showed that it can and found the pH range in which the culture grows best.
Diatoms can take up carbon not only from carbon dioxide but also from dissolved bicarbonate. Even so, nutrient media for them are usually designed around a supply of CO₂ from air or a gas cylinder. The authors tested whether the bottom-dwelling diatom Cylindrotheca closterium can be grown on a medium with sodium bicarbonate (baking soda) without any CO₂ supply.
The culture was grown in a one-liter flask on a nutrient medium made from Black Sea water with added soda. It was stirred with a magnetic stirrer, and growth and the acidity of the medium were monitored.
According to the authors, the culture grew actively, with productivity reaching 0.6–0.7 g dry weight per liter per day. As it grew, the medium became more and more alkaline. The culture grew best at pH 8.4 to 9.4: above that, growth slowed, and at pH 9.9 the culture began to die. By the authors' estimate, the culture still obtained at least half of its carbon from the air.
For large volumes, this approach simplifies the carbon supply to the culture, and the soda also smooths out sharp swings in acidity.
Limitations. The experiment was carried out in a single one-liter laboratory flask. Scale-up was not tested in the article. The results were obtained by the authors of the article and do not describe Laboratory 17 batches.