From wetlands to wastewater: leveraging natural biomes to determine key factors for engineering stable biological processes

废物管理和可再生能源是加拿大可持续性和减排的重大挑战。厌氧消化(AD)过程通过细菌和其他微生物的组合活动将废物分解成沼气(甲烷和二氧化碳)来满足这两种需求。目前，加拿大只有13%的潜在沼气产量通过AD获得。AD的广泛应用受到限制，部分原因是甲烷(用于能源的沼气部分)产量不一致。AD系统内微生物之间的相互作用在暴露于条件和毒素中断时的不稳定性是甲烷产量的一个关键因素。废物管理中的一项新兴战略是通过湿废物的水热液化(HTL)来减少废物体积，以生产生物粗燃料。HTL的液体副产物含有许多已知可促进AD中甲烷产生的化合物，即挥发性脂肪酸。然而，HTL的副产物也含有许多大多数AD系统中的微生物不能容忍的毒素，并扰乱了系统的稳定性，降低了总体甲烷产量。HTL副产物的价态对于HTL生产生物粗品的经济可行性至关重要，正如更广泛地实施AD需要更稳定的微生物系统一样。湿地是AD过程的天然类似物，是地球上甲烷产量最高的环境之一。来自溪流和河流的水聚集在湿地中，经常导致有毒化合物的积聚。因此，湿地可能含有对这些毒素有很高耐受性的微生物。虽然为工程系统提供稳定性的天然微生物群落的使用越来越多，但如果这种方法要在工程微生物过程中大规模实施，这种稳定性的机制仍然没有解决。这项发现拨款旨在通过解决工程微生物系统稳定性的特定因素，为AD和HTL技术的更广泛使用铺平道路。这将通过利用湿地沉积物中的微生物构建和研究模型微生物系统来测试有助于微生物相互作用稳定性的三个特定因素：1)耐受各种有毒化合物的代谢能力，2)微生物多样性：微生物物种内可能允许在变化的条件下生存的微小遗传变异3)噬菌体的存在：感染并杀死特定微生物的病毒。在开发一种从湿地中选择耐受毒素的微生物的过程中，我们正在构建一个模型系统，可用于测试AD过程稳定性的特定因素。这种方法将提供基础和应用知识，同时培训学生和研究人员在快速增长的工程微生物系统领域。

Waste management and renewable energy represent critical challenges for sustainability and emissions reduction in Canada. The process of anaerobic digestion (AD) addresses both of these needs through the combined activities of bacteria and other microbes in the break down of waste into biogas (methane and carbon dioxide) for energy. Currently Canada accesses only 13% of its potential biogas production via AD. Wider application of AD is limited in part because of the inconsistency in methane (the portion of biogas used for energy) yield. The instability of the interactions between the microbes within AD systems when exposed to disruptions in conditions and toxins is a key factor in methane yield. An emerging strategy in waste management is the reduction of waste volume by hydrothermal liquefaction (HTL) of wet waste for production of biocrude fuel. Liquid by-products of HTL contain many compounds known to boost methane production in AD, namely volatile fatty acids. However, HTL by-products also contain many toxins which are not tolerated by the microbes in most AD systems, and disrupt the stability of the system, reducing overall methane yield. Valorization of HTL by-products is critical for the economic viability of biocrude production by HTL, just as greater stability of microbial systems is needed for wider implementation of AD. Wetlands are a natural analogue for AD processes, and are among the highest methane producing environments on the planet. Water from streams and rivers collect in wetlands, often causing the build-up of toxic compounds. As such, wetlands and may contain microbes with a high potential to tolerate these toxins. While sourcing natural microbial communities to supply stability to engineered systems is growing in use, the mechanisms of this stability remain unresolved if this approach is to be implemented at scale in engineered microbial processes. This Discovery Grant aims to build a path toward wider use of AD and HTL technologies by addressing specific factors underlying the stability of engineered microbial systems. This will be achieved through construction and study of a model microbial system with microbes from wetland sediments to test three specific factors that contribute the stability of microbial interactions: 1) The metabolic capacity to tolerate various toxic compounds, 2) Microdiversity: small genetic variation within microbial species that may allow for survival in changing conditions 3) Presence of phage: viruses that infect and kill specific microbes. In developing a process to select for microbes from wetland that tolerate toxins, we are constructing a model system that can be used to test the specific factors underlying stability of AD processes. This approach will provide both fundamental and applied knowledge while training students and researchers in the rapidly growing area of engineered microbial systems.