Surreal underwater scene showcasing fish swimming around a DNA strand representing the Photobacterium damselae subsp. piscicida genome, with aquaculture farms in the background.

Unlocking Aquaculture Secrets: The Genome of a Fish Killer

Beau Callahan in Science & Nature August 2025 • 4 min read.

"Decoding Photobacterium damselae subsp. piscicida to Safeguard Fish Farms Worldwide"

Aquaculture, the farming of aquatic organisms, is a vital source of food and economic stability for many regions worldwide. However, this industry faces numerous challenges, one of the most significant being disease outbreaks. Among the culprits causing havoc in fish farms, Photobacterium damselae subsp. piscicida stands out as a particularly devastating pathogen.

This bacterium is the causative agent of pasteurellosis, a severe septicemic disease that affects a wide range of fish species. From the United States to Japan and Europe, aquaculture farms have suffered significant economic losses due to outbreaks of this disease. Understanding the genetic makeup of P. damselae subsp. piscicida is crucial for developing effective strategies to combat its spread and impact.

Recent research has focused on unraveling the complete genome sequence of different strains of P. damselae subsp. piscicida, aiming to identify key differences and potential vulnerabilities. One such study details the whole-genome sequence of strain 91-197, isolated from a hybrid striped bass in the United States, providing valuable insights into the genetic characteristics of this pathogen.

Decoding the Genome of P. damselae subsp. piscicida Strain 91-197

Surreal underwater scene showcasing fish swimming around a DNA strand representing the Photobacterium damselae subsp. piscicida genome, with aquaculture farms in the background.

The study, conducted by a team of researchers from various institutions, including the University of Miyazaki and Louisiana State University, delved into the genomic structure of P. damselae subsp. piscicida strain 91-197. This particular strain was isolated from a hybrid striped bass (Morone sp.) in the United States, making it a relevant subject for understanding the pathogen's characteristics in this region.

Using advanced sequencing technologies, the researchers were able to determine the complete genome sequence of strain 91-197. The analysis revealed that the genome consists of two circular chromosomes and two plasmids, providing a comprehensive view of the bacterium's genetic architecture. The genome was found to contain:

Chromosome 1: 3,172,118 base pairs with 3,212 coding sequences.
Chromosome 2: 1,054,589 base pairs with 1,496 coding sequences.
Plasmid 1: 37,140 base pairs encoding 47 coding sequences.
Plasmid 2: 29,328 base pairs encoding 30 coding sequences.

Further comparison with other strains, such as the Japanese isolate OT-51443, revealed significant differences in genome size and gene content. These variations could potentially explain differences in virulence, host specificity, or geographic distribution. By identifying these unique genetic markers, scientists can develop targeted strategies for disease diagnosis, prevention, and treatment.

Implications for Aquaculture and Beyond

The detailed genomic information obtained from this study provides a crucial foundation for understanding the biology and pathogenicity of P. damselae subsp. piscicida. This knowledge can be leveraged to develop improved diagnostic tools, effective vaccines, and targeted antimicrobial therapies. Ultimately, this research contributes to safeguarding aquaculture farms from the devastating impacts of fish pasteurellosis and ensuring the sustainability of this vital industry.

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This article is based on research published under:

DOI-LINK: 10.1128/genomea.00600-17, Alternate LINK

Title: Whole-Genome Sequence Of Photobacterium Damselae Subsp. Piscicida Strain 91-197, Isolated From Hybrid Striped Bass ( Morone Sp.) In The United States

Subject: Genetics

Journal: Genome Announcements

Publisher: American Society for Microbiology

Authors: Yuki Teru, Jun-Ichi Hikima, Tomoya Kono, Masahiro Sakai, Tomokazu Takano, John P. Hawke, Haruko Takeyama, Takashi Aoki

Published: 2017-07-20

Everything You Need To Know

What impact does Photobacterium damselae subsp. piscicida have on aquaculture?

Photobacterium damselae subsp. piscicida causes pasteurellosis, a severe septicemic disease in various fish species. Outbreaks of this disease have led to substantial economic losses in aquaculture farms across the United States, Japan, and Europe. Understanding the genetic makeup of Photobacterium damselae subsp. piscicida is crucial for developing strategies to combat its spread and impact on aquaculture.

What are the key components of the genome in Photobacterium damselae subsp. piscicida strain 91-197?

The study of Photobacterium damselae subsp. piscicida strain 91-197 revealed that the genome consists of two circular chromosomes and two plasmids. Chromosome 1 contains 3,172,118 base pairs with 3,212 coding sequences, chromosome 2 contains 1,054,589 base pairs with 1,496 coding sequences, plasmid 1 contains 37,140 base pairs encoding 47 coding sequences, and plasmid 2 contains 29,328 base pairs encoding 30 coding sequences. This detailed genetic architecture provides insights into the bacterium's functionality and potential vulnerabilities.

How does the genome of Photobacterium damselae subsp. piscicida strain 91-197 compare to other strains?

Comparing the genome of Photobacterium damselae subsp. piscicida strain 91-197 with other strains, such as the Japanese isolate OT-51443, reveals significant differences in genome size and gene content. These variations might explain differences in virulence, host specificity, or geographic distribution. Identifying these unique genetic markers is essential for developing targeted strategies for disease diagnosis, prevention, and treatment.

What are the potential applications of the genomic information derived from Photobacterium damselae subsp. piscicida research?

The genomic information obtained from studying Photobacterium damselae subsp. piscicida contributes to developing improved diagnostic tools, effective vaccines, and targeted antimicrobial therapies. This knowledge is crucial for safeguarding aquaculture farms from the devastating impacts of fish pasteurellosis and ensuring the sustainability of the aquaculture industry. Further research can explore specific genes responsible for virulence and resistance to develop even more precise interventions.

What are the limitations of focusing on only one strain of Photobacterium damselae subsp. piscicida, and what further research is needed?

The study focused on Photobacterium damselae subsp. piscicida strain 91-197, isolated from a hybrid striped bass in the United States. While this provides valuable insights into the pathogen's characteristics in this region, further research on strains from other geographic locations and host species is needed to obtain a comprehensive understanding of the bacterium's genetic diversity and adaptation mechanisms. This broader understanding will facilitate the development of universal strategies for managing pasteurellosis in aquaculture.