Researchers are exploring whether these ubiquitous fluorinated molecules might worsen infections or hamper vaccine effectiveness.
Image credit: Shutterstock/Dmitry Naumov.
Edited by James L. Van Etten, University of Nebraska, Lincoln, NE, and approved October 29, 2013 (received for review May 16, 2013)
Significance
As global CO2 levels rise and fossil fuel abundance decreases, the development of alternative fuels becomes increasingly imperative. Biologically derived fuels, and specifically those from microalgae, are promising sources, but improvements throughout the production process are required to reduce cost. Increasing lipid yields in microalgae without compromising growth has great potential to improve economic feasibility. We report that disrupting lipid catabolism is a practical approach to increase lipid yields in microalgae without affecting growth or biomass. We developed transgenic strains through targeted metabolic engineering that show increased lipid accumulation, biomass, and lipid yields. The target enzyme’s ubiquity suggests that this approach can be applied broadly to improve the economic feasibility of algal biofuels in other groups of microalgae.
Abstract
Biologically derived fuels are viable alternatives to traditional fossil fuels, and microalgae are a particularly promising source, but improvements are required throughout the production process to increase productivity and reduce cost. Metabolic engineering to increase yields of biofuel-relevant lipids in these organisms without compromising growth is an important aspect of advancing economic feasibility. We report that the targeted knockdown of a multifunctional lipase/phospholipase/acyltransferase increased lipid yields without affecting growth in the diatom Thalassiosira pseudonana. Antisense-expressing knockdown strains 1A6 and 1B1 exhibited wild-type–like growth and increased lipid content under both continuous light and alternating light/dark conditions. Strains 1A6 and 1B1, respectively, contained 2.4- and 3.3-fold higher lipid content than wild-type during exponential growth, and 4.1- and 3.2-fold higher lipid content than wild-type after 40 h of silicon starvation. Analyses of fatty acids, lipid classes, and membrane stability in the transgenic strains suggest a role for this enzyme in membrane lipid turnover and lipid homeostasis. These results demonstrate that targeted metabolic manipulations can be used to increase lipid accumulation in eukaryotic microalgae without compromising growth.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: wgerwick{at}ucsd.edu.
Author contributions: E.M.T., R.P.S., M.H., and W.H.G. designed research; E.M.T., S.R.S., C.G., and A.C.H. performed research; S.R.S. contributed data and technical support; E.M.T., C.G., A.C.H., M.H., and W.H.G. analyzed data; M.H. and W.H.G. provided technical support; and E.M.T. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1309299110/-/DCSupplemental.
Freely available online through the PNAS open access option.
Disrupting lipid catabolism increases algal lipids
Article Classifications
- Biological Sciences
- Applied Biological Sciences
Sign up for Article Alerts
Jump to section
You May Also be Interested in
Recent experiments and simulations are starting to answer some fundamental questions about how life came to be.
Image credit: Shutterstock/Radoslaw Lecyk.
Archaeologists have long tried to define the transition between the two time periods.
Image credit: Ceri Shipton.
Adam Mastroianni and Daniel Gilbert explore why conversations almost never end when people want them to.
A study finds that giant pandas roll in horse manure to increase their cold tolerance.
Image credit: Fuwen Wei.