Capture and mitigation of small point source CO2 emissions using regional bioprospected microalgae

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Mass-production of photosynthetic green microalgae was put forward two decades ago as an exciting prospect for third-generation biofuels (biodiesel) through transesterification of their lipids. However, mass production of biodiesel has yet to be truly economic, in part due to supplying sufficient CO2 to boost productivity. To address this, microalgae offer the opportunity to mitigate the greenhouse gas CO2 in industrial off-gasses by using it as their primary carbon source - however, the presence of acid component to many industrial off-gasses can inhibit microalgal productivity by reducing the pH of medium they grow in. There over 31,000 freshwater lakes in Canada representing the World's largest untapped source of photosynthetic microalgae resources. Further, since the 19th century there has been extensive mine exploration, particularly across the north, and a historic lack of mine closure plans has meant that many left significant legacies, such as acid mine drainage (AMD) impacted water bodies. These currently offer no after-use value and indeed are often regarded a liability. There are more than 7500 abandoned mine sites across Canada representing an estiamated $10 billion in environmental liability. Stressed aquatic environments that have evolved due to AMD result in high metal concentrations and low pH. These conditions can lead to ecosystem disruption and microalgae selectivity, but also to expression of a desired microalgal characteristic (resistance to low pH resulting from exposure from off-gas) and greater levels of valuable protective secondary metabolites. These metabolites include lipids (fatty acids) suitable for transesterification into fatty acid methyl esters (FAMEs) for biodiesel, but also other desirable compounds such as polyunsaturated fatty acids (such as omega 3s), carotenoids and polyketides. We have also found microalgal extracts that exhibit very notable antibacterial activity and anticancer activities. Resistance to low pH and co-production of lipids and other value-adding metabolites could, therefore, significantly aid the economics of mass production of microalgae. The ultimate goal of this research is to help devise societal benefits by working out how to map a route to constructively utilize both non-productive sites, impacted water bodies, and greenhouse gas emissions. To do this, it will for the first-time bioprospect and characterize indigenous microalgal species from stressed environments in northern Canada, and isolate those that exhibit highly valuable traits and characteristics. Further, it will study how the CO2 in regional off-gas sources can be mitigated to enhance production of selected bioprospected microalgae, and subsequently maximize expression of desirable metabolites. For the long-term, this combined approach will offer the possibility of new economic opportunities from otherwise non-productive resources, especially for small and remote communities across northern Canada.