RESUMEN
Pigmented bacterial symbionts play major roles in the health of coral holobionts. However, there is scarce knowledge on the diversity of these microbes for several coral species. To gain further insights into holobiont health, pigmented bacterial isolates of Fabibacter pacificus (Bacteroidetes; n = 4), Paracoccus marcusii (Alphaproteobacteria; n = 1), and Pseudoalteromonas shioyasakiensis (Gammaproteobacteria; n = 1) were obtained from the corals Mussismilia braziliensis and Montastraea cavernosa in Abrolhos Bank, Brazil. Cultures of these bacterial symbionts produced strong antioxidant activity (catalase, peroxidase, and oxidase). To explore these bacterial isolates further, we identified their major pigments by HPLC and mass spectrometry. The six phylogenetically diverse symbionts had similar pigment patterns and produced myxol and keto-carotene. In addition, similar carotenoid gene clusters were confirmed in the whole genome sequences of these symbionts, which reinforce their antioxidant potential. This study highlights the possible roles of bacterial symbionts in Montastraea and Mussismilia holobionts.
Asunto(s)
Antozoos/microbiología , Antioxidantes/metabolismo , Bacteroidetes/metabolismo , Paracoccus/metabolismo , Pigmentos Biológicos/metabolismo , Pseudoalteromonas/metabolismo , Animales , Bacteroidetes/genética , Bacteroidetes/aislamiento & purificación , Brasil , Carotenoides/metabolismo , Catalasa/biosíntesis , ADN Bacteriano/genética , Genoma Bacteriano/genética , Oxidorreductasas/biosíntesis , Paracoccus/genética , Paracoccus/aislamiento & purificación , Peroxidasa/biosíntesis , Pigmentos Biológicos/genética , Pseudoalteromonas/genética , Pseudoalteromonas/aislamiento & purificación , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , SimbiosisRESUMEN
One of the main goals of coral microbiology is to understand the ways in which coral-bacteria associations are established and maintained. This work describes the sequencing of the genome of Paracoccus sp. SM22M-07 isolated from the mucus of the endemic Brazilian coral species Mussismilia hispida. Comparative analysis was used to identify unique genomic features of SM22M-07 that might be involved in its adaptation to the marine ecosystem and the nutrient-rich environment provided by coral mucus, as well as in the establishment and strengthening of the interaction with the host. These features included genes related to the type IV protein secretion system, erythritol catabolism, and succinoglycan biosynthesis. We experimentally confirmed the production of succinoglycan by Paracoccus sp. SM22M-07 and we hypothesize that it may be involved in the association of the bacterium with coral surfaces.