Journal of the Marine Biological Association of India

Comparative analysis of bacterial communities associated with zooxanthellate jellyfish in indoor and outdoor culture systems

Volume 67 Issue 2

S. Ancy Rosaly, L. Ranjith, Raju Saravanan, C. Kalidas, D. Linga Prabu, M. Kavitha, D. Sarathapriya, R. Vinothkumar1 and P. S. Asha

doi:10.6024/jmbai.2025.67.2.2631-07

Abstract

The upside-down jellyfish, Cassiopea sp., harbours symbiotic photosynthetic dinoflagellates (zooxanthellae) and distinct bacterial communities that contribute to its health and ecological functions. The present study was undertaken to examine the bacterial assemblages associated with Cassiopea under indoor and outdoor conditions at the Cnidarian Laboratory of the ICAR-Tuticorin Regional Station of the Central Marine Fisheries Research Institute (CMFRI). Twelve bacterial strains were isolated and identified using biochemical assays and 16S rRNA gene sequencing. The dominant families were Vibrionaceae (seven species), followed by Bacillaceae (four species) and Pseudoalteromonadaceae (one species). In outdoor systems, the dominant bacterial strains in the medusae were Photobacterium spp. (three strains) and Bacillus spp. (two species), whereas indoor systems were dominated by Vibrio spp. (three species) and Pseudoalteromonas sp. These findings on the community composition differed significantly (p<0.01) between indoor (Vibrio-dominated) and outdoor (Photobacterium-dominated) culture systems, highlighting system- specific bacterial associations in the upside-down jellyfish. This is the first documentation of system-specific bacterial associations in Cassiopea sp. from controlled culture conditions in India, underscoring the novelty of our findings and their implications for understanding host–microbe interactions and optimising jellyfish husbandry.

Keywords

Upside-down jellyfish, Cassiopea sp., 16S rRNA, Pseudoalteromonadaceae, symbiosis, vbrionaceae

Date : 27-11-2025