Abstract
The filamentous fungus Aspergillus kawachii has traditionally been used for brewing the Japanese distilled spirit shochu. A. kawachii characteristically hyperproduces citric acid and a variety of polysaccharide glycoside hydrolases. Here the genome sequence of A. kawachii IFO 4308 was determined and annotated. Analysis of the sequence may provide insight into the properties of this fungus that make it superior for use in shochu production, leading to the further development of A. kawachii for industrial applications.
GENOME ANNOUNCEMENT
Several species of the filamentous fungus genus Aspergillus have traditionally been used as koji molds for brewing alcoholic beverages in Japan. Koji is rice or barley that has been polished, steamed, and covered with the hyphal growth of a fungus, whose secreted enzymes convert the starch present in the grains to sugars (1). Yellow koji mold, Aspergillus oryzae, has been used for brewing sake (5), while a black koji mold, A. awamori, and its albino mutant, the white koji mold A. kawachii, have been used for making the distilled spirit shochu. Since shochu is produced mainly in the southwest Japanese island of Kyushu, where the climate is relatively warmer than that in places more well known for sake brewing, citric acid-producing A. awamori and A. kawachii were selected for making shochu to prevent undesirable contamination from bacteria. Although these two species of koji mold are phylogenetically close to A. niger, they are distinctly separated from A. niger (12).
Here we present the genome sequence of A. kawachii IFO 4308. The genomic DNA of strain IFO 4308 was sequenced to 17-fold coverage by a whole-genome shotgun strategy. One shotgun and 0.5 pair-end runs were performed using a Roche 454 GS (FLX Titanium) pyrosequencer. All of the reads were assembled using the Newbler Assembler 2.5 software program (454 Life Science), which generated 1,687 large contigs (>500 bp) and 318 scaffolds with N50 sizes of 138 and 897 kb. The genome annotation of the obtained scaffolds was performed based on the AUGUSTUS v2.5 software program (11), which was trained for predicting genes in A. fumigatus, A. nidulans, A. oryzae, and A. terreus (4, 5, 7, 9), and on BLAST searches against a nonredundant protein sequence database.
The draft genome of A. kawachii IFO 4308 includes 36,575,290 bp and is comprised of 11,488 predicted coding sequences (CDSs) with a G+C content of 49.9%. The genome contains 267 tRNAs predicted by the tRNAscan-SE 1.21 server (10).
Several A. niger strains produce ochratoxin A (OTA), whose synthesis is thought to be mediated in part by polyketide synthase (An15g07920), encoded by the pks gene (8, 9). A. niger strain CBS 513.88 carries the pks gene (9), but A. niger ATCC 1015 has lost part of the pks gene (2). A. kawachii IFO 4308 does not produce OTA (12). Accordingly, genome sequencing revealed that this fungus has lost a 21-kb region in the region of An15g07920 in a manner similar to that for A. niger ATCC 1015 (2).
A. kawachii and A. niger characteristically produce large amounts of citric acid in culture. Our genomic analysis revealed that A. kawachii possesses a complete tricarboxylic acid cycle and that the genes involved in the synthesis and degradation of citric acid are conserved with those of A. niger (2, 9).
Aspergilli produce a variety of glycoside hydrolases (GHs) (6). The genes encoding GH in A. kawachii were identified and classified based on the CAZy database (3). In the A. kawachii genome, we identified 247 GH genes that could be classified into 53 families out of a total of 125 known GH families.
Nucleotide sequence accession numbers.
The nucleotide sequence of the A. kawachii genome has been deposited in DDBJ/EMBL/GenBank under the accession numbers DF126447 to DF126592, BACL01000001 to BACL01001641, and AP012272.
Acknowledgments
We thank Akiko Enomoto and Tomoko Hidaka for technical support of 454 GS-FLX Titanium pyrosequencing.
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