A facultatively anaerobic, Gram-stain-positive, spore-forming Bacillus strain, 17-SMS-01T, isolated from spent mushroom substrate in the Fangshan District, Beijing, PR China, was initially identified as a Bacillus cereus group species based on 16S rRNA gene sequences. Strain 17-SMS-01T had the highest sequence similarities to Bacillus wiedmannii FSL W8-0169T (99.9 %), Bacillus albus N35-10-2T (99.9 %), Bacillus luti TD41T (99.9 %) and Bacillus proteolyticus TD42T (99.9 %). However, the average nucleotide identity (ANI) and digital DNA–DNA hybridization (DDH) values between strain 17-SMS-01T and the most closely related species were less than the previously proposed cut-off values of 96 % (ANI) and 70 % (DDH) for differentiating species within the genus, suggesting that this strain represents a novel Bacillus group species. The fatty acid profile of strain 17-SMS-01T, which showed a predominance of iso-C15 : 0 and anteiso-C15 : 0, supported the allocation of the strain to the genus Bacillus . The predominant menaquinone was MK-7 (100%). The major polar lipids were diphosphatidylglycerol, phosphatidyl ethanolamine, phosphatidyl glycerol, an unidentified aminophospholiped and unidentified lipids. The DNA G+C content of the novel strain was 35.0 mol%. The results of physiological and biochemical tests also allowed the phenotypic differentiation of strain 17-SMS-01T from the most closely related recognized species. On the basis of the phylogenetic and phenotypic evidence, strain 17-SMS-01T represents a novel Bacillus species, for which the name Bacillus fungorum sp. nov. is proposed. Type strain of the novel species is 17-SMS-01T (=MCCC 1K03483T=KCTC 33949T).