Data_Sheet_1_Identification of Microbiological Activities in Wet Flue Gas Desulfurization Systems.docx

Thermoelectric power generation from coal requires large amounts of water, much of which is used for wet flue gas desulfurization (wFGD) systems that minimize sulfur emissions, and consequently, acid rain. The microbial communities in wFGDs and throughout thermoelectric power plants can influence system performance, waste processing, and the long term stewardship of residual wastes. Any microorganisms that survive in wFGD slurries must tolerate high total dissolved solids concentrations (TDS) and temperatures (50–60°C), but the inocula for wFGDs are typically from fresh surface waters (e.g., lakes or rivers) of low TDS and temperatures, and whose activity might be limited under the physicochemically extreme conditions of the wFGD. To determine the extents of microbiological activities in wFGDs, we examined the microbial activities and communities associated with three wFGDs. O2 consumption rates of three wFGD slurries were optimal at 55°C, and living cells could be detected microscopically, indicating that living and active communities of organisms were present in the wFGD and could metabolize at the high temperature of the wFGD. A 16S rRNA gene-based survey revealed that the wFGD-associated microbial communities included taxa attributable to both thermophilic and mesophilic lineages. Metatranscriptomic analysis of one of the wFGDs indicated an abundance of active Burholderiaceae and several Gammaproteobacteria, and production of transcripts associated with carbohydrate metabolism, osmotic stress response, as well as phage, prophages, and transposable elements. These results illustrate that microbial activities can be sustained in physicochemically extreme wFGDs, and these activities may influence the performance and environmental impacts of thermoelectric power plants.

燃煤火力发电需消耗大量水资源，其中大部分用于湿法烟气脱硫（wet flue gas desulfurization, wFGD）系统，该系统可削减硫排放，从而减轻酸雨危害。湿法烟气脱硫系统乃至整个热电厂内的微生物群落，可对系统运行性能、废弃物处理以及残余废物的长期管理产生影响。湿法烟气脱硫浆液中存活的所有微生物，均需耐受极高的总溶解固体（total dissolved solids, TDS）浓度与50~60℃的高温，但湿法烟气脱硫系统的接种菌种通常来自低总溶解固体、低温的新鲜地表水（如湖泊或河流），这些菌种在湿法烟气脱硫系统的极端物化条件下，其活性可能受到抑制。为探明湿法烟气脱硫系统内微生物活动的规模与程度，我们对三个湿法烟气脱硫系统相关的微生物活性与群落结构开展了检测分析。三个湿法烟气脱硫浆液的耗氧速率在55℃时达到峰值，且通过显微镜可观测到活体细胞，这表明湿法烟气脱硫系统内存在具有代谢活性的活体微生物群落，且可在系统高温环境下进行代谢活动。基于16S核糖体RNA基因（16S rRNA gene）的测序调查显示，与湿法烟气脱硫系统相关的微生物群落包含嗜热与中温两个演化类群的分类单元。对其中一个湿法烟气脱硫系统的宏转录组分析（metatranscriptomic analysis）结果显示，活跃的伯克霍尔德菌科（Burholderiaceae）与数种γ-变形菌纲（Gammaproteobacteria）物种丰度较高，同时存在与碳水化合物代谢、渗透压应激响应以及噬菌体、前噬菌体和转座因子相关的转录本表达。上述结果表明，在极端物化条件的湿法烟气脱硫系统中仍可维持微生物活动，而这些活动可能会对热电厂的运行性能与环境影响产生作用。