Brevibacillus brevis NBRC 100599 (= 47), which was formerly known as Bacillus brevis 47, is a strictly aerobic, gram-positive, spore-forming bacterium isolated from soil. B. brevis NBRC 100599 has a characteristic three-layered cell wall composed of a peptidoglycan-layer and the outer two S-layers, each consisting of single protein species, and is known to secrete large amounts of proteins into the culture media. The proteins secreted by this strain are mainly derived from the outer two layers of the cell wall, which are shed into the medium with the progress of cell growth. In contrast to its ability of efficient production and secretion of cell wall proteins, this bacterium secretes little protease, which enables easy recovery of the secreted proteins with minimal degradation. Taking advantage of these features, B. brevis NBRC 100599 has been used as a good host for production of heterologous proteins of both prokaryotic and eukaryotic origin.
Sequencing and annotation of the genome of B. brevis NBRC 100599 revealed a single circular chromosome (6,296,436 bp; G+C content of 47.3%) containing 5,949 predicted protein-coding genes, about 30% of which had orthologs in each of the Bacillus genomes. Significant synteny was observed only in the vicinity of the oriC region between B. brevis NBRC 100599 and the Bacillus species. The genome seemed to lack several sugar metabolism genes found in Bacillus subtilis, being in good agreement with the results in other strains showing that B. brevis is unable to utilize L-arabinose, D-mannose and D-xylose. The abundance of genes involved in response to environmental stress, such as those encoding sigma factors and chemotaxis receptors, suggests that this bacterium has a great capacity of adaptation to diverse environments.