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Published on: April 21, 2015
Phenotypic characteristics of Streptococcus iniae and Streptococcus parauberis isolated from olive flounder
Seong-Won Nho1, Gee-Wook Shin, Seong-Bin Park
1Laboratory of Aquatic Animal Diseases, Research Institute of Life Science, College of Veterinary medicine, Gyeongsang National University, Jinju, Gyeongnam, Korea.
Abstract:
The etiological agents of streptococcosis were isolated from diseased olive flounder collected on the Jeju island of Korea. A total of 151 bacterial isolates were collected between 2003 and 2006. The isolates were examined using various phenotypic and proteomic analyses, including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, and glycoprotein assays. In addition, isolates were grown on blood agar to assess hemolytic activity, and biochemical assays were performed using the API20 Strep kit. Our results revealed that all isolates were nonmotile, Gram-positive cocci that displayed negative catalase and oxidase activities. Multiplex PCR assays revealed that 43% and 57% of the isolates were Streptococcus iniae and Streptococcus parauberis, respectively. These results were consistent with those of the SDS-PAGE and immunoblot analyses using whole-cell lysates of bacterial isolates. Significant differences were observed with respect to the Voges-Proskauer, pyrrodonyl arylamidase, alkaline phosphatase, and hemolytic activities of the S. iniae and S. parauberis isolates. Isolates of S. iniae displayed uniform profiles in the immunoblot and glycoprotein assays; however, immunoblot assays of S. parauberis isolates (using a chicken IgY antibody raised against a homologous isolate) revealed three distinct antigenic profiles. Our findings suggest that S. parauberis and S. iniae are endemic pathogens responsible for the development of streptococcosis in olive flounder.
Insights
Streptococcus iniae and Streptococcus parauberis cause streptococcosis in olive flounder. This study identified these endemic fish pathogens using phenotypic, proteomic, and PCR analyses.
Area of Science:
- Aquatic Animal Health
- Bacteriology
- Fish Pathology
Background:
- Streptococcosis is a significant disease affecting olive flounder populations.
- Identifying the specific etiological agents is crucial for disease management.
Purpose of the Study:
- To identify and characterize the bacterial species responsible for streptococcosis in olive flounder from Jeju Island, Korea.
- To differentiate between Streptococcus iniae and Streptococcus parauberis isolates.
Main Methods:
- Phenotypic analysis including Gram staining, motility tests, and catalase/oxidase activity assays.
- Proteomic analysis using SDS-PAGE and immunoblotting.
- Molecular identification via multiplex PCR and biochemical assays (API20 Strep kit).
Main Results:
- 151 isolates were collected between 2003 and 2006.
- Multiplex PCR identified 43% Streptococcus iniae and 57% Streptococcus parauberis.
- Distinct biochemical and antigenic profiles were observed between the two species.
Conclusions:
- Streptococcus parauberis and Streptococcus iniae are endemic pathogens causing streptococcosis in olive flounder.
- The study provides a comprehensive characterization of these important fish pathogens.
- Effective disease control strategies can be developed based on accurate pathogen identification.
