Photoheterotrophy for economical production of bioplastics from municipal organic waste: Integration of polyphosphate metabolism and P-recovery chemistry to maximize PHA yields

城市污水和有机固体废物行业正在经历一场资源回收革命。从废物中生产有用的生物材料有望带来巨大的经济和环境效益。要生产的重要生物材料包括生物塑料前体聚羟基烷酸(PHA)，以及用于化肥的磷(P)矿物碳酸盐磷灰石(即磷矿)。我们将开发一种新的利用红外的高效混合微生物工艺--利用光异养紫色非硫细菌(PNSB)合成PHA并浓缩磷；然后应用结晶理论来捕获磷。目前对PHA生产的技术经济研究表明，混合培养物比以无菌饲料喂养的纯培养物更经济。因此，我们的项目将提供成本降低，并最终产品的多功能性。我们的工业合作伙伴将获得基于PNSB的颠覆性技术的新知识，以继续开发未来的产品线，并为回收的资源提供几个市场渠道。加拿大污水处理设施将获得适应寒冷冬季的高效资源回收工艺。加拿大还将受益于用于化肥生产的可再生磷来源，因为加拿大唯一的磷矿于2013年关闭。这些新进程将有助于减少温室气体排放，并帮助加拿大实现其可持续发展和粮食安全目标。建议的工艺将利用高效的光营养PNSB新陈代谢来浓缩磷并从稀释的城市污水中生产生物质。在废水中生长的PNSB生物量将利用一种新的高强度光照方法来丰富PHA的积累，这也将诱导聚磷酸盐的积累。在单独的步骤中，聚磷酸盐将从PNSB中释放出来，并被新的碳酸盐磷灰石结晶过程捕获。磷限制的生物质将用于利用有机废物发酵产生的挥发性脂肪酸合成PHA。拟议的研究将阐明PNSB最大限度地提高PHA和聚磷酸盐积累代谢的合适反应器条件。该项目将培养12名HQP：2名博士，3名孟晚舟，1名博士后，6名本科生。

The municipal wastewater and organic solids waste industries are undergoing a resource recovery revolution. Producing useful biomaterials from wastes promises great economic and environment benefits. Important biomaterials to produce include the bioplastic precursor polyhydroxyalkanoate (PHA), and the phosphorus (P) mineral carbonate apatite (i.e., phosphate rock) used in fertilizers. We will develop a new highly efficient mixed microbial process harnessing infrared-using photoheterotrophic purple non-sulfur bacteria (PNSB) to synthesize PHA and concentrate P; then, to apply crystallization theory for P capture. Current techno-economic studies of PHA production suggest that mixed cultures are more economical than pure cultures fed sterilized feedstocks. Thus, our project will provide cost reduction, and end-product versatility. Our industrial partner will gain new knowledge of PNSB-based disruptive technologies to continue developing future product lines with several market outlets for recovered resources. Canadian wastewater treatment facilities will gain an efficient resource recovery processes adapted to cold winters. Canada would also benefit from a renewable source of P for fertilizer production, as the only Canadian phosphate mine closed in 2013. These new processes will help reduce greenhouse gas emissions and help Canada meet its sustainability and food security targets. The proposed process will take advantage of the efficient photoherotrophic PNSB metabolism to concentrate phosphate and produce biomass from dilute municipal wastewater. The PNSB biomass grown in wastewater will be enriched for PHA accumulation using a new high intensity illumination method, which will also induce the accumulation of polyphosphate. In a separate step, the polyphosphate will be released from the PNSB and captured by a new carbonate apatite crystallization process. The P-limited biomass will be used for PHA synthesis using volatile fatty acids generated from the fermentation of organic waste. The proposed research will elucidate the proper reactor conditions to maximize the PHA and polyphosphate accumulation metabolisms by PNSB. The project will train a total of 12 HQP: 2 PhD, 3 MEng, 1 postdocs, and 6 undergrads.