In order to produce biofuels from micro-algae we will have to generate high yields, so we need to know which strains will produce the most oil. While there is a lot of work being done on micro-algae biotechnology—currently around 10,000 researchers across the world—no-one has identified a shortlist of the best performing strains and how their properties could be used.

—lead author Dr. Stephen Slocombe, Scottish Association for Marine Science (SAMS)

In addition to strains for making biofuel, the report also signposts those which could be used as sources of food, Omega-3 oils, or aquaculture feed.

The principal aim of this study was to identify a suite of model strains for large scale/low cost biotech purposes such as biodiesel, biogas and added-value nutraceutical feeds. The focus was on strains capable of good growth at seawater salinity, with somewhat low nitrate and phosphate levels and no CO₂ supplementation. This reflected the high economic cost of providing fertilizer and CO₂ at large scale. Growth conditions were standardized in order to set a baseline with which to make a comparative analysis of the strains. A further goal was to investigate the partitioning of resources in algae; such a comparative dataset could also be linked to omic and phylogenetic data-sets in the future. A final aim was to improve methodological strategies and facilitate larger-scale screening.

The two highest lipid producers were Nannochloropsis oceanica CCAP 849/10 and a marine Chlorella vulgaris CCAP 211/21A strain. The former was originally isolated from a fish hatchery and, since many freshwater Chlorella are already commercially exploited, it is likely that both strains would be robust enough for use in open-air ponds. This Chlorella is the first salt-tolerant strain with noted potential and the TFA content observed (52% DW) is similar to some of the higher reported levels in the literature for its freshwater relatives (48-57% DW; gravimetric measurements of total lipid).

… The FA composition of lipids from Nannochloropsis species, along with sunflower and Canola, are more suited for biodiesel production. A detailed analysis of 12 different Nannochloropsis strains from 4 species found that N. oceanica strains had significantly higher TFA productivity and content than the others tested.

—Slocombe et al.

BioMara was a joint UK and Irish project aiming to demonstrate the feasibility and viability of producing third generation biofuels from marine biomass.

Resources

• Stephen P. Slocombe, QianYi Zhang, Michael Ross, Avril Anderson, Naomi J. Thomas, Ángela Lapresa, Cecilia Rad-Menéndez, Christine N. Campbell, Kenneth D. Black, Michele S. Stanley & John G. Day (2015) “Unlocking nature’s treasure-chest: screening for oleaginous algae” Scientific Reports 5, Article number: 9844 doi: 10.1038/srep09844