Microbial Diversity and Screening for Potential Pathogens and Beneficial Bacteria of Five Jellyfish Species-Associated Microorganisms Based on 16S rRNA Sequencing

Jellyfish, microorganisms, and the marine environment collectively shape a complex ecosystem. This study aimed to analyze the microbial communities associated with five jellyfish species, exploring their composition, diversity, and relationships. Microbial diversity among the species was assessed using 16S rRNA gene sequencing and QIIME analysis. Significant differences in bacterial composition were found, with distinct dominant taxa in each species: <i>Mycoplasmataceae</i> (99.21%) in <i>Aurelia coerulea</i>, <i>Sphingomonadaceae</i> (22.81%) in <i>Cassiopea andromeda</i>, <i>Alphaproteobacteria</i>_unclassified (family level) (64.09%) in <i>Chrysaora quinquecirrha</i>, <i>Parcubacteria</i>_unclassified (family level) (93.11%) in <i>Phacellophora camtschatica</i>, and <i>Chlamydiaceae</i> (35.05%) and <i>Alphaproteobacteria</i>_unclassified (family level) (38.73%) in <i>Rhopilema esculentum</i>. <i>C. andromeda</i> showed the highest diversity, while <i>A. coerulea</i> exhibited the lowest. Correlations among dominant genera varied, including a positive correlation between <i>Parcubacteria</i>_unclassified (genus level) and <i>Chlamydiaceae_</i>unclassified (genus level). Genes were enriched in metabolic pathways and ABC transporters. The most abundant potential pathogens at the phylum level were Proteobacteria, Tenericutes, Chlamydiae, and Epsilonbacteraeota. The differing microbial compositions are likely influenced by species and their habitats. Interactions between jellyfish and microorganisms, as well as among microorganisms, showed interdependency or antagonism. Most microbial gene functions focused on metabolic pathways, warranting further study on the relationship between pathogenic bacteria and these pathways.