<p>The stable operation of membrane bioreactors (MBRs) strongly depends on the extent of membrane fouling. Phages are gaining recognition as ideal and sustainable biological agents for mitigating membrane fouling, but the limited understanding of phage composition, function profiles, and their relationship with actual membrane fouling behavior greatly constrains engineering applications. This study demonstrated the critical role of phage-bacterium interactions in both the formation and mitigation of fouling in anaerobic membrane bioreactors (AnMBRs). Firstly, phages within the fouling layers exhibited greater diversity than those in sludge. Lytic phages in the fouling layers target ∼42% of the top 100 most abundant species and biofilm-forming bacteria. In addition, adverse conditions caused by high transmembrane pressure (TMP) and the presence of harmful substances in sewage triggered prophage activation; notably, 19.1%–26.3% of contigs in the gel layer contained prophages, a 3.2- to 5.3-fold higher compared to sludge (3.6%–6.1%). These findings underscored the potential role of the phage lysis cycle in alleviating membrane fouling. Phage-encoded auxiliary metabolic genes (AMGs; 138 types in total) related to fouling formation, bacterial integrity, and stress tolerance were identified, potentially enhancing fouling stability. Conversely, phage-encoded AMGs associated with polysaccharide and protein degradation may promoted biofilm breakdown, and the combined lysis cycle further alleviate membrane fouling. Overall, this study revealed, for the first time, the potential role of phages in both the formation and mitigation of membrane fouling in AnMBRs, and provided theoretical support for phage therapy in controlling membrane fouling.</p>

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Exploring the potential positive impact of phage-bacterium interactions on membrane fouling mitigation

  • Bei Zang,
  • Hang Zhou,
  • Huakai Nan,
  • Yu Li,
  • Qian Li,
  • Daisuke Sano,
  • Rong Chen

摘要

The stable operation of membrane bioreactors (MBRs) strongly depends on the extent of membrane fouling. Phages are gaining recognition as ideal and sustainable biological agents for mitigating membrane fouling, but the limited understanding of phage composition, function profiles, and their relationship with actual membrane fouling behavior greatly constrains engineering applications. This study demonstrated the critical role of phage-bacterium interactions in both the formation and mitigation of fouling in anaerobic membrane bioreactors (AnMBRs). Firstly, phages within the fouling layers exhibited greater diversity than those in sludge. Lytic phages in the fouling layers target ∼42% of the top 100 most abundant species and biofilm-forming bacteria. In addition, adverse conditions caused by high transmembrane pressure (TMP) and the presence of harmful substances in sewage triggered prophage activation; notably, 19.1%–26.3% of contigs in the gel layer contained prophages, a 3.2- to 5.3-fold higher compared to sludge (3.6%–6.1%). These findings underscored the potential role of the phage lysis cycle in alleviating membrane fouling. Phage-encoded auxiliary metabolic genes (AMGs; 138 types in total) related to fouling formation, bacterial integrity, and stress tolerance were identified, potentially enhancing fouling stability. Conversely, phage-encoded AMGs associated with polysaccharide and protein degradation may promoted biofilm breakdown, and the combined lysis cycle further alleviate membrane fouling. Overall, this study revealed, for the first time, the potential role of phages in both the formation and mitigation of membrane fouling in AnMBRs, and provided theoretical support for phage therapy in controlling membrane fouling.