Analyzing the roles of cyclic dimeric guanosine monophosphate (c-di-GMP) on the formation of autotrophic granules and autotrophic biofilm in integrated fixed-film activated sludge (IFAS) reactor

• Published in: Environmental technology & innovation Vol. 26; p. 102304
• Main Authors: Zhang, Kai, Zhang, Jing, Li, Jun, Zheng, Zhaoming, Sun, Mengxia
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2022
• Subjects: Autotrophic biofilm (AUB); Autotrophic granules (AUGS); Cyclic dimeric guanosine monophosphate (c-di-GMP); Extracellular polymeric substances (EPS); Integrated fixed-film activated sludge (IFAS); Partial nitrification/anammox (PN/A); Autotrophic biofilm (AUB); Integrated fixed-film activated sludge (IFAS); Extracellular polymeric substances (EPS); Autotrophic granules (AUGS); Cyclic dimeric guanosine monophosphate (c-di-GMP); Partial nitrification/anammox (PN/A)
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2022.102304

This study is the first to reveal the important roles of c-di-GMP on the formation of autotrophic granular sludge (AUGS) and autotrophic biofilm (AUB) in integrated fixed-film activated sludge (IFAS) system. The results revealed that the partial nitrification/anammox (PN/A) performance was successfully developed in the IFAS system and high nitrogen removal efficiency was obtained. Notably, it was clearly indicated that the intracellular c-di-GMP content was highly linearly correlated with the concentration of protein (PN) in tightly bound extracellular polymeric substances (TB-EPS) during AUGS formation. It was also found that the c-di-GMP content was highly linearly correlated with the PN concentration during AUB formation, and also had a good linear correlation with the polysaccharide (PS) content in TB-EPS. This proves that intracellular c-di-GMP played a vital role in regulating the TB-EPS secretion, thereby further affecting the aggregation ability of AUGS and AUB. In addition, when the c-di-GMP regulates the content of PN in TB-EPS, the secondary structure of the PN also changes significantly correspondingly, affecting the hydrophobicity of AUGS and AUB. In long-term operation, Candidatus_Kuenenia, Nitrosomonas and Flavobacterium gradually became dominant species, which were considered to favor the formation of AUGS and AUB by promoting the production of c-di-GMP and TB-EPS. [Display omitted] •Autotrophic granules (AUGS) and autotrophic biofilm (AUB) were formed in IFAS system.•During the formation of AUGS, the c-di-GMP was highly linear with PN in TB-EPS.•During the formation of AUB, the c-di-GMP was highly linear with PN and PS in TB-EPS.•The functional bacteria of AUGS and AUB were Candidatus_Kuenenia and Nitrosomonas.•Candidatus_Kuenenia, Nitrosomonas and Flavobacterium participate in c-di-GMP metabolism.