Draft Genome Sequence of Aeromonas molluscorum Strain 848TT, Isolated from Bivalve Molluscs.

We report here the draft genome sequence of Aeromonas molluscorum 848T, the type strain of this Aeromonas species, which was isolated from wedge shells (Donax trunculus) obtained from a retail market in Barcelona, Spain, in 1997.

GENOME ANNOUNCEMENT

The genus Aeromonas Stanier 1943, 213AL, comprises a collection of Gram-negative, rod-shaped, non-spore-forming, oxidase- and catalase-positive, glucose-fermenting, facultatively anaerobic bacteria that are resistant to vibriostatic agent O/129 and generally motile by means of polar flagella (1). The genus Aeromonas belongs to the family Aeromonadaceae within the Gammaproteobacteria. Aeromonads are autochthonous to aquatic environments worldwide and are usual microbiota (as well as primary or secondary pathogens) of fish, amphibians, and other animals. Some motile species (mainly Aeromonas caviae, Aeromonas hydrophila, and Aeromonas veronii bv. Sobria) are opportunistic pathogens of humans (2). Aeromonas molluscorum was defined on the basis of a group of five strains that were isolated from bivalve molluscs obtained from retail markets in Barcelona in 1997 (3), which clustered together as a separate phenon in a phenotypic study (4). The type strain of this new Aeromonas species is A. molluscorum 848T (CECT 5864T, LMG 22214T). Recently, in 2010, a new strain of A. molluscorum was isolated from a tributyltin (TBT)-contaminated sediment in Ria de Aveiro, Portugal (5).

The draft genome sequence of the A. molluscorum type strain was obtained with a shotgun strategy using Roche 454 sequencing technology. A total of 122,746 reads with an average length of 404 nucleotides (9× coverage) were de novo assembled using a combined strategy (Newbler de novo and Velvet de novo). A total of 309 contigs, 304 of >1 kb in length, were constructed, with an N50 of 21,565 bp; the largest contig assembled measured 138,647 bp and the calculated genome size was 4.24 Mb, which is slightly smaller than the other Aeromonas genomes reported to date (ranging from 4.3 to 4.97 Mb) (6–14). The G+C mole percentage was 59.2.

The gene prediction and protein annotation were performed by applying the NCBI Prokaryotic Genomes Automatic Annotation Pipeline (http://www.ncbi.nlm.nih.gov/genomes/static/Pipeline.html) on the contigs assembled. A total of 3,946 protein-coding sequences were identified, together with 70 tRNA genes and 3 rRNA genes. Protein annotation using the VFDB database (http://www.mgc.ac.cn/VFs/) of virulence factors for bacterial pathogens detected six putative virulence factors, including a gene involved in ferric uptake (hemE), a gene encoding a phosphoheptose isomerase associated with lipopolysaccharide (LPS) biosynthesis (gmhA), two genes (cheW and cheY) involved in signal transmission to the flagellar motor switch component, and a regulator gene responsible for epithelial cell invasion (csrA). We detected a 36.4-kb putative prophage showing high identity to phiO18P, a bacteriophage isolated from A. media (15) and also detected in the genome sequence of A. caviae Ae398 (8). In addition to the complete sequence of phiO18P, 3 partial bacteriophage sequences were also detected. Two copies of an insertion sequence (IS) with high homology to ISAsa4 (88% identity) were discovered using the server ISFinder (http://www-is.biotoul.fr//). This IS element was previously reported in atypical strains of A. salmonicida subsp. salmonicida (16).

Nucleotide sequence accession numbers.

This Whole-Genome Shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession number AQGQ00000000 (BioProject PRJNA183610). The version described in this paper is the first version, AQGQ01000000.