Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Biodiesel-derived glycerol is a promising substrate for mixotrophic cultivation of oleaginous microalgae, which can also reduce the cost of microalgal biodiesel. The objective of this study is to investigate the potential of using glycerol and glucose as a complex carbon substrate to produce microalgal biomass and biochemical components, such as photosynthetic pigments, lipids, soluble carbohydrates and proteins by Chlorella vulgaris. The results show that C. vulgaris can utilize glycerol as a sole carbon substrate, but its effect is inferior to that of the mixture of glycerol and glucose. The effect of glycerol and glucose could enhance the algal cell growth rate, biomass content and volumetric productivity, and overcome the lower biomass production on glycerol as the sole organic carbon source in mixotrophic culture medium. The utilization of complex organic carbon substrate can stimulate the biosynthesis of lipids and soluble carbohydrates as the raw materials for biodiesel and bioethanol production, and reduce the anabolism of photosynthetic pigments and proteins. This study provides a promising niche for reducing the overall cost of biodiesel and bioethanol production from microalgae as it investigates the by-products of algal biodiesel production and algal cell hydrolysis as possible raw materials (lipids and carbohydrates) and organic carbon substrates (soluble carbohydrates and glycerol) for mixotrophic cultivation of microalgae.Glicerol dobiven iz biodizela može se upotrijebiti za uzgoj miksotrofnih mikroalgi iz kojih se proizvodi ulje, te za smanjenje troškova proizvodnje biodizela. Svrha je ovoga rada bila ispitati mogućnost primjene glicerola i glukoze u složenoj hranjivoj podlozi za uzgoj alge Chlorella vulgaris, te proizvodnju biomase i biokemijskih sastojaka, kao što su fotosintetski pigmenti, lipidi, topljivi ugljikohidrati i proteini. Rezultati potvrđuju da se alga Chlorella vulgaris može uzgojiti na glicerolu kao jedinom izvoru ugljika, iako su bolji rezultati postignuti uzgojem na podlozi s glicerolom i glukozom. Stopa rasta, prinos biomase i volumetrijska produktivnost alge povećani su primjenom podloge s glicerolom i glukozom, u usporedbi s podlogom koja sadržava samo glukozu kao organski izvor ugljika. Uporabom složene hranjive podloge može se ubrzati biosinteza lipida i topljivih ugljikohidrata (sirovina za proizvodnju biodizela i bioetanola), te usporiti sinteza fotosintetskih pigmenata i proteina. U radu je ispitana mogućnost primjene nusproizvoda dobivenih proizvodnjom biodizela i hidrolizom algi te podloga s organskim izvorima ugljika (topljivi ugljikohidrati i glicerol) kao sirovina (izvor lipida i ugljikohidrata) za proizvodnju miksotrofnih mikroalgi, radi smanjenja ukupnih troškova proizvodnje biodizela i bioetanola
