What this work is about, in plain words
The rare diatom Halamphora kolbei has been described again in detail from a Black Sea culture: its external structure, place on the family tree, growth and biomass composition. According to the authors, almost 38 % of its fatty acids is the omega-3 eicosapentaenoic acid.
Halamphora kolbei is a small bottom-dwelling diatom that is rarely found and hard to identify: the original description of the species is imprecise, and information about it is scattered. The authors set two tasks: to give a reliable description by which other researchers can recognize the species, and to assess whether it is useful for biotechnology.
Cells were isolated from fouling on stones in Sevastopol Bay and grown into a pure culture. It was studied under light and scanning electron microscopes, and the species' place among its relatives was determined from two genes. The culture was then grown in a laboratory photobioreactor on an enriched nutrient medium, and growth and biomass composition were measured at different stages.
According to the authors, culture density reached 1.44 g dry weight per liter on day 10, with the highest productivity of 0.2 g/(L·day) in the first six days. The biomass contained up to 40 % protein, and lipids rose from 12 % in the growth phase to 22 % in the stationary phase. Eicosapentaenoic acid (omega-3) was the most abundant fatty acid at 37.8 %, with polyunsaturated acids totalling 56 %. The cells settle quickly, which makes harvesting the biomass easier.
The work refines the description of the species and presents it as a possible source of omega-3 acids, for example for aquaculture feed.
Limitations. A laboratory experiment with one growth cycle. The authors describe use in feed, supplements and medicines as possible, but did not test it.