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Lipid production in association of filamentous fungi with genetically modified cyanobacterial cells.

Miranda AF, Taha M, Wrede D, Morrison P, Ball AS, Stevenson T, Mouradov A - Biotechnol Biofuels (2015)

Bottom Line: For most of genetically modified strains the total lipid yields extracted from the fungal-cyanobacterial pellets were found to be higher than additive yields of lipids and total free fatty acids produced by fungal and Synechocystis components when grown in mono-cultures.The synergistic effect observed in fungal-Synechocystis associations was also found in bioremediation rates when animal husbandry wastewater was used an alternative source of nitrogen and phosphorus.Fungal assisted flocculation can complement and assist in large scale biofuel production from wild-type and genetically modified Synechocystis PCC 6803 strains by (1) efficient harvesting of cyanobacterial cells and (2) producing of high yields of lipids accumulated in fungal-cyanobacterial pellets.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Sciences, Royal Melbourne Institute of Technology University, Bundoora, VIC 3083 Australia.

ABSTRACT

Background: Numerous strategies have evolved recently for the generation of genetically modified or synthetic microalgae and cyanobacteria designed for production of ethanol, biodiesel and other fuels. In spite of their obvious attractiveness there are still a number of challenges that can affect their economic viability: the high costs associated with (1) harvesting, which can account for up to 50 % of the total biofuel's cost, (2) nutrients supply and (3) oil extraction. Fungal-assisted bio-flocculation of microalgae is gaining increasing attention due to its high efficiency, no need for added chemicals and low energy inputs. The implementation of renewable alternative carbon, nitrogen and phosphorus sources from agricultural wastes and wastewaters for growing algae and fungi makes this strategy economically attractive.

Results: This work demonstrates that the filamentous fungi, Aspergillus fumigatus can efficiently flocculate the unicellular cyanobacteria Synechocystis PCC 6803 and its genetically modified derivatives that have been altered to enable secretion of free fatty acids into growth media. Secreted free fatty acids are potentially used by fungal cells as a carbon source for growth and ex-novo production of lipids. For most of genetically modified strains the total lipid yields extracted from the fungal-cyanobacterial pellets were found to be higher than additive yields of lipids and total free fatty acids produced by fungal and Synechocystis components when grown in mono-cultures. The synergistic effect observed in fungal-Synechocystis associations was also found in bioremediation rates when animal husbandry wastewater was used an alternative source of nitrogen and phosphorus.

Conclusion: Fungal assisted flocculation can complement and assist in large scale biofuel production from wild-type and genetically modified Synechocystis PCC 6803 strains by (1) efficient harvesting of cyanobacterial cells and (2) producing of high yields of lipids accumulated in fungal-cyanobacterial pellets.

No MeSH data available.


Flocculation of Synechocystis PCC 6803 cells by A. fumigatus.a SD100 culture mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, time = 0; Flocculation of SD100 (b), SD216 (c) and SD232 (d) cells with A. fumigatus/TWS and A. fumigatus/GLU pellets (t = 24 h); e Flocculation of SD277 with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; vertical bars show the levels of A. fumigatus pellets in SD277 culture; f same after 24 h; g, hA. fumigatus pellets before and after mixing with SD100 cells, respectively; i SD256 grown for 5 days under reduced CO2 conditions and mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; j same after 24 h. In a–f, i–jA. fumigatus/TWS pellets were shown on left and A. fumigatus/GLU on right. Scale 5 mm
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Fig2: Flocculation of Synechocystis PCC 6803 cells by A. fumigatus.a SD100 culture mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, time = 0; Flocculation of SD100 (b), SD216 (c) and SD232 (d) cells with A. fumigatus/TWS and A. fumigatus/GLU pellets (t = 24 h); e Flocculation of SD277 with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; vertical bars show the levels of A. fumigatus pellets in SD277 culture; f same after 24 h; g, hA. fumigatus pellets before and after mixing with SD100 cells, respectively; i SD256 grown for 5 days under reduced CO2 conditions and mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; j same after 24 h. In a–f, i–jA. fumigatus/TWS pellets were shown on left and A. fumigatus/GLU on right. Scale 5 mm

Mentions: Flocculation experiments were explained in Additional file 5: Figure S4. To assess flocculation efficiency A. fumigatus/GLU and A. fumigatus/TWS pellets were mixed with wild-type and genetically modified SD cultures that had been grown to cell densities of 1.0 × 109 cells/mL. Efficiency of harvesting was measured by the reduction in optical density and the numbers of uncaptured SD cells 24 h and 48 h after of co-cultivation with fungal pellets. Half maximal flocculation efficiencies (FE50) were calculated as the minimum amount of A. fumigatus cells required to harvest 50 % of the 1.0 × 109 cells/mL cells. A. fumigatus/GLU showed up to 86 % flocculation when co-cultivated for 24 h with SD strains (Figs. 1, 2). This increased up to 97 % after 48 h co-cultivation. Mixing A. fumigatus/TWS with SD strains showed up to 68 % flocculation after 24 h followed by 80–90 % of flocculation after 48 h. A. fumigatus/NEC showed 34–56 % flocculation rates after 24 h of co-cultivation which increased to 60 % after 48 h. FE50 data for flocculation efficiencies is shown in Table 1.Fig. 1


Lipid production in association of filamentous fungi with genetically modified cyanobacterial cells.

Miranda AF, Taha M, Wrede D, Morrison P, Ball AS, Stevenson T, Mouradov A - Biotechnol Biofuels (2015)

Flocculation of Synechocystis PCC 6803 cells by A. fumigatus.a SD100 culture mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, time = 0; Flocculation of SD100 (b), SD216 (c) and SD232 (d) cells with A. fumigatus/TWS and A. fumigatus/GLU pellets (t = 24 h); e Flocculation of SD277 with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; vertical bars show the levels of A. fumigatus pellets in SD277 culture; f same after 24 h; g, hA. fumigatus pellets before and after mixing with SD100 cells, respectively; i SD256 grown for 5 days under reduced CO2 conditions and mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; j same after 24 h. In a–f, i–jA. fumigatus/TWS pellets were shown on left and A. fumigatus/GLU on right. Scale 5 mm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig2: Flocculation of Synechocystis PCC 6803 cells by A. fumigatus.a SD100 culture mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, time = 0; Flocculation of SD100 (b), SD216 (c) and SD232 (d) cells with A. fumigatus/TWS and A. fumigatus/GLU pellets (t = 24 h); e Flocculation of SD277 with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; vertical bars show the levels of A. fumigatus pellets in SD277 culture; f same after 24 h; g, hA. fumigatus pellets before and after mixing with SD100 cells, respectively; i SD256 grown for 5 days under reduced CO2 conditions and mixed with A. fumigatus/TWS and A. fumigatus/GLU pellets, t = 0; j same after 24 h. In a–f, i–jA. fumigatus/TWS pellets were shown on left and A. fumigatus/GLU on right. Scale 5 mm
Mentions: Flocculation experiments were explained in Additional file 5: Figure S4. To assess flocculation efficiency A. fumigatus/GLU and A. fumigatus/TWS pellets were mixed with wild-type and genetically modified SD cultures that had been grown to cell densities of 1.0 × 109 cells/mL. Efficiency of harvesting was measured by the reduction in optical density and the numbers of uncaptured SD cells 24 h and 48 h after of co-cultivation with fungal pellets. Half maximal flocculation efficiencies (FE50) were calculated as the minimum amount of A. fumigatus cells required to harvest 50 % of the 1.0 × 109 cells/mL cells. A. fumigatus/GLU showed up to 86 % flocculation when co-cultivated for 24 h with SD strains (Figs. 1, 2). This increased up to 97 % after 48 h co-cultivation. Mixing A. fumigatus/TWS with SD strains showed up to 68 % flocculation after 24 h followed by 80–90 % of flocculation after 48 h. A. fumigatus/NEC showed 34–56 % flocculation rates after 24 h of co-cultivation which increased to 60 % after 48 h. FE50 data for flocculation efficiencies is shown in Table 1.Fig. 1

Bottom Line: For most of genetically modified strains the total lipid yields extracted from the fungal-cyanobacterial pellets were found to be higher than additive yields of lipids and total free fatty acids produced by fungal and Synechocystis components when grown in mono-cultures.The synergistic effect observed in fungal-Synechocystis associations was also found in bioremediation rates when animal husbandry wastewater was used an alternative source of nitrogen and phosphorus.Fungal assisted flocculation can complement and assist in large scale biofuel production from wild-type and genetically modified Synechocystis PCC 6803 strains by (1) efficient harvesting of cyanobacterial cells and (2) producing of high yields of lipids accumulated in fungal-cyanobacterial pellets.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Sciences, Royal Melbourne Institute of Technology University, Bundoora, VIC 3083 Australia.

ABSTRACT

Background: Numerous strategies have evolved recently for the generation of genetically modified or synthetic microalgae and cyanobacteria designed for production of ethanol, biodiesel and other fuels. In spite of their obvious attractiveness there are still a number of challenges that can affect their economic viability: the high costs associated with (1) harvesting, which can account for up to 50 % of the total biofuel's cost, (2) nutrients supply and (3) oil extraction. Fungal-assisted bio-flocculation of microalgae is gaining increasing attention due to its high efficiency, no need for added chemicals and low energy inputs. The implementation of renewable alternative carbon, nitrogen and phosphorus sources from agricultural wastes and wastewaters for growing algae and fungi makes this strategy economically attractive.

Results: This work demonstrates that the filamentous fungi, Aspergillus fumigatus can efficiently flocculate the unicellular cyanobacteria Synechocystis PCC 6803 and its genetically modified derivatives that have been altered to enable secretion of free fatty acids into growth media. Secreted free fatty acids are potentially used by fungal cells as a carbon source for growth and ex-novo production of lipids. For most of genetically modified strains the total lipid yields extracted from the fungal-cyanobacterial pellets were found to be higher than additive yields of lipids and total free fatty acids produced by fungal and Synechocystis components when grown in mono-cultures. The synergistic effect observed in fungal-Synechocystis associations was also found in bioremediation rates when animal husbandry wastewater was used an alternative source of nitrogen and phosphorus.

Conclusion: Fungal assisted flocculation can complement and assist in large scale biofuel production from wild-type and genetically modified Synechocystis PCC 6803 strains by (1) efficient harvesting of cyanobacterial cells and (2) producing of high yields of lipids accumulated in fungal-cyanobacterial pellets.

No MeSH data available.