Krustok I, Truu J, Odlare M, Truu M, Ligi T, Tiirik K, Nehrenheim E
School of Business, Society and Engineering, Mälardalen University, P.O. Box 883, SE-721 23, Västerås, Sweden,
Appl Microbiol Biotechnol. 2015 Aug;99(15):6537-49. doi: 10.1007/s00253-015-6580-7. Epub 2015 Apr 21.
Photobioreactors are a novel environmental technology that can produce biofuels with the simultaneous removal of nutrients and pollutants from wastewaters. The aim of this study was to evaluate the effect of lake water inoculation on the production of algal biomass and phylogenetic and functional structure of the algal and bacterial communities in municipal wastewater-treating lab-scale photobioreactors. Inoculating the reactors with lake water had a significant benefit to the overall algal biomass growth and nutrient reduction in the reactors with wastewater and lake water (ratio 70/30 v/v). The metagenome-based survey showed that the most abundant algal phylum in these reactors was Chlorophyta with Scenedesmus being the most prominent genus. The most abundant bacterial phyla were Proteobacteria and Bacteroidetes with most dominant families being Sphingobacteriaceae, Cytophagaceae, Flavobacteriaceae, Comamonadaceae, Planctomycetaceae, Nocardiaceae and Nostocaceae. These photobioreactors were also effective in reducing the overall amount of pathogens in wastewater compared to reactors with wastewater/tap water mixture. Functional analysis of the photobioreactor metagenomes revealed an increase in relative abundance genes related to photosynthesis, synthesis of vitamins important for auxotrophic algae and decrease in virulence and nitrogen metabolism subsystems in lake water reactors. The results of the study indicate that adding lake water to the wastewater-based photobioreactor leads to an altered bacterial community phylogenetic and functional structure that could be linked to higher algal biomass production, as well as to enhanced nutrient and pathogen reduction in these reactors.
光生物反应器是一种新型环境技术，能够在从废水中去除营养物质和污染物的同时生产生物燃料。本研究的目的是评估接种湖水对城市污水处理实验室规模光生物反应器中藻类生物质产量以及藻类和细菌群落的系统发育和功能结构的影响。用湖水接种反应器对含废水和湖水（体积比70/30）的反应器中藻类生物质的总体生长和营养物质减少具有显著益处。基于宏基因组的调查显示，这些反应器中最丰富的藻类门是绿藻门，其中栅藻属最为突出。最丰富的细菌门是变形菌门和拟杆菌门，最主要的科是鞘脂杆菌科、噬纤维菌科、黄杆菌科、丛毛单胞菌科、浮霉菌科、诺卡氏菌科和念珠藻科。与含废水/自来水混合物的反应器相比，这些光生物反应器在减少废水中病原体总量方面也很有效。对光生物反应器宏基因组的功能分析表明，与光合作用、对营养缺陷型藻类重要的维生素合成相关的基因相对丰度增加，而湖水反应器中毒力和氮代谢子系统减少。研究结果表明，向以废水为基础的光生物反应器中添加湖水会导致细菌群落的系统发育和功能结构发生改变，这可能与更高的藻类生物质产量以及这些反应器中营养物质和病原体减少的增强有关。
