Identification and degradation of structural extracellular polymeric substances in waste activated sludge via a polygalacturonate-degrading consortium

Zhi-Yi Hu; Yi-Peng Lin; Qing-Ting Wang; Yi-Xin Zhang; Jie Tang; Si-Di Hong; Kun Dai; Shuai Wang; Yong-Ze Lu; Mark C M van Loosdrecht; Jianrong Wu; Raymond Jianxiong Zeng; Fang Zhang

doi:10.1016/j.watres.2023.119800

Identification and degradation of structural extracellular polymeric substances in waste activated sludge via a polygalacturonate-degrading consortium

Water Res. 2023 Apr 15:233:119800. doi: 10.1016/j.watres.2023.119800. Epub 2023 Feb 24.

Authors

Affiliations

¹ Engineering Research Center of Soil Remediation of Fujian Province University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
² School of Energy and Environment, Southeast University, Nanjing 210096, China.
³ Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the Netherlands.
⁴ Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
⁵ Engineering Research Center of Soil Remediation of Fujian Province University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Electronic address: rzeng@ustc.edu.cn.
⁶ Engineering Research Center of Soil Remediation of Fujian Province University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Electronic address: zhfang@mail.ustc.edu.cn.

PMID: 36868117
DOI: 10.1016/j.watres.2023.119800

Abstract

By maintaining the cell integrity of waste activated sludge (WAS), structural extracellular polymeric substances (St-EPS) resist WAS anaerobic fermentation. This study investigates the occurrence of polygalacturonate in WAS St-EPS by combining chemical and metagenomic analyses that identify ∼22% of the bacteria, including Ferruginibacter and Zoogloea, that are associated with polygalacturonate production using the key enzyme EC 5.1.3.6. A highly active polygalacturonate-degrading consortium (GDC) was enriched and the potential of this GDC for degrading St-EPS and promoting methane production from WAS was investigated. The percentage of St-EPS degradation increased from 47.6% to 85.2% after inoculation with the GDC. Methane production was also increased by up to 2.3 times over a control group, with WAS destruction increasing from 11.5% to 28.4%. Zeta potential and rheological behavior confirmed the positive effect which GDC has on WAS fermentation. The major genus in the GDC was identified as Clostridium (17.1%). Extracellular pectate lyases (EC 4.2.2.2 and 4.2.2.9), excluding polygalacturonase (EC 3.2.1.15), were observed in the metagenome of the GDC and most likely play a core role in St-EPS hydrolysis. Dosing with GDC provides a good biological method for St-EPS degradation and thereby enhances the conversion of WAS to methane.

Keywords: Anaerobic digestion; Clostridium; Pectate lyases; Polygalacturonate-degrading consortium; Structural extracellular polymeric substances; Waste activated sludge.

MeSH terms

Anaerobiosis
Extracellular Polymeric Substance Matrix
Methane
Sewage* / chemistry
Waste Disposal, Fluid* / methods

Substances

Sewage
polygalacturonic acid
Methane