Journal Article

Comparative genomics of two ‘Candidatus Accumulibacter’ clades performing biological phosphorus removal

He, Shaomei, Malfatti, Stephanie, Tringe, Susannah G, McMahon, Katherine D, del Rio, Tijana Glavina, Hugenholtz, Philip, Flowers, Jason J

2013

Overview

Members of the genus Candidatus Accumulibacter are important in many wastewater treatment systems performing enhanced biological phosphorus removal (EBPR). The Accumulibacter lineage can be subdivided phylogenetically into multiple clades, and previous work showed that these clades are ecologically distinct. The complete genome of Candidatus Accumulibacter phosphatis strain UW-1, a member of Clade IIA, was previously sequenced. Here, we report a draft genome sequence of Candidatus Accumulibacter spp. strain UW-2, a member of Clade IA, assembled following shotgun metagenomic sequencing of laboratory-scale bioreactor sludge. We estimate the genome to be 80–90% complete. Although the two clades share 16S rRNA sequence identity of >98.0%, we observed a remarkable lack of synteny between the two genomes. We identified 2317 genes shared between the two genomes, with an average nucleotide identity (ANI) of 78.3%, and accounting for 49% of genes in the UW-1 genome. Unlike UW-1, the UW-2 genome seemed to lack genes for nitrogen fixation and carbon fixation. Despite these differences, metabolic genes essential for denitrification and EBPR, including carbon storage polymer and polyphosphate metabolism, were conserved in both genomes. The ANI from genes associated with EBPR was statistically higher than that from genes not associated with EBPR, indicating a high selective pressure in EBPR systems. Further, we identified genomic islands of foreign origins including a near-complete lysogenic phage in the Clade IA genome. Interestingly, Clade IA appeared to be more phage susceptible based on it containing only a single Clustered Regularly Interspaced Short Palindromic Repeats locus as compared with the two found in Clade IIA. Overall, the comparative analysis provided a genetic basis to understand physiological differences and ecological niches of Accumulibacter populations, and highlights the importance of diversity in maintaining system functional resilience.

• Publisher: Nature Publishing Group UK,Oxford University Press,Nature Publishing Group
• Subject: 631/208/212/2306 / 631/208/212/748 / 631/326/2565/855 / Biodiversity / Biomedical and Life Sciences / Bioreactors / Candidatus Accumulibacter / Carbon fixation / Carbon sequestration / Clustered Regularly Interspaced Short Palindromic Repeats / Comparative analysis / CRISPR / Denitrification / DNA, Bacterial - genetics / Ecological niches / Ecology / Evolutionary Biology / Genes / Genetic analysis / Genome, Bacterial / Genomes / Genomic islands / Genomics / Islands / Life Sciences / Metagenomics / Microbial Ecology / Microbial Genetics and Genomics / Microbiology / Niches / Nitrogen fixation / Nitrogenation / Nucleotide sequence / Nucleotides / Original / original-article / Phages / Phosphorus / Phosphorus - metabolism / Phosphorus removal / Phylogeny / Physiology / Polymers / RNA, Ribosomal, 16S - genetics / rRNA 16S / Sequence Homology, Nucleic Acid / Sewage - microbiology / Sludge / Synteny / Waste Water - microbiology / Wastewater treatment