Linking bacterial tetrabromopyrrole biosynthesis to coral metamorphosis

Area of Science:

• Marine microbiology
• Coral biology
• Biochemistry

Background:

• Coral fitness is influenced by associated bacteria.
• Bacterial symbionts stimulate coral larval settlement and metamorphosis.
• Tetrabromopyrrole (TBP) is a bacterial metabolite known to induce coral metamorphosis.

Purpose of the Study:

• To investigate the role of TBP biosynthesis in bacterial stimulation of coral metamorphosis.
• To confirm if live Pseudoalteromonas bacteria require TBP production to induce metamorphosis in Porites astreoides.
• To develop genetic tools for studying coral-bacterial interactions.

Main Methods:

• Generated a Pseudoalteromonas sp. PS5 mutant lacking the TBP brominase gene (bmp2).
• Assessed the ability of the mutant and wild-type bacteria to stimulate Porites astreoides metamorphosis.
• Analyzed TBP biosynthesis gene expression under different growth conditions.
• Developed a transposon plasmid for bacterial genetic manipulation and labeling.

Main Results:

• The bmp2 gene is essential for TBP biosynthesis in Pseudoalteromonas sp. PS5.
• Mutation of bmp2 abolished the bacterium's ability to stimulate coral metamorphosis.
• TBP biosynthesis gene expression was highest in stationary and biofilm growth phases.
• Established new genetic tools for studying coral-associated bacteria.

Conclusions:

• Functionally linked TBP biosynthesis in live bacteria to a coral morphogenic effect.
• Demonstrated the critical role of TBP in bacterial induction of coral metamorphosis.
• Provided novel genetic tools for future research on coral-microbe symbiosis and coral restoration efforts.