Draft genome sequences and functional annotation data for two Pseudoalteromonas isolates from coastal seawater off Jeju Island, Republic of Korea
This study presents the draft genome sequences and functional annotations of two pigmented *Pseudoalteromonas* strains isolated from Jeju Island, highlighting a unique indole-type biosynthetic gene cluster responsible for purple pigmentation in strain J2K-J979.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
The ocean is not merely a vast expanse of water; it is a bustling city of microscopic life, teeming with bacteria that have evolved to survive in conditions that would challenge most other organisms. Among these residents is a genus of bacteria called Pseudoalteromonas, which thrives in marine environments and is famous for its ability to produce a wide array of chemical compounds. These bacteria act as tiny chemical factories, synthesizing substances that can break down complex materials, fight off competitors, or create vibrant colors. Scientists have long been interested in these capabilities because the compounds they produce often have potential uses in medicine, agriculture, and industry. One particularly fascinating group of these chemicals are pigments, the molecules responsible for the bright colors seen in nature, which often come with useful properties like the ability to kill harmful microbes or protect against damage.
In a recent study, researchers turned their attention to two specific strains of these marine bacteria, which they discovered in the coastal waters off Jeju Island in the Republic of Korea. The team, led by scientists from J2K Bio Co., Ltd. and Jeju National University, isolated these bacteria from the seawater and noticed something immediately striking: the two strains looked completely different when grown in a laboratory. One strain, named J2K-J031, formed colonies that were a creamy white color, while the other, J2K-J979, produced colonies of a deep, vivid purple. This visual difference suggested that the two bacteria, despite being closely related, were operating with different genetic instructions. To understand exactly why one was white and the other purple, the researchers decided to read the complete genetic code, or genome, of both strains.
The researchers began by sequencing the DNA of both bacteria using high-speed machines that read the genetic letters in short pieces, which were then pieced together like a complex puzzle to create a draft map of the entire genome. The resulting maps showed that both bacteria were quite similar in size, with genomes containing roughly 4.4 million letters of genetic code. They also shared many of the same basic functions, such as the ability to digest sugars and perform general cellular tasks. However, when the scientists looked closer at the specific sections of DNA responsible for making new chemicals, a clear difference emerged. The purple strain, J2K-J979, possessed a specific set of genes that the white strain, J2K-J031, completely lacked.
This missing set of genes in the white strain is known as the vioABCDE cluster, a group of instructions that bacteria use to build a pigment called violacein. Violacein is a deep purple substance known for its ability to fight bacteria and fungi, and it is also a powerful antioxidant. The presence of this gene cluster in the purple strain explains its color, while its absence in the white strain explains why it remains cream-colored. To confirm that these genes were indeed the source of the pigment, the researchers compared the genetic sequence of the purple strain's cluster against similar sequences found in other bacteria around the world. They found that the genes in their new strain fit neatly into a family tree of Pseudoalteromonas bacteria, closely matching those found in other marine species known to produce similar colors.
While the study successfully identified the genetic blueprint for the purple pigment, the researchers were careful to note what they had not yet done. The work provided a detailed map of the genes and a strong prediction that these genes are responsible for the color, but the team did not yet isolate the pigment itself to prove its chemical identity or test its strength in a lab setting. The findings remain a computational discovery, a high-resolution snapshot of the bacteria's potential rather than a confirmed chemical product. Nevertheless, the data offers a valuable resource for the scientific community, providing a clear genetic starting point for future studies. By making these genome sequences and annotations publicly available, the researchers have handed other scientists the tools needed to explore how these marine bacteria produce their colors and to investigate whether the purple pigment they carry holds new secrets for medicine or industry.
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