Genome-resolved taxonomy, global distribution, and EPS potential of Zoogloea, the canonical floc-former in wastewater treatment systems.

A genome-resolved analysis of activated sludge genomes identified 47 phylogenetically defined Zoogloea genomes globally, clarifying its taxonomy and enabling mapping of an EPS-linked floc-forming gene cluster.

• Why it matters: Stable floc formation in activated sludge depends on extracellular polymeric substances, but Zoogloea’s misclassification has obscured which lineages produce the polysaccharides and where they occur.
• What they did: Using the MiDAS global genome catalog (>22,000 genomes), the study screened for a recently identified Zoogloea-associated floc-forming polysaccharide biosynthesis gene cluster and assessed its phylogenetic spread and conservation.
• The result: The gene cluster was found across multiple Burkholderiales genera—including Zoogloea, Thauera, Azoarcus, and Ca. Accumulibacter—and was broadly conserved with minor synteny and gene-composition variation, alongside co-occurring floc-regulating genes.

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