What this work is about, in plain words
When should a diatom crop be harvested to contain the most valuable substances? The authors traced how the composition of Cylindrotheca closterium biomass changes as the culture grows.
The composition of microalgae biomass depends on the growth stage at which it is harvested. For production, it is important to know when the cells contain the most of the substances needed. The authors traced how the biochemical composition of the diatom Cylindrotheca closterium changes over the whole cultivation cycle of one batch.
The culture was grown as a batch, and the content of lipids, fatty acids, carbohydrates, proteins and the pigment fucoxanthin was measured at different stages.
According to the authors, during fast growth the biomass contains few lipids (about 3 % of dry weight) and many carbohydrates (about 23 %). When growth stops, the picture reverses: lipids rise to 28 % and carbohydrates fall to about 7 %. Fucoxanthin behaves similarly: from 0.5–1 mg per gram of dry weight during growth to 20 mg per gram at the end of the cycle, on day 21. Omega-3 acids predominate among the fatty acids.
The practical conclusion: if lipids and fucoxanthin are needed, it is better to harvest the biomass at the end of the cycle, after growth stops.
Limitations. The work describes one batch cultivation scheme. Under a different regime, for example continuous flow, the composition may differ. The results were obtained by the authors of the article and do not describe Laboratory 17 batches.