Draft Genome Sequences of Four Microcystis aeruginosa Strains (NIES-3787, NIES-3804, NIES-3806, and NIES-3807) Isolated from Lake Kasumigaura, Japan

Microcystis aeruginosa is a bloom-forming cyanobacterium found in freshwater environments. The draft genomes of the M. aeruginosa strains NIES-3787, NIES-3804, NIES-3806, and NIES-3807, which were isolated from Lake Kasumigaura, Japan, were sequenced. The genome sizes of NIES-3787, NIES-3804, NIES-3806, and NIES-3807 were 4,524,637, 4,522,701, 4,370,004, and 4,378,226 bp, respectively.

C yanobacterial blooms occur widely in freshwater environments worldwide (1).
Microcystis aeruginosa is the most well-known bloom-forming cyanobacterium, and it is distributed in eutrophic freshwater environments. The most serious problem associated with this species is the production of hepatotoxic cyanotoxins called microcystins (2,3). M. aeruginosa isolates are genetically divided into at least 12 phylogenetic groups (groups A to K and X) based on multilocus phylogenetic analyses (2,3). The strains in groups A and X, as well as some B strains, produce microcystins (3,4). In the current study, we sequenced M. aeruginosa strains NIES-3787, NIES-3804, NIES-3806, and NIES-3807, isolated from Lake Kasumigaura, Japan.
Axenic cultures of M. aeruginosa NIES-3787, NIES-3804, NIES-3806, and NIES-3807 were obtained from the microbial culture collection of the National Institute for Environmental Studies (https://mcc.nies.go.jp/index.html). These strains were established by using a micropipette under an inverted microscope. The strains were cultured in 10 ml of Microcystis aeruginosa medium at 22°C under light at 25 mol photons m Ϫ2 s Ϫ1 with a 12:12-h light/dark cycle. Genomic DNA was extracted from 10-ml cultures of these strains using Agencourt Chloropure (Beckman Coulter) following the manufacturer's protocol. The resultant DNAs were fragmented to approximately 550 bp using an M220 ultrasonicator (Covaris). Genomic libraries of paired-end reads were constructed using a NEBNext Ultra II DNA library prep kit for Illumina (New England Biolabs). Next-generation sequencing was performed with the MiSeq platform (Illumina) using a 500-cycle MiSeq reagent kit version 2. The resultant paired-end reads for NIES-3787, NIES-3804, NIES-3806, and NIES-3807 were 151,461,029 bp, 643,439,906 bp, 395,828,445 bp, and 197,435,680 bp, respectively. The raw reads were trimmed using Trimmomatic version 0.38 (5), and then de novo assembly was performed using SPAdes version 3.11.1 (6) in Shovill version 1.0.4 (https://github.com/tseemann/shovill). Next, the assembled scaffolds were polished using Pilon version 1.22 (7). After the removal of short reads (Ͻ200 bp), functional annotation was performed using the DFAST legacy server (8) with CyanoBase (9) as a database. We used CheckM version 1.0.11 to estimate genome completeness (10). Default parameters were used for all software. Group identification analysis of each strain was carried out based on ftsZ, one of seven multilocus sequence typing loci (2, 3).

ACKNOWLEDGMENTS
We thank Nobuyoshi Nakajima (National Institute for Environmental Studies) for genome sequencing.
This work was partially supported by the National BioResource Project for Algae under grant number 17km0210116j0001, which was funded by the Japan Agency for Medical Research and Development (AMED).