Comparative genomic and metabolic analysis of manganese-oxidizing mechanisms in Celeribacter manganoxidans DY25: Its adaptation to the environment of polymetallic nodules.

Manganese (Mn) nodule is one of the ubiquitous polymetallic concretions and mainly consists of Mn - Fe oxi-hydroxide precipitations. A primary oxidation of Mn(II) to MnO, in which microorganisms may play important roles, is followed by agglomeration of MnO into nodules. Celeribater manganoxidans DY25, belonging to family Rhodobacteraceae, has ability to catalyze the formation of MnO [1]. The concentration of MnO formed by harvested cells reached 7.08 μM after suspended in 10 mM HEPES (pH 7.5). Genomic and physiological characteristics of strain DY25 provided a better understanding of its Mn-oxidizing mechanism. Fifteen genes (including four multicopper oxidases) may be involved in Mn(II)-oxidation, whereas only three of them can promote this process. Sulfur-oxidizing activity was detected, which may be associated with manganese oxidation. Genes involved in import and export of primary elemental ingredients (C, N, P and S) and metallic elements (e.g. Mn) were discovered, demonstrating its potential roles in the biogeochemical cycle.