Abstract

Two Gram-positive, rod-shaped, alkalo-tolerant (pH 10.5), spore-forming bacteria (KSC-SF-8bT and KSC-SF-10a) were isolated from surfaces within the Payload Hazardous Servicing Facility (PHSF) where robotic spacecraft are assembled and tested before launch. Based on 16S rRNA gene sequence similarity, these strains were shown to belong to the family Bacillaceae and related to the genus Bacillus. The highest 16S rRNA gene sequence similarity was ~97.5% between the novel strains and the H2S producing B. selenatarsenatis. Several phenotypic characteristics such as growth at 10% NaCl, assimilation of D-melibiose and lactose were useful in the discrimination of this novel species from the closely related alkalo-tolerant (pH 10.5) species, B. firmus and B. selenatarsenatis. The results of DNA-DNA hybridization studies revealed that KSC-SF-8bT maintained less than 45% reassociation values with its closest genotypic neighbors. The combination of unique phenotypic and genotypic characteristics allowed the differentiation of these alkalo- and halo-tolerant spore-forming strains from related Bacillus species, for which the name Bacillus canaveralius sp. nov. is proposed. The type strain of this novel species is KSC-SF-8bT (=ATCC BAA-1493T =MTCC 8908T).