The depletion of oil reserves has led to the development of renewable alternatives to petroleum products such as biodiesel. Historically, biodiesel has been extracted from vegetable oil or animal fats by reacting with alcohol to produce alkyl esters that can be used in conventional engines. However, producing biodiesel from the food chain competes with agricultural land use for food production.
Biotechnological research into biodiesel production therefore focusses on breeding crops for high lipid content, whilst the cultivation of algae, yeasts and other microbes are increasingly explored as a source of lipids. BioMed Central’s biotechnology journals showcase the latest research in renewable lipid and biodiesel production.
In Biotechnology for Biofuels, Abdullah et al. present a transcriptome analysis of Camelina sativa, an emerging oilseed crop for biodiesel production to identify gene networks associated with triacylglycerol (TAG) biosynthesis, with a view to future genetic improvement of strains to produce more lipids.
Xue et al., write in Microbial Cell Factories about engineering a Chlorella algal strain to increase malic enzyme activity and subsequent lipid accumulation with potential applications in biodiesel production.
Reporting in BMC Biotechnology, Lamers et al. screen oleaginous yeasts to find a robust strain that can produce triacylglycerides from carbon sources, when triggered by nutrient limitation. In a similar vein, Signori et al. writing in Microbial Cell Factories, seek to optimise the growth of oleaginous yeast on crude glycerol, to avoid a lag phase in growth caused by impurities in the substrate.
Other microbes can also be persuaded to produce biodiesel including cyanobacteria Kato et al. present a strain of cyanobacteria, Synechococcus elongate, that excretes Free Fatty Acids into the culture medium, with the added benefit that lipids do not need to be extracted from the cells (an energy intensive step).
Many of these studies involve bioengineering of plants and microbes on a laboratory scale and the greatest challenge to producing renewable biodiesel is the scaling up of these novel synthetic technologies on an industrial scale.