Draft Genome Sequence of Nocardia seriolae ZJ0503, a Fish Pathogen Isolated from Trachinotus ovatus in China.

Nocardia seriolae is a pathogen that causes nocardiosis in marine and freshwater fish. Here, we report the draft genome sequence of N. seriolae strain ZJ0503, which was isolated from Trachinotus ovatus in Guangdong, China.

GENOME ANNOUNCEMENT

Nocardia seriolae is an important pathogen frequently associated with nodules and skin ulcers in fish (1). Over the last few years, N. seriolae has been an emerging pathogen that has caused increasing damage in both freshwater and marine aquaculture systems in Asia (2, 3). Until now, little was known about the pathogenic mechanism of N. seriolae. The N. seriolae strain ZJ0503, which was isolated from diseased Trachinotus ovatus in Guangdong Province, China, was chosen for sequencing. The draft genome sequence of N. seriolae strain ZJ0503 was determined using Illumina MiSeq at Novogene Bioinformatics Technology Co., Ltd. (Beijing, China). Draft assemblies were based on 1,008-Mb reads. All reads provided about 130-fold coverage of the genome. The MiSeq paired-end reads were assembled into 319 contigs in 315 scaffolds with the SOAPdenovo program. Gaps were closed by all the paired-end reads. Putative open reading frames with more than 30 amino acid residues were predicted using GeneMarkS (4). Interspersed repeat sequences (IRSs) and tandem repeat sequences (TRSs) were predicted using RepeatMasker (5). rRNAs, tRNAs, and sRNA were identified using RNAmmer (6), tRNAscan (7), and Rfam (8), respectively. The scaffolds were searched against the GO (Gene Ontology), KEGG (Kyoto Encyclopedia of Genes and Genomes), COG (Clusters of Orthologous Groups), NR (Non-Redundant Protein), Swiss-Prot, and TrEMBL databases to annotate the gene descriptions. The genome of strain ZJ0503 contains 7,708,091 nucleotides and has a G+C content of 68.25%. There are 7,426 coding sequences (CDSs) that account for 86.32% of the genome. IRSs and TRSs account for 0.055% and 0.465% of the genome, respectively. 62 tRNAs,1 rRNAs, and 105 sRNAs were predicted.

Just like other Nocardia species (9), some drug-resistant genes, such as rpoB2, FAR-1, β-lactamase, monooxygenase, FolP, and efflux pump, are also found in the genome of ZJ0503, which may explain why N. seriolae is naturally resistant to many antibiotics. CDSs for a few potential virulence-associated factors of N. seriolae, such as mammalian cell entry (mce) family protein, ATP-binding cassette (ABC) transporters, capsular polysaccharides (CPS), Myosin-cross-reactive antigen (MCRA), fibronectin-binding protein, sortase A, ESX-1, and serine protase (HtrA), were found in the genome of ZJ0503. Learning more about these factors would strengthen our understanding of the virulence of N. seriolae, and analysis of the complete genome sequence of N. seriolae strain ZJ0503 will open new avenues for the identification of novel potential vaccine targets.

Nucleotide sequence accession numbers.

This whole-genome shotgun project has been deposited at DDBJ/EMBL/GenBank the under accession number JNCT00000000. The version described in this paper is the first version and has been assigned accession number JNCT01000000.