What this work is about, in plain words
The authors developed a nutrient medium on which the diatom Cylindrotheca closterium produces dense cultures. The composition of the medium was calculated from how much nitrogen, phosphorus and silicon the biomass itself contains.
To obtain a dense microalgae culture, the cells need enough minerals for the whole growth cycle. Standard media are usually not designed for this. The authors set out to develop a medium for intensive cultivation of the diatom Cylindrotheca closterium.
First, chemical analysis determined how much nitrogen, phosphorus and silicon the biomass contains. From these data, the requirements of the culture and the composition of the new medium were calculated. The culture was then grown on it as a batch, and the consumption of the elements was monitored.
According to the authors, productivity reached 1 g of dry weight per liter per day in the first three days and then declined. Maximum density was 4.6 g of dry biomass per liter. When nitrogen ran short, the cells began to stick together, while high iron concentrations did not inhibit growth. On average, about 10 % of the nitrogen was lost: part of it remained in the medium as organic substances released by the cells themselves.
The new medium makes it possible to obtain dense cultures from which valuable substances can then be extracted, above all the pigment fucoxanthin and polyunsaturated fatty acids.
Limitations. The work was done on a laboratory culture grown as a batch. The behavior of the medium in continuous-flow mode and in large volumes was not studied in the article.