Identification of Extracellular Key Enzyme and Intracellular Metabolic Pathway in Alginate-Degrading Consortia via an Integrated Metaproteomic/Metagenomic Analysis

Journal article (2021)

Authors

Zi Qian Geng Fujian Agriculture and Forestry University, Fuzhou, Fujian
Ding Kang Qian Fujian Agriculture and Forestry University, Fuzhou, Fujian
Zhi Yi Hu Fujian Agriculture and Forestry University, Fuzhou, Fujian
S.W. WANG Fujian Agriculture and Forestry University, Fuzhou, Fujian
Yang Yan Fujian Agriculture and Forestry University, Fuzhou, Fujian
Mark C.M. van Loosdrecht BT/Environmental Biotechnology - AS
Raymond Jianxiong Zeng Fujian Agriculture and Forestry University, Fuzhou, Fujian
Fang Zhang Fujian Agriculture and Forestry University, Fuzhou, Fujian
Research Group
BT/Environmental Biotechnology (AS) (TU Delft)
Bacteroides Alginate-degrading consortia DDG and DGH Extracellular alginate lyase (EC 4.2.2.3) New Entner-Doudoroff pathway Two chemostats in series
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Published Date

2021

Language

English

Reuse Rights

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Faculty

Applied Sciences

Department

BT/Biotechnologie

Research Group

BT/Environmental Biotechnology

Abstract

Uronic acid in extracellular polymeric substances is a primary but often ignored factor related to the difficult hydrolysis of waste-activated sludge (WAS), with alginate as a typical polymer. Previously, we enriched alginate-degrading consortia (ADC) in batch reactors that can enhance methane production from WAS, but the enzymes and metabolic pathway are not well documented. In this work, two chemostats in series were operated to enrich ADC, in which 10 g/L alginate was wholly consumed. Based on it, the extracellular alginate lyase (∼130 kD, EC 4.2.2.3) in the cultures was identified by metaproteomic analysis. This enzyme offers a high specificity to convert alginate to disaccharides over other mentioned hydrolases. Genus Bacteroides (>60%) was revealed as the key bacterium for alginate conversion. A new Entner-Doudoroff pathway of alginate via 5-dehydro-4-deoxy-d-glucuronate (DDG) and 3-deoxy-d-glycerol-2,5-hexdiulosonate (DGH) as the intermediates to 2-keto-3-deoxy-gluconate (KDG) was constructed based on the metagenomic and metaproteomic analysis. In summary, this work documented the core enzymes and metabolic pathway for alginate degradation, which provides a good paradigm when analyzing the degrading mechanism of unacquainted substrates. The outcome will further contribute to the application of Bacteroides-dominated ADC on WAS methanogenesis in the future.