Phylogenetic analysis reveals diversity in glycan biosynthesis in “Candidatus Accumulibacter”

TL;DR

This paper explores the diversity of glycan biosynthesis in the genus 'Candidatus Accumulibacter' using genomic data.

Contribution

The study identifies a conserved core and variable accessory set of nucleotide-sugars in glycan biosynthesis within the genus.

Findings

A conserved core group of 9 nucleotide-sugars was found in most 'Ca. Accumulibacter' MAGs.

An accessory set of 12 nucleotide-sugars showed irregular phylogenetic distribution and divergent evolutionary histories.

The accessory nucleotide-sugars are enriched in rare sugars and suggest horizontal gene transfer influences.

Abstract

Although biofilms are widespread in nature, the ecological roles and compositional diversity of the extracellular polymeric substances (EPS) forming these structures remain poorly understood. Here, we apply a bottom-up genomic approach by investigating the biosynthetic potential for glycan precursors in the genus “Candidatus Accumulibacter”, with a focus on assessing the intra-genus variability. Within a curated set of 61 “Ca. Accumulibacter” MAGs, our analysis revealed a dichotomy in glycan precursors between a conserved core group of 9 nucleotide-sugars and a variable accessory set of 12 nucleotide-sugars, out of 50 nucleotide-sugars tested. The core nucleotide-sugars in “Ca. Accumulibacter” are related to nucleotide-sugars also found to be widely distributed across the tree of life, whereas the accessory set is enriched in rare nucleotide-sugars. The accessory nucleotide-sugars show an irregular distribution across “Ca. Accumulibacter” phylogeny, and divergent evolutionary histories. This highlights the possibility that distinct evolutionary pressures act on different parts of the EPS-formation metabolism, leading to genotypic diversification driven by complex biological phenomena such as horizontal gene transfer that support the observed divergent evolutionary histories.

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