Provided are a composition containing as active ingredients thereof Bacillus subtilis strain BN1001 (deposit number: FERM P-11132) and Bacillus subtilis var. natto, a wastewater treatment system provided with a biological treatment tank that biologically treats wastewater wherein the Bacillus subtilis strain BN1001 and Bacillus subtilis var. natto are contained in the biological treatment tank, a wastewater treating method that biologically treats wastewater comprising a step for adding the Bacillus subtilis strain BN1001 and Bacillus subtilis var. natto to the wastewater, a deodorization method comprising a step for contacting the Bacillus subtilis strain BN1001 and Bacillus subtilis var. natto with a malodorous source, a support having Bacillus subtilis and Bacillus subtilis var. natto supported thereon, a wastewater treatment system wherein the support is contained in a biological treatment tank, a wastewater treating method comprising a step for adding the support to wastewater, and a batch water treating method wherein the support is contained in a biological treatment tank.
