Bacterial diversity in the jelly of shark Ampullae of Lorenzini: a holobiont perspective

The Ampullae of Lorenzini (AoL) are specialized electrosensory organs found in sharks and other chondrichthyans. They allow the detection of electric fields, temperature changes, and salinity variations. These organs contain a jelly composed of mucopolysaccharides, proteins, and ions, whose microbiota had not been previously characterized. In this study, we investigated and described the presence of bacteria associated with the AoL jelly in seven shark species from the Mexican coast, including three species from the family Sphyrnidae and four from the family Carcharhinidae. Bacteria present in the AoL jelly were cultured on selective media and characterized through 16S rRNA gene sequencing and phylogenetic analysis. We identified bacterial species belonging to the families Staphylococcaceae, Micrococcaceae, Bacillaceae, Vibrionaceae, Aeromonadaceae, and Microbacteriaceae. Additionally, we performed whole-genome sequencing of a subset of these bacterial isolates using the Illumina platform to identify genes related to AoL colonization and potential biological functions. We propose that the bacteria found in the jelly may be regular inhabitants of the AoL, as it provides the nutrients necessary for their persistence. This study represents the first report of bacteria associated with the AoL jelly in sharks, offering new insights into the microbiota of these organs and their potential influence on electrosensory function.