What this work is about, in plain words
The red microalga Porphyridium is usually supplied with carbon dioxide from a gas cylinder. The authors showed that it can be grown on a nutrient medium with baking soda as the only carbon source.
Microalgae need carbon to grow. The red alga Porphyridium purpureum is usually supplied with carbon dioxide from a cylinder, which makes cultivation more complicated and expensive. The authors tested whether sodium bicarbonate — baking soda dissolved in the nutrient medium — can take over this role entirely.
The culture was grown on seawater media with soda: first in laboratory photobioreactors, then in larger volumes under natural light.
According to the authors, the medium can contain 20 g/L of soda or more. Culture density reached 3 g of dry biomass per liter, and productivity in the laboratory was up to 1.16 g per liter per day. Under natural light, the result depended on the weather: 6.33 g per square meter per day on cloudy days and 17.7 g on sunny days. Under strong light, the culture began to die off as soon as it reached its maximum. The authors link this to the rising alkalinity of the medium, which makes some nutrients unavailable.
The work shows that the supply of carbon dioxide can be replaced with a simple and cheap reagent.
Limitations. The work was published as a short article. For natural light, individual cycles in different weather are reported. The authors offer their explanation of the culture die-off as a hypothesis. The results were obtained by the authors of the article and do not describe Laboratory 17 batches.