As the closest living relatives of animals, choanoflagellates offer insights into the ancestry of animal cell physiology. Here, we report the isolation and characterization of a colonial choanoflagellate from Mono Lake, California. The choanoflagellate forms large spherical colonies that are an order of magnitude larger than those formed by the closely related choanoflagellate Salpingoeca rosetta. In cultures maintained in the laboratory, the lumen of the spherical colony is filled with a branched network of extracellular matrix and colonized by bacteria, including diverse Gammaproteobacteria and Alphaproteobacteria. We propose to erect Barroeca monosierra gen. nov., sp. nov. Hake, Burkhardt, Richter, and King to accommodate this extremophile choanoflagellate. The physical association between bacteria and B. monosierra in culture presents a new experimental model for investigating interactions among bacteria and eukaryotes. Future work will investigate the nature of these interactions in wild populations and the mechanisms underpinning the colonization of B. monosierra spheres by bacteria.
This dataset contains the genome sequence of B. monosierra (NKKH001C_Barroeca_monosierra.fa.gz), as well as 24 associated bacterial genome sequences (bacterial_genomes.zip).

The two ZIP archives whose names begin with "tree" contain all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA formatpolyA_removed: polyA tails removed by trimest (for protein coding genes only)aligned: sequence alignments by FSAtrimmed: trimmed alignments by trimAlRAxML: input, run parameters and output of RAxML maximum likelihood tree reconstructionMrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction
The file Figure_2E.tree contains the tree from Figure 2E in Newick format.

As the closest living relatives of animals, choanoflagellates offer insights into the ancestry of animal cell physiology. Here, we report the isolation and characterization of a colonial choanoflagellate from Mono Lake, California. The choanoflagellate forms large spherical colonies that are an order of magnitude larger than those formed by the closely related choanoflagellate Salpingoeca rosetta. In cultures maintained in the laboratory, the lumen of the spherical colony is filled with a branched network of extracellular matrix and colonized by bacteria, including diverse Gammaproteobacteria and Alphaproteobacteria. We propose to erect Barroeca monosierra gen. nov., sp. nov. Hake, Burkhardt, Richter, and King to accommodate this extremophile choanoflagellate. The physical association between bacteria and B. monosierra in culture presents a new experimental model for investigating interactions among bacteria and eukaryotes. Future work will investigate the nature of these interactions in wild populations and the mechanisms underpinning the colonization of B. monosierra spheres by bacteria.
This dataset contains the genome sequence of B. monosierra (NKKH001C_Barroeca_monosierra.fa.gz), as well as 24 associated bacterial genome sequences (bacterial_genomes.zip).

The two ZIP archives whose names begin with "tree" contain all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA formatpolyA_removed: polyA tails removed by trimest (for protein coding genes only)aligned: sequence alignments by FSAtrimmed: trimmed alignments by trimAlRAxML: input, run parameters and output of RAxML maximum likelihood tree reconstructionMrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction
The file Figure_2E.tree contains the tree from Figure 2E in Newick format.

Choanoflagellates offer key insights into bacterial influences on the origin and early evolution of animals. Here we report the isolation and characterization of a new colonial choanoflagellate species, Barroeca monosierra, that, unlike previously characterized species, harbors a stable microbiome. B. monosierra was isolated from Mono Lake, California and forms large spherical colonies that are more than an order of magnitude larger than those formed by the closely related Salpingoeca rosetta. By designing fluorescence in situ hybridization probes from metagenomic sequences, we found that B. monosierra colonies are colonized by members of the halotolerant and closely related Saccharospirillaceae and Oceanospirillaceae, as well as purple sulfur bacteria (Ectothiorhodospiraceae) and non-sulfur Rhodobacteraceae. This relatively simple microbiome in a close relative of animals presents a new experimental model for investigating the evolution of stable interactions among eukaryotes and bacteria.
This dataset contains the genome sequence of B. monosierra, as well as 24 associated bacterial genome sequences.

The two ZIP archives whose names begin with "tree" contain all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA format polyA_removed: polyA tails removed by trimest (for protein coding genes only) aligned: sequence alignments by FSA trimmed: trimmed alignments by trimAl RAxML: input, run parameters and output of RAxML maximum likelihood tree reconstruction MrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction
The file Figure_2E.tree contains the tree from Figure 2E in Newick format.

As the closest living relatives of animals, choanoflagellates may offer insights into the ancestry of interactions among animals and bacteria. Here we report the isolation and characterization of a colonial choanoflagellate species, Barroeca monosierra harbors a bacterial community in its lumen. B. monosierra was isolated from Mono Lake, California and forms large spherical colonies that are an order of magnitude larger than those formed by the closely related choanoflagellate Salpingoeca rosetta. The rosettes, which can develop from single cells, are filled with a branched network of undefined extracellular matrix. We found that lab-reared B. monosierra colonies are colonized by members of the halotolerant Saccharospirillaceae and Oceanospirillaceae, as well as purple sulfur bacteria (Ectothiorhodospiraceae) and non-sulfur Rhodobacteraceae. This relatively simple bacterial community in a close relative of animals presents a new experimental model for investigating the evolution of stable interactions among eukaryotes and bacteria.
This dataset contains the genome sequence of B. monosierra, as well as 24 associated bacterial genome sequences.

The two ZIP archives whose names begin with "tree" contain all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA formatpolyA_removed: polyA tails removed by trimest (for protein coding genes only)aligned: sequence alignments by FSAtrimmed: trimmed alignments by trimAlRAxML: input, run parameters and output of RAxML maximum likelihood tree reconstructionMrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction
The file Figure_2E.tree contains the tree from Figure 2E in Newick format.

Choanoflagellates offer key insights into bacterial influences on the origin and early evolution of animals. Here we report the isolation and characterization of a new colonial choanoflagellate species, Barroeca monosierra, that, unlike previously characterized species, harbors a stable microbiome. B. monosierra was isolated from Mono Lake, California and forms large spherical colonies that are more than an order of magnitude larger than those formed by the closely related Salpingoeca rosetta. By designing fluorescence in situ hybridization probes from metagenomic sequences, we found that B. monosierra colonies are colonized by members of the halotolerant and closely related Saccharospirillaceae and Oceanospirillaceae, as well as purple sulfur bacteria (Ectothiorhodospiraceae) and non-sulfur Rhodobacteraceae. This relatively simple microbiome in a close relative of animals presents a new experimental model for investigating the evolution of stable interactions among eukaryotes and bacteria.
This dataset contains all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA formatpolyA_removed: polyA tails removed by trimest (for protein coding genes only)aligned: sequence alignments by FSAtrimmed: trimmed alignments by trimAlRAxML: input, run parameters and output of RAxML maximum likelihood tree reconstructionMrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction

Choanoflagellates offer key insights into bacterial influences on the origin and early evolution of animals. Here we report the isolation and characterization of a new colonial choanoflagellate species, Barroeca monosierra, that, unlike previously characterized species, harbors a stable microbiome. B. monosierra was isolated from Mono Lake, California and forms large spherical colonies that are more than an order of magnitude larger than those formed by the closely related Salpingoeca rosetta. By designing fluorescence in situ hybridization probes from metagenomic sequences, we found that B. monosierra colonies are colonized by members of the halotolerant and closely related Saccharospirillaceae and Oceanospirillaceae, as well as purple sulfur bacteria (Ectothiorhodospiraceae) and non-sulfur Rhodobacteraceae. This relatively simple microbiome in a close relative of animals presents a new experimental model for investigating the evolution of stable interactions among eukaryotes and bacteria.
This dataset contains the genome sequence of B. monosierra, as well as 24 associated bacterial genome sequences.

The two ZIP archives whose names begin with "tree" contain all relevant data from the phylogenetic trees presented in Figure 1C and Figure S1. Each archive contains the following subdirectories:
input: input sequences in FASTA formatpolyA_removed: polyA tails removed by trimest (for protein coding genes only)aligned: sequence alignments by FSAtrimmed: trimmed alignments by trimAlRAxML: input, run parameters and output of RAxML maximum likelihood tree reconstructionMrBayes: input, run parameters and output of MrBayes Bayesian tree reconstruction