Accumulation of proteins in the medium of the various naturally occurring Chlorella and Scenedesmus microalgae containing and not-containing algaenan

Depending on a specific strain, the chlorococcalean microalgae cell walls contain or lack a biopolymer called algaenan, highly resistant to chemical and enzymatic treatment. This study aimed to investigate whether the presence or absence of algaenan affects the ability of the selected strains to accumulate proteins in the growth medium. The study was conducted on 20 green microalgae strains, including 11 strains without algaenan and 9 strains with algaenan in their cell walls. The concentration of the proteins in the medium was estimated after 30 days of algae growth using the tannin micromethod. It was demonstrated that algaenan-lacking microalgae accumulated significantly more proteins in the medium than strains containing this biopolymer. Thus, it can be concluded that the cell wall structure resulting from algaenan presence is responsible for the differences in protein accumulation in the medium. These proteins, which are part of the soluble extracellular polymeric substances, can be beneficial for obtaining active substances or can be a factor hindering the application of algae for industrial purposes due to film or foam formation. Thus, the results obtained in this study may give valuable clues for strain selection regarding specific application.