Serotype distribution and antibiogram of isolated from fish in South Korea.

is the dominant etiological agent of streptococcosis, the most devastating bacterial disease in the olive flounder farming industry in South Korea. In this study, the distribution of serotypes, antimicrobial susceptibility, and presence of antimicrobial resistance genes (ARGs) in isolates obtained between 1999 and 2021 was thoroughly investigated to gain insight into the dynamics of their presence and the relationship between serotypes and antimicrobial resistance. Disk diffusion testing of 103 isolates against 10 antimicrobial agents was performed, and epidemiological cut-off values generated through normalized resistance interpretation analysis were used to classify wild-type (WT) and non-wild-type (NWT) populations.

Evaluation of MIC distribution and establishment of epidemiological cut-off values for Streptococcus parauberis isolated from aquatic animals.

Aims: Streptococcus parauberis is responsible for the development of streptococcosis in marine fish. The aim of the current study was to determine the antimicrobial susceptibility of aquatic Strep. parauberis strains, thus establishing laboratory-specific epidemiological cut-off (COWT) values to distinguish wild-type (WT) and nonwild-type (NWT) strains.

Efficacy of a recombinant M-like protein, SimA as a subunit vaccine candidate against Streptococcus parauberis infection in olive flounder, Paralichthys olivaceus.

Streptococcus parauberis, a gram-positive cocci, causes bacterial disease in farmed fish. The recent increase in S. parauberis infection in aquatic farms in South Korea has justified the importance of vaccine development for the prevention of this disease.

Protective immunity induced by ankyrin repeat-containing protein-based DNA vaccine against rock bream iridovirus (RBIV) in rock bream (Oplegnathus fasciatus).

Rock bream iridovirus (RBIV) causes severe mass mortalities in rock bream (Oplegnathus fasciatus) and remains an unsolved problem in Korea aquaculture industry. In this study, we assessed the potential of ankyrin repeat (ANK)-containing proteins to induce protective immunity in RBIV-infected rock bream. Rock bream administered with ankyrin repeat-containing protein-based DNA vaccine (200 ng/fish) exhibited significant protection against at 4 and 8 weeks post vaccination to infected with 6.

Establishment of Epidemiological Cut-Off Values and the Distribution of Resistance Genes in and Isolated from Aquatic Animals.

The emergence of antimicrobial-resistant bacteria is an enormous challenge to public health. and are opportunistic pathogens in fish. They exert tremendous adverse effects on aquaculture production, owing to their acquired antibiotic resistance.

Functional characterization and gene expression profile of perforin-2 in starry flounder (Platichthys stellatus).

The membrane attack complex/perforin (MACPF) superfamily consists of multifunctional proteins that form pores on the membrane surface of microorganisms to induce their death and have various immune-related functions. PFN2 is a perforin-like protein with an MACPF domain, and humans with deficient PFN2 levels have increased susceptibility to bacterial infection, which can lead to fatal consequences for some patients. Therefore, in this study, we confirmed the antimicrobial function of PFN2 in starry flounder (Platichthys stellatus).

Functional analysis and gene expression profiling of extracellular cathepsin Z in red sea bream, Pagrus major.

Cathepsin Z (CTSZ) is a lysosomal cysteine protease that is known to be involved in the maintenance of homeostasis and the biological mechanisms of immune cells. In this study, we have confirmed the tissue specific expression of the cathepsin Z (PmCTSZ) gene in Pagrus major, and confirmed its biological function after producing recombinant protein using Escherichia coli (E. coli).

Nocardia seriolae infection in the cultured eel Anguilla japonica in Korea.

Mass mortality occurred at an Anguilla japonica eel farm equipped with a recirculating aquaculture system in Gimcheon, Korea, from late spring to early summer 2015. The cumulative 3-month mortality was 16% (approximately 24,300-150,000 fish). The majority of affected fish displayed ulcerative lesions that progressed to petechial haemorrhages and small white granulomas in the major organs.

Detection of genetic variation using dual-labeled peptide nucleic acid (PNA) probe-based melting point analysis.

Background: Thermal denaturation of probe-target hybrid is highly reproducible, and which makes probe melting point analysis reliable in the detection of mutations, polymorphisms and epigenetic differences in DNA. To improve resolution of these detections, we used dual-labeled (quencher and fluorescence), full base of peptide nucleic acid (PNA) probe for fluorescence probe based melting point analysis. Because of their uncharged nature and peptide bond-linked backbone, PNA probes have more favorable hybridization properties, which make a large difference in the melting temperature between specific hybridization and partial hybridization.

Draft Genome Sequence of Beta-Hemolytic Streptococcus iniae KCTC 11634.

Streptococcus iniae is a beta-hemolytic, Gram-positive coccus, which affects a broad range of freshwater and marine fish species, causing substantial economic losses in the aquaculture industry worldwide. Thus, it is very important to derive a complete genome sequence of the bacterium to aid in the development of vaccines and methods for preventing fish streptococcosis and zoonotic infections in humans. Here, we present the draft genome sequence of S.

Induction of antifouling diterpene production by Streptomyces cinnabarinus PK209 in co-culture with marine-derived Alteromonas sp. KNS-16.

An active antifouling diterpene was isolated from marine actinomycete strain PK209 and productivity was induced in a co-culture experiment. The active constituent was identified as the diterpene lobocompactol by interpretion of nuclear magnetic resonance and mass spectroscopy data. A PK209 co-culture was designed and a lobocompactol-resistant bacterium, KNS-16, was selected as co-culture competitor to induce lobocompactol production.

Isolation and structural determination of the antifouling diketopiperazines from marine-derived Streptomyces praecox 291-11.

Marine derived actinomycetes constituting 185 strains were screened for their antifouling activity against the marine seaweed, Ulva pertusa, and fouling diatom, Navicula annexa. Strain 291-11 isolated from the seaweed, Undaria pinnatifida, rhizosphere showed the highest antifouling activity and was identified as Streptomyces praecox based on a 16S rDNA sequence analysis. Strain 291-11 was therefore named S.

Mutations in the gyrB, parC, and parE genes of quinolone-resistant isolates and mutants of Edwardsiella tarda.

The full length genes gyrB (2,415 bp), parC (2,277 bp), and parE (1,896 bp) in Edwardsiella tarda were cloned by PCR with degenerate primers based on the sequence of the respective quinolone resistance-determining region (QRDR), followed by elongation of 5' and 3' ends using cassette ligation-mediated PCR (CLMP). Analysis of the cloned genes revealed open reading frames (ORFs) encoding proteins of 804 (GyrB), 758 (ParC), and 631 (ParE) amino acids with conserved gyrase/topoisomerase features and motifs important for enzymatic function. The ORFs were preceded by putative promoters, ribosome binding sites, and inverted repeats with the potential to form cruciform structures for binding of DNA-binding proteins.