Draft Genome Sequences of Achromobacter piechaudii GCS2, Agrobacterium sp. Strain SUL3, Microbacterium sp. Strain GCS4, Shinella sp. Strain GWS1, and Shinella sp. Strain SUS2 Isolated from Consortium with the Hydrocarbon-Producing Alga Botryococcus braunii.

A variety of bacteria associate with the hydrocarbon-producing microalga Botryococcus braunii, some of which may influence its growth. We report here the genome sequences for Achromobacter piechaudii GCS2, Agrobacterium sp. strain SUL3, Microbacterium sp. strain GCS4, and Shinella sp. strains GWS1 and SUS2, isolated from a laboratory culture of B. braunii, race B, strain Guadeloupe.

GENOME ANNOUNCEMENT

Botryococcus braunii is a green microalga that is able to produce and accumulate high levels of hydrocarbons (up to 60% of its dry weight, depending on the strain), which can be converted into liquid fuels (1, 2). Strains of B. braunii are typically not axenic but consist of a single algal strain accompanied by a variety of microorganisms associated as both a biofilm and planktonic population in the water column, which may greatly influence B. braunii growth and hydrocarbon production (3–6).

Five bacterial strains (GCS2, SUL3, GCS4, GWS1, and SUS2) were isolated from a long-term laboratory culture of B. braunii strain Guadeloupe (race B) (7), and the colonies were grown on LB plates. Genomic DNA fragmented by sonication was concentrated and purified using a QIAquick column (Qiagen), and genomic libraries were prepared using the NEBNext DNA Library Prep Master Mix Set for Illumina (New England BioLabs). One hundred fifty-base pair paired-end sequencing, with a custom bar code, was carried out on an Illumina MiSeq, and de novo assembly of the sequence data was carried out using SPAdes version 3.5.0 (8). The number of contigs, coverage, N50, and total sequence length were, respectively, 20, 41×, 626,645, and 6,180,134 bp for Achromobacter piechaudii GCS2; 72, 52×, 358,737, and 6,013,863 bp for Agrobacterium sp. strain SUL3; 7, 73×, 944,354, and 3,652,908 bp for Microbacterium sp. strain GCS4; 141, 44×, 176,944, and 6,989,725 bp for Shinella sp. strain GWS1; and 112, 32×, 264,748, and 7,005,767 bp for Shinella sp. strain SUS2. The genomes were annotated using the NCBI Prokaryotic Genome Annotation Pipeline (PGAP), which predicted 5,433, 5,585, 3,325, 6,636, and 6,361 coding sequences (CDSs), respectively, for the five strains. The G+C contents varied between 59.2% (Agrobacterium sp. SUL3) and 69.5% (Microbacterium sp. GCS4). The 16S rRNA gene sequences were extracted using RNAmmer (9).

Phylogenetic analysis of 16S rRNA gene sequence, atpD, recA, rpoB, and tyrB suggested that GCS2 belongs to the species A. piechaudii; its genome shares 98.4% average nucleotide identity (ANI) with that of A. piechaudii strain ATCC 43553. Phylogenetic analysis of 16S rRNA gene sequence, gyrB, ppk, recA, and rpoB suggested that GCS4 belongs to the genus Microbacterium. Phylogenetic analysis of 16S rRNA gene sequence, atpD, and recA suggested that GWS1 and SUS2 both belong to the genus Shinella, and SUL3 belongs to the genus Agrobacterium.

None of these five bacteria were previously reported in association with B. braunii, except for Shinella sp. GWS1 and SUS2, which, on the basis of partial 16S rRNA gene sequence, are indistinguishable from a biofilm isolate found to enhance the growth of a laboratory-maintained monoculture of B. braunii (4) (reported as Rhizobium sp. M14). Many species of algae are auxotrophic for vitamin B1 (thiamine), vitamin B7 (biotin), and vitamin B12 (cobalamin) (10). We identified genes encoding pathways for thiamine synthesis in all five genomes; cobalamin is likely to be synthesized by Agrobacterium sp. SUL3 and Shinella spp. GWS1 and SUS2, while biotin is likely to be synthesized by A. piechaudii GCS2 and Agrobacterium sp. SUL3. No evidence of nitrogen fixation genes was found in any of the bacterial genomes, based on tBLASTn and BLASTn searches.

Nucleotide sequence accession numbers.

These genome sequences have been deposited at GenBank under the following accession numbers: A. piechaudii GCS2, LGYD00000000; Agrobacterium sp. SUL3, LGZB00000000; Microbacterium sp. GCS4, LGYE00000000; Shinella sp. GWS1, LGYF00000000; and Shinella sp. SUS2, LGYG00000000. The versions described in this paper are the first versions: LGYD01000000, LGZB01000000, LGYE01000000, LGYF01000000, and LGYG01000000.