Cardona Laëtitia, Saini Jaspreet Singh, Rodilla Ramírez Pilar Natalia, Adler Aline, Holliger Christof
Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Appl Environ Microbiol. 2025 Apr 23;91(4):e0176924. doi: 10.1128/aem.01769-24. Epub 2025 Mar 31.
Aerobic granular sludge is a biological wastewater treatment process in which a microbial community forms a granular biofilm. The role of Accumulibacter in the production of a biofilm matrix composed of extracellular polymeric substances was studied in a sequencing batch reactor enriched with polyphosphate-accumulating organisms. The metabolisms of the microbial populations were investigated using metatranscriptomics analysis. Finally, the effect of decreasing the influent phosphate concentration on the granule stability and microbial activity was investigated. A few weeks after the reactor start-up, the microbial community was dominated by with up to nine species active in parallel. However, the most active species differed according to sampling time. Decreasing drastically the influent phosphate concentration led to a dominance of the glycogen-accumulating organism , with some species still abundant. metatranscriptomics analysis indicated a high diversity of potential extracellular substances produced mainly by , , Contendobacter, and . Moreover, the results suggest that , and recycle the neuraminic acids produced by . Changes in the microbial community did not cause the granules to disintegrate, indicating that a -dominated community can maintain stable granules.IMPORTANCEOne of the main advantages of the aerobic granular sludge wastewater treatment process is the higher settling velocities compared to the conventional activated sludge-based process. In aerobic granular sludge, the biomass is concentrated into a biofilm matrix composed of biopolymers, providing micro-niches to different types of microbial populations. We demonstrate with the help of metatranscriptomics analysis that the formation of granules is a highly dynamic microbial process, even when enriching for a microbial guild, such as phosphate-accumulating organisms. Often underestimated, the flanking community of the main phosphate-accumulating organisms population enriched in the reactor is nonetheless active and transcribing genes related to different extracellular polymeric substance pathways. The multiplicity of the extracellular polymeric substances produced probably helped the matrix to remain stable, thanks to their specific properties. Moreover, the results suggest microbial interactions in extracellular polymeric substance recycling between different microbial populations that can be helpful to prevent a disruption of the granules while stressing out the microbial community.
好氧颗粒污泥是一种生物废水处理工艺，其中微生物群落形成颗粒状生物膜。在一个富集聚磷菌的序批式反应器中，研究了聚磷菌在由胞外聚合物组成的生物膜基质产生过程中的作用。使用宏转录组学分析研究了微生物种群的代谢。最后，研究了降低进水磷酸盐浓度对颗粒稳定性和微生物活性的影响。反应器启动几周后，微生物群落以多达9种并行活跃的物种为主导。然而，最活跃的物种因采样时间而异。大幅降低进水磷酸盐浓度导致糖原积累菌占主导地位，一些其他物种仍然丰富。宏转录组学分析表明，主要由嗜甲基菌属、厌氧绳菌属、争养杆菌属和其他菌属产生的潜在胞外物质具有高度多样性。此外，结果表明，嗜甲基菌属、厌氧绳菌属和争养杆菌属回收了嗜甲基菌属产生的神经氨酸。微生物群落的变化并未导致颗粒解体，这表明以嗜甲基菌属为主导的群落可以维持颗粒的稳定性。
重要性
好氧颗粒污泥废水处理工艺的主要优点之一是与传统的活性污泥法相比，沉降速度更快。在好氧颗粒污泥中，生物质浓缩成由生物聚合物组成的生物膜基质，为不同类型的微生物种群提供微生境。我们借助宏转录组学分析表明，颗粒的形成是一个高度动态的微生物过程，即使在富集微生物群落（如聚磷菌）时也是如此。尽管反应器中富集的主要聚磷菌种群的侧翼群落常常被低估，但它仍然活跃，并转录与不同胞外聚合物途径相关的基因。所产生的胞外聚合物的多样性可能有助于基质保持稳定，这得益于它们的特殊性质。此外，结果表明不同微生物种群之间在胞外聚合物循环中的微生物相互作用有助于在使微生物群落受到压力时防止颗粒破裂。
