Genomics of microalgae, fuel for the future?

Rising sea levels, global pollution, economic meltdown and general prophecies of doom and gloom are inspired by the pending depletion of the world fossil carbon stores. With modern lifestyle on the rise, and an ever increasing world population driven on by economic advantage, we burn up earth's stores of mineralized corpses and vent CO2 as if there is no tomorrow. The billion dollar question for our society is: Where to get the next big, and prefer- ably clean, fuel injection? Fossil carbon compounds, the incompletely biodegraded remains of animals and plants long gone, originate from atmospheric CO2 via photosyn- thesis. Therefore, photosynthesis as main driver for gen- eration of de novo fuels has gained attention. First- and second-generation biofuels envision the conversion of plant biomass via the action of microorganisms, into usable organic compounds (alcohols and fats) and hydro- gen. However, water and land misuse, deforestation, and rising food prices, for the sake of growing choice biomass- producing crops, have raised major concerns (Frow et al., 2009; Young, 2009). Third-generation biofuels (and chemicals) produced with microalgae have now come forward as an answer to many of these concerns (Tredici, 2010). In general, microalgae do not comprise an evolu- tionarily related group, and may refer to cyanobacteria (blue-green algae) or eukaryotic algae. Even the eukary- otic algae do not form a single evolutionary branch as it can be used to indicate 'plant algae' such as red algae (Rhodophyta), brown algae (Phaetophyta) and green algae (Chlorophyta) or diatoms (Fig. 1). Some species of microalgae naturally accumulate vast quantities of oils, some above 80% dry-weight (Fig. 2). In comparison, agricultural oil-producing crops such as palm oil and soybean rarely produce more than 5% dry-weight in oils. Furthermore, algae can be grown everywhere where there is plenty of water and sun (including lakes or in the sea) and thus are not necessarily restricted to (or compete with) areas with arable land. Combined with their fast growth rate, microalgae are considered one of the few realistic sources for the production of biofuels and supe- rior to agricultural crop-derived bioethanol (Chisti, 2007; Tredici, 2010). Indeed, in 2009 ExxonMobil pledged $600 million for research in support of photosynthetic algae biofuels programmes, including Craig Venter's Synthetic Genomics. This signals a growing interest in de novo photosynthesis-derived fuels even by established oil- producing companies. Here we present a genomics update of some of Mother Nature's finest microorganisms which can make 'something from nothing' with a breath of CO2, a gulp of water, and all the while basking in the sun. Meet the cyanobacteria, green algae and (photosynthetic) diatoms that may lend a helping hand to fuel the human race.