Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido 060-8628, Japan.
Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido 060-8628, Japan; Water Desalination and Reuse Center (WDRC), Biological and Environmental Science and Engineering (BESE) Divison, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Water Res. 2017 Jun 1;116:296-303. doi: 10.1016/j.watres.2017.03.027. Epub 2017 Mar 14.
Anammox bacteria have long been considered to be slow-growing bacteria. However, it has recently been reported that they could grow much faster than previously thought when they were cultivated in a membrane bioreactor (MBR) with a step-wise decrease in the solid retention time (SRT). Here, we reevaluated the maximum specific growth rates (μ) of three phylogenetically distant anammox bacterial species (i.e. "Ca. Brocadia sinica", "Ca. Jettenia caeni" and "Ca. Scalindua sp.") by directly measuring 16S rRNA gene copy numbers using newly developed quantitative polymerase chain reaction (qPCR) assays. When free-living planktonic "Ca. B. sinica" and "Ca. J. caeni" cells were immobilized in polyvinyl alcohol (PVA) and sodium alginate (SA) gel beads and cultivated in an up-flow column reactor with high substrate loading rates at 37 °C, the μ were determined to be 0.33 ± 0.02 d and 0.18 d (corresponding doubling time of 2.1 day and 3.9 day) from the exponential increases in 16S rRNA genes copy numbers, respectively. These values were faster than the fastest growth rates reported for these species so far. The cultivation of anammox bacteria in gel beads was achieved less than one month without special cultivation method and selection pressure, and the exponential increase in 16S rRNA gene numbers was directly measured by qPCR with high reproducibility; therefore, the resulting μ values were considered accurate. Taken together, the fast growth is, therefore, considered to be an intrinsic kinetic property of anammox bacteria.
氨氧化菌长期以来被认为是生长缓慢的细菌。然而，最近有报道称，当它们在膜生物反应器（MBR）中培养时，随着固体停留时间（SRT）逐步降低，氨氧化菌的生长速度可以比以前想象的快得多。在这里，我们通过使用新开发的定量聚合酶链反应（qPCR）测定法直接测量 16S rRNA 基因拷贝数，重新评估了三种系统发育上不同的氨氧化细菌（即“Ca. Brocadia sinica”、“Ca. Jettenia caeni”和“Ca. Scalindua sp.”）的最大比生长速率（μ）。当自由生活的浮游“Ca. B. sinica”和“Ca. J. caeni”细胞被固定在聚乙烯醇（PVA）和海藻酸钠（SA）凝胶珠中，并在 37°C 下以高基质负荷率在上升流柱反应器中培养时，从 16S rRNA 基因拷贝数的指数增加中确定μ分别为 0.33±0.02 d 和 0.18 d（相应的倍增时间为 2.1 天和 3.9 天）。这些值比迄今为止报道的这些物种的最快生长速率还要快。在没有特殊培养方法和选择压力的情况下，在凝胶珠中培养氨氧化菌不到一个月就实现了，并且通过具有高重现性的 qPCR 直接测量了 16S rRNA 基因数量的指数增加；因此，得到的μ值被认为是准确的。综上所述，快速生长被认为是氨氧化菌的固有动力学特性。
