冷冻保存是厌氧氨氧化颗粒污泥(AnGS)保存的有效方法之一。然而,冷却预处理对AnGS的影响尚不清楚。在这项研究中,通过设计不同的冷却模式,研究了温度降低对AnGS性能的影响:在室温20-25°C(CK)下恒定,急剧冷却至4°C(S4),-20°C(S20)并逐步冷却至4°C(A4),-20°C(A20)。结果表明,与CK相比,S4,S20,A4和A20中的冷却模式提高了AnGS的物理保存能力,减缓颜色的变化,形状和结构;并提高了功能细菌Planctomycetes(门水平)和念珠菌(属水平)的保存率。不同实验组的活细胞保存率为48.4±1.8%(CK),61.1±3.3%(S4),37.8±0.8%(S20),81.7±4.8%(A4),61.9±3.1%(A20),分别。发现逐步冷却模式(A4和A20)的厌氧氨氧化细菌(AnAOB)进入休眠状态并形成“休眠状态”,同时观察到处于急剧冷却模式(S4和S20)的AnAOB进入冲击状态,但变化不大。这项工作的发现(尤其是AnAOB的休眠状态)有助于了解温度下降对AnGS的影响并促进AnGS保存技术的发展。
Cryopreservation is one of the effective methods for the preservation of anammox granular sludge (AnGS). However, the effects of cooling pretreatment on AnGS are still unclear. In this study, the effects of temperature decrease on AnGS property were investigated by designing different cooling modes: constant at room temperature 20-25 °C (CK), sharp cooling to 4 °C (S4), -20 °C (S20) and stepwise cooling to 4 °C (A4), -20 °C (A20). The results showed that compared with CK, the cooling modes in S4, S20, A4 and A20 improved the physical preservability of AnGS, slowing down the changes of color, shape and structure; and elevated the preservation rate of functional bacteria Planctomycetes (phylum level) and Candidatus Brocadia (genus level). The preservation rate of live cells in different experimental groups was 48.4 ± 1.8%(CK), 61.1 ± 3.3%(S4), 37.8 ± 0.8%(S20), 81.7 ± 4.8%(A4), 61.9 ± 3.1%(A20), respectively. The Anaerobic Ammonium Oxidation Bacteria (AnAOB) in the stepwise cooling mode (A4 and A20) were found to enter the dormant state and form \"dormant zoogloea\", while the AnAOB in the sharp cooling mode (S4 and S20) were observed to enter the shock state with a little change. The findings in this work (especially the dormant state of AnAOB) are helpful to understand the effect of temperature decrease on AnGS and to promote the development of AnGS preservation technology.