Linking Exoproteome Function and Structure to Anammox Biofilm Development

Abstract

Extracellular proteins are of paramount importance in the cell−cell interactions of anammox biofilms. However, the inherent aggregation mechanisms of anammox have largely remained elusive. Herein, using a quartz sand extraction protocol and follow-up iTRAQ-based quantitative proteomics, we identified 367 extracellular proteins from initial colonizers, mature biofilm, and detached biofilm. The extracellular proteins were mainly membrane-associated. Most of the recovered proteins (226, 72.5%) originated from the phylum Planctomycetes. In summary, 215 and 190 of the 367 proteins recovered were up-and/ or downregulated at least 1.2-fold during the biofilm formation and detachment periods, respectively. These differentially expressed proteins were dominantly involved in metal ion binding, which was regarded as strong evidence for their abilities to enhance ionic bridges in extracellular polymeric substances (EPS). Scanning electron microscopy−energy-dispersive X-ray spectroscopy (SEM-EDX) analysis of the biofilms further showed substantial levels of calcium and iron minerals. Critically, representative Sec-dependent secretory proteins affiliated with coccoid Planctomycetes, rod-shaped Proteobacteria, and filamentous Chloroflexi (11, 4, and 2 with differential expression, respectively) were found to have typical and abundant inner βsheet structures, wherein hydrophobic moieties can promote anammox aggregation. Overall, these findings highlight links between differentially expressed protein functions and morphologic traits of anammox consortia during biofilm development.

New Insight Into the Interspecies Shift of Anammox Bacteria Ca. “Brocadia” and Ca. “Jettenia” in Reactors Fed With Formate and Folate

“…"Kuenenia, " and Ca. "Scalindua" (Chen et al, 2019). Increased cell aggregation due to increased synthesis of EPS matrix in response to unfavorable environmental conditions was shown for representatives of the species Ca.…”

“…"Jettenia" to excessively produce extracellular polymeric substances (EPS) could play a key role both in their adhesion to glass and in protection from the toxic effects of DO. Aggregation and adhesion of anammox bacteria occur due to protein-rich EPS (Hou et al, 2015;Chen et al, 2019;Peeters and van Niftrik, 2019). Members of the genus Ca.…”

Surface Characteristics Together With Environmental Conditions Shape Marine Biofilm Dynamics in Coastal NW Mediterranean Locations

“…Planctomycetes are poorly studied "maverick" bacteria (Wiegand et al, 2018), highly represented in activated sludge and among algal surface associated community. Functions like metal binding extrapolymeric proteins or stress response could explain the success of this taxa among the biofilm community (Bondoso et al, 2017;Chen et al, 2019).…”

Recovery of nitrogen removal by N2H4 after nitrite inhibited anammox reaction

“…And this process is different from nitrification and denitrification (Azhdarpoor et al, 2018;Azhdarpoor et al, 2015). Compared with the traditional nitrogen removal process, the anammox process has the advantages of a high nitrogen removal efficiency, eliminating the need for additional organic carbon sources, low residual sludge outputs, and low operating costs (Chen et al, 2019;Kuenen, 2008;Lackner et al, 2014). Anammox technology has been applied in many fields for ammonia nitrogen wastewater treatment, such as livestock and poultry farming with wastewater (Wang X. et al, 2019), landfill leachate (Wang Z. et al, 2016), and monosodium glutamate production wastewater (Shen et al, 2012), and has become a research hotspot in the field of ammonia nitrogen wastewater treatment in China (Wen et al, 2020).…”