Harnessing biodegradable plastics from microalgae cultivated on recalcitrant waste streams

在全球范围内，每年大约生产3亿吨塑料。这些塑料中只有一小部分被回收，而更多的塑料最终成为废物。垃圾填埋场、水资源、湖泊、河流和海洋中的塑料是一个严重且日益严重的问题。特别令人关注的是微塑料(直径小于5毫米的塑料颗粒)，它可被海洋生物摄取，危及其生命，并导致各种下游环境问题。在加拿大，大约1500亿升未经处理或未处理的废水被引入加拿大的水道。废水排放到环境中是有害藻华(HABS)的主要原因之一，它对人类、鱼类和水道产生有毒影响，每年造成数亿美元的经济损失。这项战略赠款的总体目标是开发新的战略，从废水流中培养的微藻中收获可生物降解的塑料，从而同时解决两个严重的环境问题。具体地说，在这项研究中，(A)我们调查了利用藻类生产生物复合塑料(利用奶牛场的污水培养)；(B)我们调查了单体衣康酸在基于微藻的表达系统中的表达；以及(3)我们评估了将从农场污水流中生长的转基因藻类产生的衣康酸用于制备新型可生物降解聚合物的新方法的开发。在这个研究项目中，我们与当地一家大型奶牛场密切合作，利用好氧和厌氧消化器的流出物作为微藻生物塑料的基质。利用重组微藻收获藻类纤维复合材料和衣康酸，并最终生产出可生物降解的常规塑料片段，将产生具有经济竞争力的生物产品，具有社会、环境和经济效益。拟议的研究将为发展农村经济带来新的机遇，并培养这些领域的高素质人才。

Approximately 300 million tons of plastics are produced annually on a global scale. Only a fraction of these plastics are recycled and a much larger amount ends up as waste. Plastics in landfills, in water resources, lakes, rivers, and oceans are a serious and growing issue. Of particular concern are micro-plastics (particles of plastic less than 5 mm in diameter), which can be ingested by marine organisms, endangering their life and leading to various downstream environmental problems. In Canada, around 150 billion litres of untreated or under-treated wastewater are introduced into Canadian waterways. The discharge of wastewater into the environment is one of the major causes of harmful algal blooms (HABs), which can have toxic effects on humans, fish, and waterways and economic losses in hundreds of millions of dollars annually. The overall objectives of this strategic grant are to develop new strategies for harvesting biodegradable plastics from microalgae cultivated on wastewater streams, thus, addressing two serious environmental issues simultaneously. Specifically, in this research, (a) we investigate the production of bio-composite plastics from algae ( which are cultured on effluents from a dairy farm); (b) we investigate the expression of the monomer itaconic acid in microalgal-based expression systems; and (3) we evaluate the development of new approaches to use itaconic acid produced from genetically modifed algae grown on farm effluent streams for the preparation of new biodegradable polymers. We work closely in this research project with a large, local dairy farm, utilizing effluent streams from aerobic and anaerobic digesters as substrates for microalgal bioplastics. The research using recombinant microalgae to harvest algal-fiber composites and itaconic acid and ultimately produce biodegradable segments in conventional plastics will lead to economically competitive bio-products which will benefit society, the environment and the economy. The proposed research will lead to new opportunities to develop the rural economy and also train highly qualified personnel in these fields.