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.

色素细菌共生体在珊瑚整体生物的健康中起主要作用。但是，对于几种珊瑚种类的这些微生物的多样性缺乏了解。为了获得进一步的见解holobiont健康，着色细菌分离Fabibacter pacificus（拟杆菌; ñ  = 4），副球菌marcusii（α-变形菌; ñ  = 1），和假交替单胞shioyasakiensis（γ-变形菌; ñ  = 1），从珊瑚获得Mussismilia braziliensis和Montastraea Cavernosa在巴西的Abrolhos银行。这些细菌共生菌的培养物产生强的抗氧化活性（过氧化氢酶，过氧化物酶和氧化酶）。为了进一步探索这些细菌分离株，我们通过HPLC和质谱鉴定了它们的主要色素。六个系统发育上不同的共生体具有相似的色素图案，并产生了粘胶和酮-胡萝卜素。另外，在这些共生体的全基因组序列中证实了相似的类胡萝卜素基因簇，这增强了它们的抗氧化能力。这项研究强调了细菌共生体在Montastraea和Mussismilia holobionts中的可能作用。