Harvesting of microalgae Picochlorum sp. by bioflocculation with fungus Mortierella isabellina

Bioflokulacija predstavlja inovativnu, ekonomičnu i ekološki prihvatljivu metodu izdvajanja biomase mikroalge. U ovome radu provedeni su eksperimenati sa ciljem optimizacije uvjeta bioflokulacije mikroalge Picochlorum sp. s peletima plijesni Mortierella isabellina. Optimizirana je koncentracija spora plijesni te utjecaj mase plijesni, pH vrijednosti, temperature i omjera masa plijesni i mikroalge. Maksimalna uspješnost bioflokulacije iznosila je 88,47 %, postignuta pri uvjetima: 1,5 g suhe tvari plijesni u omjeru mikroalga:plijesan 1:50, pri pH vrijednosti 2 i temperaturi 30 °C. Također proveden je fototrofni šaržni uzgoj mikroalge uz sukcesivno dodavanje nutrijenata u barbotirajućoj koloni na f/2 podlozi. Uzgoj je proveden kroz fazu uzgoja i fazu nakupljanja lipida uz dodatak natrijevog bikarbonata. Posljednjeg 26. dana uzgoja postignuta koncentracija biomase iznosila je 1,68 g/L. Tijekom uzgoja praćene su promjene udjela proteina, ugljikohidrata i lipida, sastav pigmenata te profil masnih kiselina. Najzastupljenije makromolekule u biomasi bili su proteini (76,09 %), a zatim ugljikohidrati (37,69 %) i lipidi (14,18 %).Bioflocculation is an innovative, economically and environmentally friendly method of extracting microalgae biomass. In this paper, experiments were performed with the aim of optimizing the bioflocculation conditions for the Picochlorum sp. with Mortierella isabellina pellets. Concentration of mold spores, influence of mold mass, pH value, temperature and mass ratio of mold and microalgae were optimized. The maximum efficiency of bioflocculation was 88.47 %, achieved under the following conditions: 1.5 g of mold dry matter in the ratio of microalgae: mold 1:50, at pH 2 and temperature 30 ° C. Phototrophic batch culture of microalgae was also performed with successive addition of nutrients in a bubbling column on f/2 medium. Cultivation was carried out through the culture phase and the lipid accumulation phase with the addition of sodium bicarbonate. On the last day of cultivation (26.), the achieved biomass concentration was 1.68 g/L. During cultivation, changes in the content of proteins, carbohydrates and lipids, the composition of pigments and the profile of fatty acids were monitored. The most represented macromolecules in biomass were proteins (76.09 %), followed by carbohydrates (37.69 %) and lipids (14.18 %)