Genomic characterization of Nocardia seriolae strains isolated from diseased fish

Abstract

Members of the genus Nocardia are widespread in diverse environments; a wide range of Nocardia species are known to cause nocardiosis in several animals, including cat, dog, fish, and humans. Of the pathogenic Nocardia species, N. seriolae is known to cause disease in cultured fish, resulting in major economic loss. We isolated two N. seriolae strains, CK-14008 and EM15050, from diseased fish and sequenced their genomes using the PacBio sequencing platform. To identify their genomic features, we compared their genomes with those of other Nocardia species. Phylogenetic analysis showed that N. seriolae shares a common ancestor with a putative human pathogenic Nocardia species. Moreover, N. seriolae strains were phylogenetically divided into four clusters according to host fish families. Through genome comparison, we observed that the putative pathogenic Nocardia strains had additional genes for iron acquisition. Dozens of antibiotic resistance genes were detected in the genomes of N. seriolae strains; most of the antibiotics were involved in the inhibition of the biosynthesis of proteins or cell walls. Our results demonstrated the virulence features and antibiotic resistance of fish pathogenic N. seriolae strains at the genomic level. These results may be useful to develop strategies for the prevention of fish nocardiosis.

Isolation and Characterization of Nocardiae Associated with Foaming Coastal Marine Waters

“…Accordingly, data like the one presented in this study might be of importance indicting infectious capacities of locally isolated nocardiae in human hosts. Terrigenous origin actinomycetes can adapt to marine environments with diversified functions and adaptability [ 46 ] and increasing presence of fish pathogenic nocardiae in marine and aquaculture environments reported in other parts of the world might be an indication of such adaptation [ 47 ].…”

Isolation and characterization of Nocardia seriolae , a causative agent of systematic granuloma in cultured East Asian four finger threadfin, Eleutheronema rhadinum, and red snapper, Lutjanus erythropterus

“…Antibiotic susceptibility of N. seriolae has been studied in Taiwan and Japan, where N. seriolae was found to be resistant to erythromycin and oxytetracycline (Chang et al., 2016; Han et al., 2019). Some of these N. seriolae isolates (10 from 16) were also found to be resistant to erythromycin (Imajoh et al., 2016).…”

Genomic Virulence Features of Two Novel Species Nocardia barduliensis sp. nov. and Nocardia gipuzkoensis sp. nov., Isolated from Patients with Chronic Pulmonary Diseases

“…They have also been detected in soil-living actinomycetes such as Frankia , Streptomyces and Rhodococcus [ 77 ]. However, Han et al [ 78 ] found that only the Nocardia species originated from human clinical samples ( N. concava , N. inohanensis , N. niigatensis , and N. yamanashiensis ), harbored in their genomes the gvp genes [ 78 ]. The synteny of gvp and nar clusters ( Figure 3 ) raises the question whether the nitrate reduction pathway and the gas vesicle formation are co-expressed during the infectivity process.…”