Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, People's Republic of China.
National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, People's Republic of China.
Appl Microbiol Biotechnol. 2018 Feb;102(4):2019-2030. doi: 10.1007/s00253-017-8720-8. Epub 2018 Jan 18.
Enterobacter sp. strain FL was newly isolated from activated sludge and exhibited significant capability of auto-aggregation as well as aerobic denitrification. The removal efficiencies of NO-N, total nitrogen (TN), and TOC by strain FL in batch culture reached 94.6, 63.9, and 72.5% in 24 h, respectively. The production of NO and N in the presence of oxygen demonstrated the occurrence of aerobic denitrification. The auto-aggregation index of strain FL reached 54.3%, suggesting a high tendency that the cells would agglomerate into aggregates. The production of extracellular polymeric substances (EPSs), which were mainly composed of proteins followed by polysaccharides, was considered to be related to the cell aggregation according to Fourier transform infrared (FT-IR) and confocal laser scanning microscopy (CLSM). The proteins in EPS were evenly and tightly combined to cells and altered the protein secondary structures of cell surface from random coils to β-sheets and three-turn helices. The alteration of protein secondary structures of cell surface caused by the proteins in EPS might play a dominant role in the auto-aggregation of strain FL. To further assess the feasibility of strain FL for synthetic wastewater treatment, a sequencing batch reactor (SBR), solely inoculated with strain FL, was conducted. During the 16 running cycles, the removal efficiency of NO-N was 90.2-99.7% and the auto-aggregation index was stabilized at 35.0-41.5%. The EPS promoted the biomass of strain FL to aggregate in the SBR.
肠杆菌属菌株 FL 是从活性污泥中分离出来的，具有显著的自动聚集和有氧反硝化能力。在批式培养中，菌株 FL 在 24 h 内分别对 NO-N、总氮（TN）和 TOC 的去除效率达到 94.6%、63.9%和 72.5%。在有氧存在的情况下产生的 NO 和 N 表明有氧反硝化的发生。菌株 FL 的自动聚集指数达到 54.3%，表明细胞聚集形成聚集体的趋势很高。胞外聚合物（EPS）的产生，主要由蛋白质组成，其次是多糖，根据傅里叶变换红外（FT-IR）和共聚焦激光扫描显微镜（CLSM），被认为与细胞聚集有关。EPS 中的蛋白质均匀且紧密地结合到细胞上，并改变了细胞表面的蛋白质二级结构从无规卷曲到β-折叠和三转角螺旋。EPS 中的蛋白质引起的细胞表面蛋白质二级结构的改变可能在菌株 FL 的自动聚集中起主导作用。为了进一步评估菌株 FL 用于合成废水处理的可行性，单独接种菌株 FL 的序批式反应器（SBR）进行了。在 16 个运行周期中，NO-N 的去除效率为 90.2%-99.7%，自动聚集指数稳定在 35.0%-41.5%。EPS 促进了 SBR 中菌株 FL 的生物量聚集。
