A Simple Microbiome in the European Common Cuttlefish, Sepia officinalis

Area of Science:

• Microbiology
• Marine Biology
• Aquaculture

Background:

• The European common cuttlefish (Sepia officinalis) is crucial for research, but its microbiome is not well understood.
• Understanding host-microbe interactions is vital for cephalopod physiology and health, particularly in mariculture settings.

Purpose of the Study:

• To characterize the microbiome of mariculture-raised Sepia officinalis across its digestive tract, gills, and skin.
• To identify dominant bacterial symbionts and their colonization sites within the cuttlefish.

Main Methods:

• Utilized 16S rRNA amplicon sequencing to analyze bacterial composition.
• Employed quantitative PCR (qPCR) to determine bacterial abundance.
• Used fluorescence spectral imaging to visualize bacterial distribution.

Main Results:

• The cuttlefish microbiota is simplified, primarily comprising two bacterial amplicon sequence variants (ASVs) from Vibrionaceae and Piscirickettsiaceae.
• The esophagus showed dense colonization by a specific Vibrio ASV, forming a distinct layer, while other digestive organs had lower, scattered Vibrio presence.
• Gills were dominated by a Piscirickettsiaceae ASV, visualized as small cell clusters.

Conclusions:

• Gammaproteobacteria, particularly Vibrio and Piscirickettsiaceae, are major symbionts in captive-bred Sepia officinalis.
• The esophagus and gills represent significant colonization sites for these bacteria.
• Findings expand knowledge of Vibrio associations and are relevant for cephalopod health in mariculture.