Browsing by Subject "TRIACYLGLYCEROLS"

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  • Tossavainen, Marika; Katyal, Neha; Silja, Kostia; Valkonen, Kalle; Sharma, Anil K.; Sharma, Suvigya; Ojala, Anne; Romantschuk, Martin (2018)
    Microalgae are a sustainable alternative for production of valuable omega -3 fatty acids (FAs), but high production costs limit commercialization. Utilization of waste as a nutrient source increases the economics of the cultivation process. Additionally, using mixed algal cultures instead of monocultures makes the cultivation process more flexible and can increase biomass and lipid production. Here, the growth and lipid production of microalgae Euglena gracilis, Selenastrum sp. and, Chlorella sorokiniana were studied in mono- and mixed cultures in small and pilot scale experiments in biowaste leachate. In pilot scale, also nutrient reduction and the number of bacteria were analyzed. Biomass production in the most productive mixed cultures was similar, but not higher than in most productive monocultures. The lipid production was highest in the small-scale monoculture of Selenastrum (10.4% DW) and in the pilot scale culture of Selenastrum with E. gracilis (11.1% DW). The content of alpha-linolenic acid (ALA) increased and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) remained stable during the cultivation period in all pilot scale cultures. However, increases in biomass and lipid production toward the end of the cultivation resulted in higher EPA and DHA yields in the well growing monoculture of E. gracilis and in the mixed culture of E. gracilis with Selenastrum. Co-cultivation of E. gracilis and Selenastrum also had a positive influence on nutrient uptake and resistance against bacteria. This type of mixed culture may be a good option for commercialization. However, as shown here, minor changes in cultivation conditions can rapidly result in dominance of a subdominant strain, and thus the stability of strain performance and production of desired FAs needs further investigation.
  • Lynch, Fiona; Santana-Sanchez, Anita; Jämsä, Mikael; Sivonen, Anna Kaarina; Aro, Eva-Mari; Allahverdiyeva, Yagut (2015)
    The value and efficiency of microalgal biofuel production can be improved in an integrated system using waste streams as feed-stock, with fuel-rich biomass and treated wastewater being key end-products. We have evaluated seven native cyanobacterial isolates and one native green alga for their nutrient removal, biomass accumulation and lipid production capacities. All native isolates were successfully grown on synthetic wastewater mimicking secondary treated municipal wastewater (without organic carbon). Complete phosphate removal was achieved by the native green alga, isolated from Tvarminne (SW Finland). Optimisation of the C:N ratio available to this strain was achieved by addition of 3% CO2 and resulted in complete ammonium removal in synthetic wastewater. The native green alga demonstrated similar nutrient removal rates and even stronger growth in screened municipal wastewater, which had double the ammonium concentration of the synthetic media and also contained organic carbon. Sequencing of the genes coding for 18S small rRNA subunit and the ITS1 spacer region of this alga placed it in the Scenedesmaceae family. The lipid content of native isolates was evaluated using BODIPY (505/515) staining combined with high-throughput flow cytometry, where the native green alga demonstrated significantly greater neutral lipid accumulation than the cyanobacteria under the conditions studied. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).