好氧颗粒污泥耐受PFOS的结构稳定性及微生物响应

以好氧颗粒污泥为接种污泥,通过全氟辛烷磺酸(PFOS)长期驯化实现耐PFOS颗粒的培养,考察不同驯化时期的污泥基本特性,并结合微生物群落演替过程、微生物表型分布以及功能途径的变化情况,以揭示其耐受机制。结果表明,好氧颗粒污泥经历解体、再形成和成熟3个阶段后可在PFOS暴露下稳定维持。驯化成熟后的好氧颗粒污泥表面丝状菌减少,并且被大量胞外聚合物(EPS)所包裹,结构更加致密。驯化期间颗粒污泥中存在大量抗性细菌以及维持颗粒稳定相关细菌,主要包括unclassified_f__Comamonadaceae、Defluviicoccus、Dongia、Rhodoplanes、Flavobacterium、Thauera、Azospira、Candidatus_Competibacter、Azoarcus和norank_f__A4b,且部分菌属间存在显著的正相关性。群体感应途径和细菌趋化途径相关基因丰度在解体期上调,在颗粒形成和成熟期恢复至初始水平,说明细菌的群体感应效应和趋化性能够在颗粒应激过程中起重要作用。因此,好氧颗粒污泥可以通过特定菌群积极响应、促进细菌趋化作用和群体感应作用、提高EPS分泌量、增强系统抗氧化胁迫能力等多种方式耐受PFOS。采用菌胶团型好氧颗粒污泥以及向好氧颗粒污泥系统中投加上述菌剂或添加信号分子有利于处理含PFOS废水。

Structural stability and microbial response mechanism of aerobic granular sludge exposed to perfluorooctane sulfonate

The aerobic granular sludge that can tolerate perfluorooctane sulfonate (PFOS) was successfully cultivated in a lab-scale sequence batch reactor system. The tolerance mechanism of aerobic granular sludge to PFOS was discovered by examining the sludge characteristics, microbial communities, microbial phenotypes, and functional pathways in various domestication periods. In the presence of PFOS, the granular sludge maintained good stability through the disintegration, formation and maturation phases. PFOS reduced the filamentous bacteria, but promoted EPS secretion. The aforementioned phenomena were beneficial for the formation of compact structure of granules. During the whole domestication stage, a significant number of resistant bacteria and bacteria associated with the maintenance of granule stability emerged in granules, mainly including unclassified_f__ Comamonadaceae, Defluviicoccus, Dongia, Rhodoplanes, Flavobacterium, Thauera, Azospira, Azoarcus, Candidatus_ Competibacter, and norank_f__A4b, and there were significant positive correlations among some genera. In addition, the abundance of genes related to the quorum sensing pathway and the bacterial chemotaxis pathway up-regulated in the disintegration period, but returned to the initial level in the formation and maturation periods. It suggested that the bacterial quorum sensing system and chemotactic ability could play important roles in the process of granular stress. Therefore, aerobic granular sludge could tolerate PFOS in various ways such as positive response of specific bacterial communities, promotion of bacterial chemotaxis and quorum sensing, enhancement of EPS secretion, and enhancement of antioxidant stress capacity of the system. The application of EPS-based aerobic granular sludge, microbial agents, and signal molecules was conducive to the treatment of wastewater containing PFOS.