Bacterial Community Composition change in Temperate Octocoral, Scleronephthya gracillimum Responding to Season and Heat Stress

Abstract

Coral diversity is affected by climate change. Environmental impacts can induce the change of relationship between coral and its symbiotic microbial community. Furthermore the microbial community change could lead the coral diseases considered one of the reasons of coral death and the opportunistic infections in corals exposed to the increased temperature. In this study we collected a temperate octocoral, Scleronephthya gracillimum in Jeju,Korea and exposed to various seawater temperature (26, 28 and 30ºC ) to compare the composition of bacterial community using the Next Generation Sequencing technique. The results showed total 88 species of bacteria were found in S.gracillimum in wild condition and they were classified to 72 genus, 41 family, 32 order, 16 class and 13 phylum. Soft coral, S.gracillimum were enriched in OTUs from the families Hahellaceae, Mycoplasmataceae, Alteromonadaceae, Anaplasmataceae, and Rhodobacteraceae. The number of bacteria species belong to following 8 families, Flavobacteriaceae, Bacillaceae, Comamonadaceae, Alteromonadaceae, Pseudoalteromonadaceae, Hahellaceae, Pseudomonadaceae and Vibrionaceae robustly increased in responses to the heat stress in 26, 28 and 30ºC groups and the species Mesoflavibacter sabulilitoris, Vibrio tubiashii, Pseudomonas azotoformans, Oceanospirillum beijerinckii, Neptuniibacter Caesariensis, and Amphritea spongicola showed proportionally increase by temperature. The number of Endozoicomonas elysicola showed an increase up to 26ºC then decrease in 28 and 30ºC groups.