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

二十年前，人们提出了通过脂质酯交换来大规模生产光合绿色微藻，这是第三代生物燃料（生物柴油）的令人兴奋的前景。然而，生物柴油的大规模生产还没有真正经济，部分原因是提供足够的二氧化碳来提高生产率。为了解决这个问题，微藻提供了机会，以减少温室气体二氧化碳在工业废气中使用它作为他们的主要碳源-然而，酸性成分的存在，许多工业废气可以抑制微藻生产力通过降低pH值的介质中生长。 加拿大有超过31，000个淡水湖，是世界上最大的未开发的光合微藻资源来源。此外，自19世纪世纪以来，一直有广泛的矿山勘探，特别是在北部，历史上缺乏矿山关闭计划，这意味着许多矿山留下了重大的遗产，如酸性矿山排水（AMD）影响水体。目前，这些设备没有使用后价值，实际上往往被视为一种负债。加拿大有7500多个废弃的矿场，估计造成了100亿美元的环境责任。 由于AMD导致高金属浓度和低pH值，这些条件可能导致生态系统破坏和微藻选择性，但也可能导致所需微藻特性（对废气暴露导致的低pH值的抗性）和更高水平的有价值的保护性次级代谢产物的表达。这些代谢物包括适合于酯交换成用于生物柴油的脂肪酸甲酯（FAME）的脂质（脂肪酸），但也包括其他期望的化合物，例如多不饱和脂肪酸（例如ω 3）、类胡萝卜素和聚酮化合物。我们还发现微藻提取物显示出非常显著的抗菌活性和抗癌活性。因此，对低pH值的抗性以及脂质和其他增值代谢物的共同生产可以显著帮助微藻大规模生产的经济性。这项研究的最终目标是通过制定如何绘制一条路线来建设性地利用非生产性场地，受影响的水体和温室气体排放来帮助设计社会效益。为了做到这一点，它将首次进行生物勘探，并对加拿大北方紧张环境中的土著微藻物种进行表征，并分离出那些表现出极有价值的性状和特征的物种。此外，它将研究如何减少区域废气来源中的二氧化碳，以提高选定的生物勘探微藻的产量，并随后最大限度地表达所需的代谢产物。从长远来看，这种综合办法将提供从其他非生产性资源中获得新的经济机会的可能性，特别是对加拿大北方各地的小型和偏远社区。

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.