Article

Treatment of Phaeodactylum tricornutum cells with papain facilitates lipid extraction.

Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK. Electronic address: .
Journal of Biotechnology (Impact Factor: 3.18). 07/2012; 162(1):40-9. DOI: 10.1016/j.jbiotec.2012.06.033
Source: PubMed

ABSTRACT Triacylglycerols (TAGs) from microalgae have the potential to be used for biodiesel, but several technical and economic hurdles have to be overcome. A major challenge is efficient extraction of intracellular TAGs from algae. Here we investigate the use of enzymes to deconstruct algal cell walls/membranes. We describe a rapid and simple assay that can assess the efficacy of different enzyme treatments on TAG-containing algae. By this means crude papain and bromelain were found to be effective in releasing TAGs from the diatom Phaeodactylum tricornutum, most likely because of their cysteine protease activity. Pre-treating algal biomass with crude papain enabled complete extraction of TAGs using heptane/isopropyl alcohol. Heptane as a single solvent was also effective, although complete recovery of TAG was not obtained. Economic implications of these findings are discussed, with the aim to reduce the complexity of, and energy needed in, TAG extraction.

0 Bookmarks
 · 
159 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area.
    Trends in Biotechnology 02/2014; · 10.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A life cycle assessment (LCA) was performed on a putative biodiesel production plant in which the freshwater alga Chlorella vulgaris, was grown using an existing system similar to a published commercial-scale hybrid cultivation. The hybrid system couples airlift tubular photobioreactors with raceway ponds in a two-stage process for high biomass growth and lipid accumulation. The results show that microalgal biodiesel production would have a significantly lower environmental impact than fossil-derived diesel. Based on the functional unit of 1 ton of biodiesel produced, the hybrid cultivation system and hypothetical downstream process (base case) would have 42% and 38% savings in global warming potential (GWP) and fossil-energy requirements (FER) when compared to fossil-derived diesel, respectively. Sensitivity analysis was performed to identify the most influential process parameters on the LCA results. The maximum reduction in GWP and FER was observed under mixotrophic growth conditions with savings of 76% and 75% when compared to conventional diesel, respectively.
    Bioresource Technology 04/2014; 163C:343-355. · 5.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To improve the economic viability of microalgal biodiesel, it will be essential to optimize productivity of fuel molecules such as triacylglyceride (TAG) within the microalgal cell. To understand some of the triggers required for the metabolic switch to TAG production, we studied the effect of carbon supply (acetate or CO2) in Chlamydomonas reinhardtii (wild type and the starch-less mutant sta6) grown under low N availability. As expected, initial rates of TAG production were much higher when acetate was present, compared to strictly photosynthetic conditions, particularly for sta6, which cannot allocate resources to starch. However, in both strains TAG production plateaued after a few days in mixotrophic cultures, whereas under autotrophic conditions TAG levels continued to rise. Moreover, the reduced growth of sta6 meant that the greatest productivity (measured as mg TAG L(-1) day(-1)) was found in wild type growing autotrophically. Wild type cells responded to low N by autophagy, as shown by degradation of polar (membrane) lipids and loss of photosynthetic pigments, and this was less in cells supplied with acetate. In contrast little or no autophagy was observed in sta6 cells regardless of carbon supply. Instead, very high levels of free fatty acids were observed in sta6, suggesting considerable alteration in metabolism. These measurements show the importance of carbon supply and strain selection for lipid productivity. Our findings will be of use for industrial cultivation, where it will be preferable to use fast-growing wild type strains supplied with gaseous CO2 under autotrophic conditions, rather than requiring an exogenous supply of organic carbon.
    Eukaryotic Cell 01/2014; · 3.18 Impact Factor

Full-text

Download
99 Downloads
Available from
May 15, 2014