A Gram-positive, facultative anaerobic, motile, endospore-forming rod strain, designated DX-4(T), was isolated from an electrochemically active biofilm. Growth occurred at 30-65 A degrees C (optimum 55 A degrees C), at pH 6.0-8.5 (optimum pH 7.0-7.5) and with < 6 % (w/v) NaCl. Cells were catalase- and oxidase-positive. The main respiratory quinone was MK-7, the predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside, and unidentified aminophospholipid, the DNA G+C content was 38.6 mol% and the major fatty acids (> 5 %) were iso-C-15:0 (38.9 %), iso-C-17:0 (30.5 %), iso-C-16:0 (5.6 %), and anteiso-C-17:0 (5.2 %). The phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain DX-4(T) is a member of the genus Bacillus. The results of phenotypic, chemotaxonomic, and genotypic analyses clearly indicated that strain DX-4(T) represents a novel species, for which the name Bacillus borbori sp. nov. is proposed. The type strain is DX-4(T) (= CCTCC AB2012196(T) = KCTC 33103(T)).