King Abdullah University of Science and Technology, Biological and Environmental Sciences and Engineering Division, Water Desalination and Reuse Center, Thuwal, 23955-6900, Saudi Arabia; Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West-8, Sapporo, Hokkaido, 060-8628, Japan.
King Abdullah University of Science and Technology, Biological and Environmental Sciences and Engineering Division, Water Desalination and Reuse Center, Thuwal, 23955-6900, Saudi Arabia.
Water Res. 2018 Oct 15;143:10-18. doi: 10.1016/j.watres.2018.06.007. Epub 2018 Jun 12.
Anaerobic ammonium-oxidizing (anammox) bacteria are well known for their aggregation ability. However, very little is known about cell surface physicochemical properties of anammox bacteria and thus their aggregation abilities have not been quantitatively evaluated yet. Here, we investigated the aggregation abilities of three different anammox bacterial species: "Candidatus Brocadia sinica", "Ca. Jettenia caeni" and "Ca. Brocadia sapporoensis". Planktonic free-living enrichment cultures of these three anammox species were harvested from the membrane bioreactors (MBRs). The physicochemical properties (e.g., contact angle, zeta potential, and surface thermodynamics) were analyzed for these anammox bacterial species and used in the extended DLVO theory to understand the force-distance relationship. In addition, their extracellular polymeric substances (EPSs) were characterized by X-ray photoelectron spectroscopy and nuclear magnetic resonance. The results revealed that the "Ca. B. sinica" cells have the most hydrophobic surface and less hydrophilic functional groups in EPS than other anammox strains, suggesting better aggregation capability. Furthermore, aggregate formation and anammox bacterial populations were monitored when planktonic free-living cells were cultured in up-flow column reactors under the same conditions. Rapid development of microbial aggregates was observed with the anammox bacterial population shifts to a dominance of "Ca. B. sinica" in all three reactors. The dominance of "Ca. B. sinica" could be explained by its better aggregation ability and the superior growth kinetic properties (higher growth rate and affinity to nitrite). The superior aggregation ability of "Ca. B. sinica" indicates significant advantages (efficient and rapid start-up of anammox reactors due to better biomass retention as granules and consequently stable performance) in wastewater treatment application.
厌氧氨氧化（anammox）细菌以其聚集能力而闻名。然而，人们对 anammox 细菌的细胞表面物理化学特性知之甚少，因此尚未对其聚集能力进行定量评估。在这里，我们研究了三种不同的 anammox 细菌的聚集能力：“Candidatus Brocadia sinica”、“Ca. Jettenia caeni”和“Ca. Brocadia sapporoensis”。从膜生物反应器（MBR）中收获了这些三种 anammox 物种的浮游自由生活富集培养物。分析了这些 anammox 细菌的物理化学特性（例如接触角、动电位和表面热力学），并将其用于扩展的 DLVO 理论，以了解力-距离关系。此外，通过 X 射线光电子能谱和核磁共振对其细胞外聚合物物质（EPS）进行了表征。结果表明，与其他 anammox 菌株相比，“Ca. B. sinica”细胞具有最疏水的表面和较少的亲水性 EPS 官能团，表明其具有更好的聚集能力。此外，在相同条件下，当浮游自由生活细胞在升流式柱反应器中培养时，监测了聚集物的形成和 anammox 细菌的种群变化。在所有三个反应器中，随着 anammox 细菌种群向“Ca. B. sinica”优势种群的转变，微生物聚集物迅速发展。“Ca. B. sinica”的优势地位可以用其更好的聚集能力和优越的生长动力学特性（更高的生长速率和对亚硝酸盐的亲和力）来解释。“Ca. B. sinica”的优越聚集能力表明，在废水处理应用中，由于颗粒状更好的生物量保留和因此稳定的性能，其具有显著的优势（anammox 反应器的高效和快速启动）。
