Bacillus Rigiliprofundi sp. nov., an endospore-forming, mn-oxidizing, moderately halophilic bacterium isolated from deep subseafloor basaltic crust

A facultatively anaerobic bacterium, designated strain 1MBB1^T, was isolated from basaltic breccia collected from 341 m below the seafloor by seafloor drilling of Rigil Guyot during Integrated Ocean Drilling Program Expedition 330. The cells were straight rods, 0.5μm wide and 1–3 μm long, that occurred singly and in chains. Strain 1MBB1^T stained Gram-positive. Catalase and oxidase were produced. The isolate grew optimally at 30 °C and pH 7.5, and could grow with up to 12 % (w/v) NaCl. The DNA G+C content was 40.5 mol%. The major cellular fatty acids were C₁₆:₁ω11c (26.5 %), anteiso-C₁₅:₀ (19.5 %), C₁₆:₀ (18.7 %) and iso- C₁₅:₀ (10.4 %), and the cell-wall diamino acid was meso-diaminopimelic acid. Endospores of strain 1MBB1^T oxidized Mn(II) to Mn(IV), and siderophore production by vegetative cells was positive. Phylogenetic analysis of the 16S rRNA gene indicated that strain 1MBB1^T was a member of the family Bacillaceae, with Bacillus foraminis CV53^Tand Bacillus novalis LMG 21837^T being the closest phylogenetic neighbours (96.5 and 96.2 % similarity, respectively). This is the first novel species described from deep subseafloor basaltic crust. On the basis of our polyphasic analysis, we conclude that strain 1MBB1^T represents a novel species of the genus Bacillus, for which we propose the name Bacillus rigiliprofundi sp. nov. The type strain is 1MBB1^T (=NCMA B78^T=LMG 28275^T).