A novel small antibacterial peptide was obtained from the liquid culture of Brevibacillus brevis XDH, which is a broad-spectrum antagonistic bacterium isolated from the soil of Mountain Tai, China. This peptide was purified from the fermentation medium of strain XDH via ammonium sulfate precipitation, cation exchange chromatography, and reversed-phase high-performance liquid chromatography (HPLC), successively. The structure of the active linear peptide was elucidated using mass spectra (MS) and nuclear magnetic resonance (NMR) analyses that consisted of nine amino acids. This peptide was easily soluble in water, thermally stable and strongly inhibited the growth of Escherichia coli and Staphylococcus aureus in vitro. The present data support the identification of a novel antibacterial peptide, which was named Tostadin. (C) 2012 Elsevier Ltd. All rights reserved.