title: Whole genome assembly of a natto production strain Bacillus subtilis natto from very short read data.
abstract: BACKGROUND
  Bacillus subtilis natto is closely related to the laboratory standard strain B. subtilis Marburg 168, and functions as a starter for the production of the traditional Japanese food "natto" made from soybeans. Although re-sequencing whole genomes of several laboratory domesticated B. subtilis 168 derivatives has already been attempted using short read sequencing data, the assembly of the whole genome sequence of a closely related strain, B. subtilis natto, from very short read data is more challenging, particularly with our aim to assemble one fully connected scaffold from short reads around 35 bp in length.
  
  
  RESULTS
  We applied a comparative genome assembly method, which combines de novo assembly and reference guided assembly, to one of the B. subtilis natto strains. We successfully assembled 28 scaffolds and managed to avoid substantial fragmentation. Completion of the assembly through long PCR experiments resulted in one connected scaffold for B. subtilis natto. Based on the assembled genome sequence, our orthologous gene analysis between natto BEST195 and Marburg 168 revealed that 82.4% of 4375 predicted genes in BEST195 are one-to-one orthologous to genes in 168, with two genes in-paralog, 3.2% are deleted in 168, 14.3% are inserted in BEST195, and 5.9% of genes present in 168 are deleted in BEST195. The natto genome contains the same alleles in the promoter region of degQ and the coding region of swrAA as the wild strain, RO-FF-1. These are specific for gamma-PGA production ability, which is related to natto production. Further, the B. subtilis natto strain completely lacked a polyketide synthesis operon, disrupted the plipastatin production operon, and possesses previously unidentified transposases.
  
  
  CONCLUSIONS
  The determination of the whole genome sequence of Bacillus subtilis natto provided detailed analyses of a set of genes related to natto production, demonstrating the number and locations of insertion sequences that B. subtilis natto harbors but B. subtilis 168 lacks. Multiple genome-level comparisons among five closely related Bacillus species were also carried out. The determined genome sequence of B. subtilis natto and gene annotations are available from the Natto genome browser http://natto-genome.org/.
authors.affiliation: Department of Biosciences and Informatics, Keio University, Hiyoshi, Kohoku-ku, Yokohama, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Nishito
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Osana
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hachiya
authors.forename: Kris
authors.initials: K
authors.lastname: Popendorf
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.forename: Asao
authors.initials: A
authors.lastname: Fujiyama
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Itaya
authors.forename: Yasubumi
authors.initials: Y
authors.lastname: Sakakibara
mesh_terms: D001412:Bacillus subtilis / Q000145:classification* / Q000235:genetics*; D016680:Genome, Bacterial; D017422:Sequence Analysis, DNA / Q000379:methods*; D045730:Soy Foods / Q000382:microbiology
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