# 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.

## Key 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.