Shareen A Abdul Malik1, Santiago Cadena2, Abril Gamboa-Muñoz2, José Q. García-Maldonado2, Nathalie Bourgougnon3 and Daniel Robledo2
1Université de Rennes 1, Inserm, EHSEP, Irset (Institut de recherche en santé environnement et travail), UMR_S 1085, Rennes, France
2Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Mérida, Departamento de Recursos del Mar, Yucatán, Mexico
3Université Bretagne Sud, EA 3884, LBCM, IUEM, F-56000 Vannes, France
Complex host-microbiome interactions are fundamental for algal defence and resilience. Such interactions are prone to a paradigm shift from beneficial to detrimental when the alga is exposed to environmental stressors. We aimed at determining the bacterial community shift from healthy to disease (bleached) status to improve our current knowledge of the Florideophyceae Halymenia floresii – microbiome interactions and to explore how far the bacterial partners depend on the host health status. Thus, the structure and composition of H. floresii-associated bacterial partners were characterized through 16S rRNA gene high-throughput sequencing. Principal Coordinate Analysis, based on the weighted UniFrac distance, showed differences in the algal-associated bacterial community according to the host’s health status. The bacterial communities of healthy, faded and bleached H. floresii was composed of 8 phyla, 10 classes, 21 orders, 27 families, and 24 genera. Shannon and Simpson alpha diversity indices vary from 2.4 – 4.0 and 0.90 – 0.97, significantly differing from the host’s health status. In the healthy holobiont, the predominant phyla were Cyanobacteria (17-52%) and Proteobacteria (46-81%), Bacteroidetes (8-30%) and Proteobacteria (47-82%) being mainly observed in the faded and bleached host. Interestingly, in the healthy host, only one lineage, Novosphingobium (33-50%), was well represented, whereas their abundance was significantly reduced in the faded and bleached specimens (3-9% and 13-23%, respectively). This study firstly reports the bacterial partners of H. floresii related to healthy to bleached shift and improve our understanding of the changing microbiome on marine red algae and their potential ecological function.